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strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the hubble constant, h0. we present a blind lens model analysis of the quadruply imaged quasar lens he 0435-1223 using deep hubble space telescope imaging, updated time-delay measurements from the cosmological monitoring of gravitational lenses (cosmograil), a measurement of the velocity dispersion of the lens galaxy based on keck data, and a characterization of the mass distribution along the line of sight. he 0435-1223 is the third lens analysed as a part of the h0 lenses in cosmograil's wellspring (h0licow) project. we account for various sources of systematic uncertainty, including the detailed treatment of nearby perturbers, the parametrization of the galaxy light and mass profile, and the regions used for lens modelling. we constrain the effective time-delay distance to be d_{δ t}= 2612_{-191}^{+208} mpc, a precision of 7.6 per cent. from he 0435-1223 alone, we infer a hubble constant of h0 = 73.1_{-6.0}^{+5.7} km s^{-1 mpc^{-1}} assuming a flat λcdm cosmology. the cosmographic inference based on the three lenses analysed by h0licow to date is presented in a companion paper (h0licow paper v). | h0licow - iv. lens mass model of he 0435-1223 and blind measurement of its time-delay distance for cosmology |
we present a new investigation of the thermal history of the intergalactic medium (igm) during and after reionization using the lyα forest flux power spectrum at 4.0 ≲ z ≲ 5.2. using a sample of 15 high-resolution spectra, we measure the flux power down to the smallest scales ever probed at these redshifts (-1 ≲ log(k/km-1 s) ≲ -0.7). these scales are highly sensitive to both the instantaneous temperature of the igm and the total energy injected per unit mass during and after reionization. we measure temperatures at the mean density of t 0 ∼ 7000-8000 k, consistent with no significant temperature evolution for redshifts 4.2 ≲ z ≲ 5.0. we also present the first observational constraints on the integrated igm thermal history, finding that the total energy input per unit mass increases from u 0 ∼ 4.6 to 7.3 ev {m}{{p}}-1 from z ∼ 6 to 4.2 assuming a λcdm cosmology. we show how these results can be used simultaneously to obtain information on the timing and the sources of the reionization process. our first proof of concept using simplistic models of instantaneous reionization produces results comparable to and consistent with the recent planck constraints, favoring models with {z}rei}∼ {8.5}-0.8+1.1. | revealing reionization with the thermal history of the intergalactic medium: new constraints from the lyα flux power spectrum |
aims: integral field spectroscopy (ifs) with jwst nirspec will significantly improve our understanding of the first quasars, by providing spatially resolved, infrared spectroscopic capabilities that cover key rest-frame optical emission lines that have been previously unobservable.methods: here we present our results from the first two z > 6 quasars observed as a part of the galaxy assembly with nirspec ifs (ga-nifs) gto programme, with dels j0411-0907 at z = 6.82 and vdes j0020-3653 at z = 6.86.results: by observing the hβ, [o iii] λλ4959, 5007, and hα emission lines in these high-z quasars for the first time, we measured accurate black hole masses, mbh = 1.85−0.8+2 × 109 m⊙ and 2.9−1.3+3.5 × 109m⊙, corresponding to eddington ratios of λedd = 0.8−0.4+0.7 and 0.4−0.2+0.3 for dels j0411-0907 and vdes j0020-3653, respectively. these provide a key comparison for existing estimates from the more uncertain mg ii line. we performed quasar-host decomposition using models of the quasars' broad lines to measure the underlying host galaxies. we also discovered multiple emission line regions surrounding each of the host galaxies, which are likely companion galaxies undergoing mergers with these hosts. we measured the star formation rates, excitation mechanisms, and dynamical masses of the hosts and companions, measuring the mbh/mdyn ratios at high z using these estimators for the first time. dels j0411-0907 and vdes j0020-3653 both lie above the local black hole-host mass relation, and are consistent with the existing observations of z ≳ 6 quasar host galaxies with alma. we detected ionised outflows in [o iii] λλ4959, 5007 and hβ from both quasars, with mass outflow rates of 58−37+44 and 525−92+75 m⊙ yr−1 for dels j0411-0907 and vdes j0020-3653, much larger than their host star formation rates of < 33 and < 54 m⊙ yr−1, respectively.conclusions: this work highlights the exceptional capabilities of the jwst nirspec ifu for observing quasars in the early universe. | ga-nifs: black hole and host galaxy properties of two z ≃ 6.8 quasars from the nirspec ifu |
we present a void clustering analysis in configuration-space using the completed sloan digital sky survey iv (sdss-iv) extended baryon oscillation spectroscopic survey (eboss) dr16 samples. these samples consist of luminous red galaxies (lrgs) combined with the high-redshift tail of the sdss-iii baryon oscillation spectroscopic survey (boss) dr12 cmass galaxies (called as lrg+cmass sample), emission line galaxies (elgs), and quasars (qsos). we build void catalogues from the three eboss dr16 samples using a zobov-based algorithm, providing 2814 voids, 1801 voids, and 4347 voids in the lrg+cmass, elg, and qso samples, respectively, spanning the redshift range 0.6 < z < 2.2. we measure the redshift space distortions around voids using the anisotropic void-galaxy cross-correlation function and we extract the distortion parameter β. we test the methodology on realistic simulations before applying it to the data, and we investigate all our systematic errors on these mocks. we find βlrg(z = 0.74) = 0.415 ± 0.087, βelg(z = 0.85) = 0.665 ± 0.125 and βqso(z = 1.48) = 0.313 ± 0.134, for the lrg+cmass, elg, and qso sample, respectively. the quoted errors include systematic and statistical contributions. in order to convert our measurements in terms of the growth rate fσ8, we use consensus values of linear bias from the eboss dr16 companion papers, resulting in the following constraints: fσ8(z = 0.74) = 0.50 ± 0.11, fσ8(z = 0.85) = 0.52 ± 0.10, and fσ8(z = 1.48) = 0.30 ± 0.13. our measurements are consistent with other measurements from eboss dr16 using conventional clustering techniques. | the completed sdss-iv extended baryon oscillation spectroscopic survey: growth rate of structure measurement from cosmic voids |
aims: outflows driven by active galactic nuclei (agn) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. we here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2.methods: we analysed a sample of six luminous (l > 1047 erg/s) quasars at z ~ 2.4, observed in h-band using the near-ir integral field spectrometer sinfoni at the vlt. we performed a kinematic analysis of the [oiii] emission line at λ = 5007 å.results: we detect fast, spatially extended outflows in five out of six targets. [oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. the properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the agn luminosity. the increase in outflow rate with increasing agn luminosity is consistent with the idea that a luminous agn pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity.conclusions: we derive mass outflow rates of about 6-700 m⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. the physical properties of ionised outflows show dependences on agn luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. based on observations collected at the european organisation for astronomical research in the southern hemisphere, chile, p.id: 086.b-0579(a). | ionised outflows in z ~ 2.4 quasar host galaxies |
we present chemical abundance ratios of 70 star-forming galaxies at z ~ 4-10 observed by the jwst/nirspec early release observations, glass, and ceers programs. among the 70 galaxies, we have pinpointed two galaxies, ceers_01019 at z = 8.68 and glass_150008 at z = 6.23, with extremely low c/n ([c/n] ≲ -1), evidenced with c iii]λλ1907,1909, n iii]λ1750, and n iv]λλ1483,1486, which show high n/o ratios ([n/o] ≳ 0.5) comparable with the one of gn-z11, regardless of whether stellar or active galactic nucleus radiation is assumed. such low c/n and high n/o ratios found in ceers_01019 and glass_150008 (additionally identified in gn-z11) are largely biased toward the equilibrium of the cno cycle, suggesting that these three galaxies are enriched by metals processed by the cno cycle. on the c/n versus o/h plane, these three galaxies do not coincide with galactic h ii regions, normal star-forming galaxies, and nitrogen-loud quasars with asymptotic giant branch stars, but with globular-cluster (gc) stars, indicating a connection with gc formation. we compare the c/o and n/o of these three galaxies with those of theoretical models and find that these three galaxies are explained by scenarios with dominant cno-cycle materials, i.e., wolf-rayet stars, supermassive (103-105 m ⊙) stars, and tidal disruption events, interestingly with a requirement of frequent direct collapses. for all the 70 galaxies, we present measurements of ne/o, s/o, and ar/o, together with c/o and n/o. we identify four galaxies with very low ne/o, log(ne/o) < -1.0, indicating abundant massive (≳30 m ⊙) stars. | jwst identification of extremely low c/n galaxies with [n/o] ≳ 0.5 at z 6-10 evidencing the early cno-cycle enrichment and a connection with globular cluster formation |
we present the clustering measurements of quasars in configuration space based on the data release 14 (dr14) of the sloan digital sky survey iv extended baryon oscillation spectroscopic survey (eboss). this data set includes 148 659 quasars spread over the redshift range 0.8 ≤ z ≤ 2.2 and spanning 2112.9 deg2. we use the convolution lagrangian perturbation theory approach with a gaussian streaming model for the redshift space distortions of the correlation function and demonstrate its applicability for dark matter haloes hosting eboss quasar tracers. at the effective redshift zeff = 1.52, we measure the linear growth rate of structure fσ8(zeff) = 0.426 ± 0.077, the expansion rate h(z_eff)= 159^{+12}_{-13}(rs^fid/r_s) {{}km s}^{-1} mpc^{-1}, and the angular diameter distance da(z_eff)=1850^{+90}_{-115} (r_s/rs^fid) {}mpc, where rs is the sound horizon at the end of the baryon drag epoch and rs^fid is its value in the fiducial cosmology. the quoted uncertainties include both systematic and statistical contributions. the results on the evolution of distances are consistent with the predictions of flat λ-cold dark matter cosmology with planck parameters, and the measurement of fσ8 extends the validity of general relativity to higher redshifts (z > 1). this paper is released with companion papers using the same sample. the results on the cosmological parameters of the studies are found to be in very good agreement, providing clear evidence of the complementarity and of the robustness of the first full-shape clustering measurements with the eboss dr14 quasar sample. | the clustering of the sdss-iv extended baryon oscillation spectroscopic survey dr14 quasar sample: measurement of the growth rate of structure from the anisotropic correlation function between redshift 0.8 and 2.2 |
massive disk galaxies like the milky way are expected to form at late times in traditional models of galaxy formation1,2, but recent numerical simulations suggest that such galaxies could form as early as a billion years after the big bang through the accretion of cold material and mergers3,4. observationally, it has been difficult to identify disk galaxies in emission at high redshift5,6 in order to discern between competing models of galaxy formation. here we report imaging, with a resolution of about 1.3 kiloparsecs, of the 158-micrometre emission line from singly ionized carbon, the far-infrared dust continuum and the near-ultraviolet continuum emission from a galaxy at a redshift of 4.2603, identified by detecting its absorption of quasar light. these observations show that the emission arises from gas inside a cold, dusty, rotating disk with a rotational velocity of about 272 kilometres per second. the detection of emission from carbon monoxide in the galaxy yields a molecular mass that is consistent with the estimate from the ionized carbon emission of about 72 billion solar masses. the existence of such a massive, rotationally supported, cold disk galaxy when the universe was only 1.5 billion years old favours formation through either cold-mode accretion or mergers, although its large rotational velocity and large content of cold gas remain challenging to reproduce with most numerical simulations7,8. | a cold, massive, rotating disk galaxy 1.5 billion years after the big bang |
we reinvestigate a claimed sample of 22 x-ray detected active galactic nuclei (agn) at redshifts z > 4, which has reignited the debate as to whether young galaxies or agn reionized the universe. these sources lie within the great observatories origins deep survey-south (goods-s)/cosmic assembly near-infrared deep extragalactic legacy survey (candels) field, and we examine both the robustness of the claimed x-ray detections (within the chandra 4ms imaging) and perform an independent analysis of the photometric redshifts of the optical/infrared counterparts. we confirm the reality of only 15 of the 22 reported x-ray detections, and moreover find that only 12 of the 22 optical/infrared counterpart galaxies actually lie robustly at z > 4. combining these results we find convincing evidence for only seven x-ray agn at z > 4 in the goods-s field, of which only one lies at z > 5. we recalculate the evolving far-ultraviolet (1500 å) luminosity density produced by agn at high redshift, and find that it declines rapidly from z ≃ 4 to z ≃ 6, in agreement with several other recent studies of the evolving agn luminosity function. the associated rapid decline in inferred hydrogen ionizing emissivity contributed by agn falls an order-of-magnitude short of the level required to maintain hydrogen ionization at z ≃ 6. we conclude that all available evidence continues to favour a scenario in which young galaxies reionized the universe, with agn making, at most, a very minor contribution to cosmic hydrogen reionization. | no evidence for a significant agn contribution to cosmic hydrogen reionization |
jwst is discovering star-forming 'candidate' galaxies with photometric redshifts z > 9 and little attenuation. we model presumptive massive black holes (mbhs) in such galaxies and find that their unobscured emission is fainter than the galaxy starlight in jwst filters, and difficult to be detected via colour-colour selection, and x-ray and radio observations. only mbhs overmassive relative to expected galaxy scaling relations, accreting at high eddington rates, would be detectable. their discovery would point to the presence of heavy mbh seeds, but care is needed to exclude the existence of lighter seeds as only overmassive mbhs are detectable in this type of galaxies. conversely, if no overmassive mbhs are hosted in these galaxies, either there are no heavy seeds or they are rare. the most massive/highest redshift candidate galaxies can attain stellar masses in excess of $5\times 10^{10}\, {\rm m_\odot }$ by z ~ 6 if they grow along the star formation rate-mass sequence, and can nurse an mbh growing from ${\sim}10^5 \, {\rm m_\odot }$ up to ${\gt}3\times 10^7\, {\rm m_\odot }$ by z ~ 6, to become hosts of some z > 6 quasars. candidate galaxies of $\log (m_{\rm gal}/\, {\rm m_\odot })\sim 8$ cannot grow their putative seeds fast, unless seeds are ${\gtrsim}10^6\, {\rm m_\odot }$. the number density of the jwst candidate galaxies far outnumbers that of the highest z quasar hosts and this allows for about only one bright z ~ 6-7 quasar every 1000 of these galaxies. | what if young z > 9 jwst galaxies hosted massive black holes? |
we introduce the abacushod model and present two applications of abacushod and the abacussummit simulations to observations. abacushod is a halo occupation distribution (hod) framework written in python that is particle-based, multitracer, highly generalized, and highly efficient. it is designed specifically with multitracer/cosmology analyses for next-generation large-scale structure surveys in mind, and takes advantage of the volume and precision offered by the new state-of-the-art abacussummit cosmological simulations. the model is also highly customizable and should be broadly applicable to any upcoming surveys and a diverse range of cosmological analyses. in this paper, we demonstrate the capabilities of the abacushod framework through two example applications. the first example demonstrates the high efficiency and the large hod extension feature set through an analysis of full-shape redshift-space clustering of boss galaxies at intermediate to small scales ($\lt 30\, h^{-1}$ mpc), assessing the necessity of introducing secondary galaxy biases (assembly bias). we find strong evidence for using halo environment instead of concentration to trace secondary galaxy bias, a result which also leads to a moderate reduction in the 'lensing is low' tension. the second example demonstrates the multitracer capabilities of the abacushod package through an analysis of the extended baryon oscillation spectroscopic survey cross-correlation measurements between three different galaxy tracers: luminous red galaxies, emission-line galaxies, and quasi-stellar objects. we expect the abacushod framework, in combination with the abacussummit simulation suite, to play an important role in a simulation-based analysis of the upcoming dark energy spectroscopic instrument data sets. | abacushod: a highly efficient extended multitracer hod framework and its application to boss and eboss data |
we present deep near-infrared spectroscopy of six quasars at 6.1 ≤ z ≤ 6.7 with very large telescope/x-shooter and gemini-n/gnirs. our objects, originally discovered through a wide-field optical survey with the hyper suprime-cam (hsc) subaru strategic program (hsc-ssp), have the lowest luminosities (-25.5 mag ≤ m 1450 ≤ -23.1 mag) of the z > 5.8 quasars with measured black hole (bh) masses. from single-epoch mass measurements based on mg ii λ2798, we find a wide range in bh masses, from m bh = 107.6 to 109.3 m ⊙. the eddington ratios l bol/l edd range from 0.16 to 1.1, but the majority of the hsc quasars are powered by m bh ∼ 109 m ⊙ supermassive black holes (smbhs) accreting at sub-eddington rates. the eddington ratio distribution of the hsc quasars is inclined to lower accretion rates than those of willott et al., who measured the bh masses for similarly faint z ∼ 6 quasars. this suggests that the global eddington ratio distribution is wider than has previously been thought. the presence of m bh ∼ 109 m ⊙ smbhs at z ∼ 6 cannot be explained with constant sub-eddington accretion from stellar remnant seed bhs. therefore, we may be witnessing the first buildup of the most massive bhs in the first billion years of the universe, the accretion activity of which is transforming from active growth to a quiescent phase. measurements of a larger complete sample of z ≳ 6 low-luminosity quasars, as well as deeper observations with future facilities, will enable us to better understand the early smbh growth in the reionization epoch. | subaru high-z exploration of low-luminosity quasars (shellqs). vi. black hole mass measurements of six quasars at 6.1 ≤ z ≤ 6.7 |
we present a new investigation of the intergalactic medium near reionization using dark gaps in the lyβ forest. with its lower optical depth, lyβ offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used lyα line. we identify dark gaps in the lyβ forest using spectra of 42 qsos at z em > 5.5, including new data from the xqr-30 vlt large programme. approximately 40% of these qso spectra exhibit dark gaps longer than 10 h -1 mpc at z ≃ 5.8. by comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the lyα forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at z < 6 due to a late end to reionization. of particular interest is a very long (l = 28 h -1 mpc) and dark (τ eff ≳ 6) gap persisting down to z ≃ 5.5 in the lyβ forest of the z = 5.85 qso pso j025-11. this gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of <x h i> ≳ 5% by z = 5.6. finally, we infer constraints on <x h i> over 5.5 ≲ z ≲ 6.0 based on the observed lyβ dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. we find <x h i> ≤ 0.05, 0.17, and 0.29 at z ≃ 5.55, 5.75, and 5.95, respectively. these constraints are consistent with models where reionization ends significantly later than z = 6. | long dark gaps in the lyβ forest at z < 6: evidence of ultra-late reionization from xqr-30 spectra |
we have completed two years of photometric and spectroscopic monitoring of a large number of active galactic nuclei (agns) with very high accretion rates. in this paper, we report on the result of the second phase of the campaign, during 2013-2014, and the measurements of five new hβ time lags out of eight monitored agns. all five objects were identified as super-eddington accreting massive black holes (seambhs). the highest measured accretion rates for the objects in this campaign are \mathscr{\dot{m}} {\mkern 1mu} ≳ 200, where \mathscr{\dot{m}} {\mkern 1mu} ={{\dot{m}}\bullet }/{{l}edd}{{c}-2}, {{\dot{m}}\bullet } is the mass accretion rates, {{l}edd} is the eddington luminosity and c is the speed of light. we find that the hβ time lags in seambhs are significantly shorter than those measured in sub-eddington agns, and the deviations increase with increasing accretion rates. thus, the relationship between broad-line region size ({{r}_{hβ }}) and optical luminosity at 5100 å, {{r}_{hβ }}-{{l}5100}, requires accretion rate as an additional parameter. we propose that much of the effect may be due to the strong anisotropy of the emitted slim-disk radiation. scaling {{r}_{hβ }} by the gravitational radius of the black hole (bh), we define a new radius-mass parameter (y) and show that it saturates at a critical accretion rate of \mathscr{\dot{m}} {\mkern 1mu} {{}c}=6∼ 30, indicating a transition from thin to slim accretion disk and a saturated luminosity of the slim disks. the parameter y is a very useful probe for understanding the various types of accretion onto massive bhs. we briefly comment on implications to the general population of super-eddington agns in the universe and applications to cosmology. | supermassive black holes with high accretion rates in active galactic nuclei. iv. hβ time lags and implications for super-eddington accretion |
motivated by the discovery of rare enormous lyman α nebulae (elan) around z ∼ 2 quasars, we initiated a long-term campaign with the muse/vlt instrument to directly uncover the astrophysics of the gas around quasars. we present here the first 61 targets under the acronym qso museum. these quasars are characterized by a median redshift z = 3.17, absolute i magnitude in the range -29.67 ≤ mi(z = 2) ≤ -27.03, and different levels of radio-loudness. this sample unveils diverse specimens of ly α nebulosities extending for tens of kpc around these quasars (average maximum projected distance of 80 kpc) above a surface brightness sb > 8.8 × 10-19 erg s-1 cm-2 arcsec-2(2σ). the bulk of the ly α emission is within r < 50 kpc, and is characterized by relatively quiescent kinematics, with average velocity dispersions <σly α> < 400 km s-1. therefore, the motions within all these ly α nebulosities have amplitudes consistent with gravitational motions expected in dark matter haloes hosting quasars at these redshifts, possibly reflecting the complexity in propagating a fast wind on large scales. our current data suggest a combination of photoionization and resonant scattering as powering mechanisms of the ly α emission. we discover the first z ∼ 3 elan, confirming a very low probability ({∼ }1{{ per cent}}) of occurrence of such systems at these redshifts. finally, we discuss the redshift evolution currently seen in extended ly α emission around radio-quiet quasars from z ∼ 3 to z ∼ 2, concluding that it is possibly linked to a decrease of cool gas mass within the circumgalactic medium of quasars from z ∼ 3 to z ∼ 2, and thus to the balance of cool versus hot media. overall, qso museum opens the path to statistical surveys targeting the gas phases in quasars' haloes along cosmic times. | qso museum i: a sample of 61 extended ly α-emission nebulae surrounding z ∼ 3 quasars |
quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidence is still scarce and debated. here we present early release science jwst nirspec ifu observations of the z = 1.59 prototypical obscured active galactic nucleus (agn) xid2028: this target represents a unique test case for studying quasar feedback at the peak epoch of agn-galaxy co-evolution because extensive multi-wavelength coverage is available and a massive and extended outflow is detected in the ionised and molecular components. with the unprecedented sensitivity and spatial resolution of the jwst, the nirspec dataset reveals a wealth of structures in the ionised gas kinematics and morphology that were previously hidden in the seeing-limited ground-based data. in particular, we find evidence of an interaction between the interstellar medium of the galaxy and the quasar-driven outflow and radio jet that produces an expanding bubble from which the fast and extended wind detected in previous observations emerges. the new observations confirm the complex interplay between the agn jet, wind and the interstellar medium of the host galaxy, highlighting the role of low-luminosity radio jets in agn feedback. they also clearly show the new window that nirspec opens for detailed studies of feedback at high redshift. | bubbles and outflows: the novel jwst/nirspec view of the z = 1.59 obscured quasar xid2028 |
the mean free path of ionizing photons, λ mfp, is a critical parameter for modeling the intergalactic medium (igm) both during and after reionization. we present direct measurements of λ mfp from qso spectra over the redshift range 5 < z < 6, including the first measurements at z ≃ 5.3 and 5.6. our sample includes data from the xqr-30 vlt large program, as well as new keck/esi observations of qsos near z ~ 5.5, for which we also acquire new [c ii] 158 μm redshifts with alma. by measuring the lyman continuum transmission profile in stacked qso spectra, we find ${\lambda }_{\mathrm{mfp}}={9.33}_{-1.80}^{+2.06}$ , ${5.40}_{-1.40}^{+1.47}$ , ${3.31}_{-1.34}^{+2.74}$ , and ${0.81}_{-0.48}^{+0.73}$ pmpc at z = 5.08, 5.31, 5.65, and 5.93, respectively. our results demonstrate that λ mfp increases steadily and rapidly with time over 5 < z < 6. notably, we find that λ mfp deviates significantly from predictions based on a fully ionized and relaxed igm as late as z = 5.3. by comparing our results to model predictions and indirect λ mfp constraints based on igm lyα opacity, we find that the evolution of λ mfp is consistent with scenarios wherein the igm is still undergoing reionization and/or retains large fluctuations in the ionizing uv background well below redshift 6. | probing ultralate reionization: direct measurements of the mean free path over 5 < z < 6 |
the cosmic ionizing emissivity from star-forming galaxies has long been anchored to uv luminosity functions. here, we introduce an emissivity framework based on lyα emitters (laes), which naturally hones in on the subset of galaxies responsible for the ionizing background due to the intimate connection between production and escape of lyα and lyc photons. using constraints on the escape fractions of bright laes (llyα > 0.2l*) at z ≈ 2 obtained from resolved lyα profiles, and arguing for their redshift-invariance, we show that: (i) quasars and laes together reproduce the relatively flat emissivity at z ≈ 2-6, which is non-trivial given the strong evolution in both the star formation density and quasar number density at these epochs and (ii) laes produce late and rapid reionization between z ≈ 6-9 under plausible assumptions. within this framework, the >10 × rise in the uv population-averaged fesc between z ≈ 3-7 naturally arises due to the same phenomena that drive the growing lae fraction with redshift. generally, a lae dominated emissivity yields a peak in the distribution of the ionizing budget with uv luminosity as reported in latest simulations. using our adopted parameters ($f_{\rm {esc}}=50{{\ \rm per\ cent}}$, ξion = 1025.9 hz erg-1 for half the bright laes), a highly ionizing minority of galaxies with muv < -17 accounts for the entire ionizing budget from star-forming galaxies. rapid flashes of lyc from such rare galaxies produce a 'disco' ionizing background. we conclude proposing tests to further develop our suggested lyα-anchored formalism. | (re)solving reionization with lyα: how bright lyα emitters account for the z ≈ 2-8 cosmic ionizing background |
aims: the sinfoni survey for unveiling the physics and effect of radiative feedback (super) aims to trace and characterise ionised gas outflows and their impact on star formation in a statistical sample of x-ray selected active galactic nuclei (agn) at z ∼ 2. we present the first sinfoni results for a sample of 21 type 1 agn spanning a wide range in bolometric luminosity (log lbol = 45.4-47.9 erg s-1). the main aims of this paper are to determine the extension of the ionised gas, characterise the occurrence of agn-driven outflows, and link the properties of such outflows with those of the agn.methods: we used adaptive optics-assisted sinfoni observations to trace ionised gas in the extended narrow line region using the [o iii] λ5007 line. we classified a target as hosting an outflow if its non-parametric velocity of the [o iii] line, w80, was larger than 600 km s-1. we studied the presence of extended emission using dedicated point-spread function (psf) observations, after modelling the psf from the balmer lines originating from the broad line region.results: we detect outflows in all the type 1 agn sample based on the w80 value from the integrated spectrum, which is in the range ∼650-2700 km s-1. there is a clear positive correlation between w80 and the agn bolometric luminosity (> 99% correlation probability), and the black hole mass (98% correlation probability). a comparison of the psf and the [o iii] radial profile shows that the [o iii] emission is spatially resolved for ∼35% of the type 1 sample and the outflows show an extension up to ∼6 kpc. the relation between maximum velocity and the bolometric luminosity is consistent with model predictions for shocks from an agn-driven outflow. the escape fraction of the outflowing gas increases with the agn luminosity, although for most galaxies, this fraction is less than 10%. | super. ii. spatially resolved ionised gas kinematics and scaling relations in z ∼ 2 agn host galaxies |
prevalent around luminous accreting black holes, thin discs are challenging to resolve in numerical simulations. when the disc and black hole angular momentum vectors are misaligned, the challenge becomes extreme, requiring adaptive meshes to follow the disc proper as it moves through the computational grid. with our new high-performance general relativistic magnetohydrodynamic (grmhd) code h-amr, we have simulated the thinnest accretion disc to date, of aspect ratio h/r ≈ 0.03 ≈ 1.7°, around a rapidly spinning (a ≈ 0.9) black hole, using a cooling function. initially tilted at 10°, the disc warps inside ∼5 rg into alignment with the black hole, where rg is the gravitational radius. this is the first demonstration of bardeen-petterson alignment in mhd with viscosity self-consistently generated by magnetized turbulence. the disc develops a low-density high-viscosity (αeff ∼ 1.0) magnetic-pressure-dominated inner region at r ≲ 25rg that rapidly empties itself into the black hole. this inner region may, in reality, due to thermal decoupling of ions and electrons, evaporate into a radiatively inefficient accretion flow if, as we propose, the cooling time exceeds the accretion time set by the order unity effective viscosity. we furthermore find the unexpected result that even our very thin disc can sustain large-scale vertical magnetic flux on the black hole, which launches powerful relativistic jets that carry 20-50 per cent of the accretion power along the angular momentum vector of the outer tilted disc, providing a potential explanation for the origin of jets in radio-loud quasars. | bardeen-petterson alignment, jets, and magnetic truncation in grmhd simulations of tilted thin accretion discs |
dark matter (dm) could be a relic of freeze-in through a light mediator, where the dm is produced by extremely feeble, ir-dominated processes in the thermal standard model plasma. in the simplest viable models with dm lighter than 1 mev, the dm has a small effective electric charge and is born with a nonthermal phase-space distribution. this dm candidate would cause observable departures from standard cosmological evolution. in this work, we combine data from the cosmic microwave background (cmb), lyman-α forest, quasar lensing, stellar streams, and milky way satellite abundances to set limits on freeze-in dm masses up to ∼20 kev , with the exact constraint depending on whether the dm thermalizes in its own sector. we perform forecasts for the cmb-s4 experiment, the hydrogen epoch of reionization array, and the vera rubin observatory, finding that freeze-in dm masses up to ∼80 kev can be explored. | cosmology of sub-mev dark matter freeze-in |
we present the quasar luminosity function (lf) at z = 7, measured with 35 spectroscopically confirmed quasars at 6.55 < z < 7.15. the sample of 22 quasars from the subaru high-z exploration of low-luminosity quasars (shellqs) project, combined with 13 brighter quasars in the literature, covers an unprecedentedly wide range of rest-frame ultraviolet magnitudes over -28 < m 1450 < -23. we found that the binned lf flattens significantly toward the faint end populated by the shellqs quasars. a maximum likelihood fit to a double power-law model has a break magnitude ${m}_{1450}^{* }=-{25.60}_{-0.30}^{+0.40}$ , a characteristic density ${{\rm{\phi }}}^{* }={1.35}_{-0.30}^{+0.47}$ gpc-3 mag-1, and a bright-end slope $\beta =-{3.34}_{-0.57}^{+0.49}$ , when the faint-end slope is fixed to α = -1.2 as observed at z ≤ 6. the overall lf shape remains remarkably similar from z = 4 to 7, while the amplitude decreases substantially toward higher redshifts, with a clear indication of an accelerating decline at z ≥ 6. the estimated ionizing photon density, 1048.2±0.1 s-1 mpc-3, is less than 1% of the critical rate to keep the intergalactic medium ionized at z = 7, and thus indicates that quasars are not a major contributor to cosmic reionization. | quasar luminosity function at z = 7 |
models and observations suggest that both the power and effects of agn feedback should be maximised in hyper-luminous (lbol > 1047 erg s-1) quasars, i.e. objects at the brightest end of the agn luminosity function. in this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of wise/sdss selected hyper-luminous (wissh) broad-line quasars at z ≈ 1.5-5. the wissh quasars project has been designed to reveal the most energetic agn-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme agn luminosities, i.e. lbol 1047 - 1048 erg s-1. we present near-infrared, long-slit lbt/luci1 spectroscopy of five wissh quasars at z ≈ 2.3 - 3.5, showing prominent [oiii] emission lines with broad (fwhm 1200-2200 km s-1) and skewed profiles. the luminosities of these broad [oiii] wings are the highest measured so far, with l[oiii]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates ṁ ≳ 1700m⊙ yr-1 and kinetic powers ėkin ≳ 1045 erg s-1. although these estimates are affected by large uncertainties because of the use of [oiii] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the agn is highly efficient at pushing large amounts of ionised gas outwards. furthermore, the mechanical outflow luminosities measured for wissh quasars correspond to higher percentages ( 1-3%) of lbol than those derived for agn with lower lbol. our targets host very massive (mbh ≳ 2 × 109m⊙) black holes that are still accreting at a high rate (i.e. a factor of 0.4-3 of the eddington limit). these findings clearly demonstrate that wissh quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (smbh) mass functions and revealing powerful ionised outflows that are able to affect the evolution of their host galaxies. | the wissh quasars project. i. powerful ionised outflows in hyper-luminous quasars |
almost 10 yr of γ-ray observations with the fermi large area telescope have revealed extreme γ-ray outbursts from flat spectrum radio quasars (fsrqs), temporarily making these objects the brightest γ-ray emitters in the sky. yet, the location and mechanisms of the γ-ray emission remain elusive. we characterize long-term γ-ray variability and the brightest γ-ray flares of six fsrqs. consecutively zooming in on the brightest flares, which we identify in an objective way through bayesian blocks and a hill-climbing algorithm, we find variability on subhour timescales and as short as minutes for two sources in our sample (3c 279 and cta 102) and weak evidence for variability at timescales less than the fermi satellite’s orbit of 95 minutes for pks 1510-089 and 3c 454.3. this suggests extremely compact emission regions in the jet. we do not find any signs of γ-ray absorption in the broad-line region (blr), which indicates that γ-rays are produced at distances greater than hundreds of gravitational radii from the central black hole. this is further supported by a cross-correlation analysis between γ-ray and radio/millimeter light curves, which is consistent with γ-ray production at the same location as the millimeter core for 3c 273, cta 102, and 3c 454.3. the inferred locations of the γ-ray production zones are still consistent with the observed decay times of the brightest flares if the decay is caused by external compton scattering with blr photons. however, the minute-scale variability is challenging to explain in such scenarios. | characterizing the gamma-ray variability of the brightest flat spectrum radio quasars observed with the fermi lat |
quiescent galaxies with little or no ongoing star formation dominate the population of galaxies with masses above 2 × 1010 times that of the sun; the number of quiescent galaxies has increased by a factor of about 25 over the past ten billion years (refs 1, 2, 3, 4). once star formation has been shut down, perhaps during the quasar phase of rapid accretion onto a supermassive black hole, an unknown mechanism must remove or heat the gas that is subsequently accreted from either stellar mass loss or mergers and that would otherwise cool to form stars. energy output from a black hole accreting at a low rate has been proposed, but observational evidence for this in the form of expanding hot gas shells is indirect and limited to radio galaxies at the centres of clusters, which are too rare to explain the vast majority of the quiescent population. here we report bisymmetric emission features co-aligned with strong ionized-gas velocity gradients from which we infer the presence of centrally driven winds in typical quiescent galaxies that host low-luminosity active nuclei. these galaxies are surprisingly common, accounting for as much as ten per cent of the quiescent population with masses around 2 × 1010 times that of the sun. in a prototypical example, we calculate that the energy input from the galaxy’s low-level active supermassive black hole is capable of driving the observed wind, which contains sufficient mechanical energy to heat ambient, cooler gas (also detected) and thereby suppress star formation. | suppressing star formation in quiescent galaxies with supermassive black hole winds |
the c ivλλ1498,1501 broad emission line is visible in optical spectra to redshifts exceeding z ∼ 5. c iv has long been known to exhibit significant displacements to the blue and these `blueshifts' almost certainly signal the presence of strong outflows. as a consequence, single-epoch virial black hole (bh) mass estimates derived from c iv velocity widths are known to be systematically biased compared to masses from the hydrogen balmer lines. using a large sample of 230 high-luminosity (lbol = 1045.5-1048 erg s-1), redshift 1.5 < z < 4.0 quasars with both c iv and balmer line spectra, we have quantified the bias in c iv bh masses as a function of the c iv blueshift. c iv bh masses are shown to be a factor of 5 larger than the corresponding balmer-line masses at c iv blueshifts of 3000 km s-1and are overestimated by almost an order of magnitude at the most extreme blueshifts, ≳5000 km s-1. using the monotonically increasing relationship between the c iv blueshift and the mass ratio bh(c iv)/bh(hα), we derive an empirical correction to all c iv bh masses. the scatter between the corrected c iv masses and the balmer masses is 0.24 dex at low c iv blueshifts (∼0 km s-1) and just 0.10 dex at high blueshifts (∼3000 km s-1), compared to 0.40 dex before the correction. the correction depends only on the c iv line properties - i.e. full width at half-maximum and blueshift - and can therefore be applied to all quasars where c iv emission line properties have been measured, enabling the derivation of unbiased virial bh-mass estimates for the majority of high-luminosity, high-redshift, spectroscopically confirmed quasars in the literature. | correcting c iv-based virial black hole masses |
bright quasars, powered by accretion onto billion-solar-mass black holes, already existed at the epoch of reionization, when the universe was 0.5-1 billion years old1. how these black holes formed in such a short time is the subject of debate, particularly as they lie above the correlation between black-hole mass and galaxy dynamical mass2,3 in the local universe. what slowed down black-hole growth, leading towards the symbiotic growth observed in the local universe, and when this process started, has hitherto not been known, although black-hole feedback is a likely driver4. here we report optical and near-infrared observations of a sample of quasars at redshifts 5.8 ≲ z ≲ 6.6. about half of the quasar spectra reveal broad, blueshifted absorption line troughs, tracing black-hole-driven winds with extreme outflow velocities, up to 17% of the speed of light. the fraction of quasars with such outflow winds at z ≳ 5.8 is ≈2.4 times higher than at z ≈ 2-4. we infer that outflows at z ≳ 5.8 inject large amounts of energy into the interstellar medium and suppress nuclear gas accretion, slowing down black-hole growth. the outflow phase may then mark the beginning of substantial black-hole feedback. the red optical colours of outflow quasars at z ≳ 5.8 indeed suggest that these systems are dusty and may be caught during an initial quenching phase of obscured accretion5. | suppression of black-hole growth by strong outflows at redshifts 5.8-6.6 |
we analyse some open debates in cosmology in light of the most updated quasar (qso) sample, covering a wide redshift range up to $\mathit{ z}$ ~ 7.5, combined with type ia supernovae (sne) and baryon acoustic oscillations (baos). indeed, extending the cosmological analyses with high-redshift data is key to distinguishing between different cosmological models that are degenerate at low redshifts, and allowing better constraints on a possible dark energy (de) evolution. also, we discuss combinations of bao, sne, and qso data to understand their compatibility and implications for extensions of the standard cosmological model. specifically, we consider a flat and non-flat λcdm cosmology, a flat and non-flat de model with a constant de equation of state parameter (w), and four flat de models with variable w, namely the chevallier-polarski-linder and jassal-bagla-padmanabhan models, and an 'exponential', and barboza-alcaniz parametrizations. we find that a joint analysis of qso+sne with bao is only possible in the context of a flat universe. indeed bao confirms the flatness condition assuming a curved geometry, whilst sne + qso show evidence of a closed space. we also find ωm,0 = 0.3 in all data sets assuming a flat λcdm model. yet, all the other models show a statistically significant deviation at 2-3 σ with the combined sne + so + bao data set. in the models where de density evolves with time, sne + qso + bao data always prefer ωm,0 > 0.3, w0 < -1 and wa > 0. this de phantom behaviour is mainly driven by sne + qso, while bao are closer to the flat λcdm model. | quasar cosmology: dark energy evolution and spatial curvature |
we quantify the presence of lyα damping wing absorption from a partially neutral intergalactic medium (igm) in the spectrum of the z = 7.08 qso, ulasj1120+0641. using a bayesian framework, we simultaneously account for uncertainties in: (i) the intrinsic qso emission spectrum; and (ii) the distribution of cosmic h i patches during the epoch of reionization (eor). for (i), we use a new intrinsic lyα emission line reconstruction method, sampling a covariance matrix of emission line properties built from a large data base of moderate-z qsos. for (ii), we use the evolution of 21-cm structure (eos; mesinger et al.) simulations, which span a range of physically motivated eor models. we find strong evidence for the presence of damping wing absorption redward of lyα (where there is no contamination from the lyα forest). our analysis implies that the eor is not yet complete by z = 7.1, with the volume-weighted igm neutral fraction constrained to \bar{x}_{h i} = 0.40^{+0.21 }_{ -0.19} at 1σ (\bar{x}_{h i} = 0.40^{+0.41 }_{ -0.32} at 2σ). this result is insensitive to the eor morphology. our detection of significant neutral h i in the igm at z = 7.1 is consistent with the latest planck 2016 measurements of the cmb thompson scattering optical depth. | are we witnessing the epoch of reionisation at z = 7.1 from the spectrum of j1120+0641? |
we present a measurement of the 1d lyα forest flux power spectrum, using the complete baryon oscillation spectroscopic survey (boss) and first extended-boss (eboss) quasars at zqso > 2.1, corresponding to the fourteenth data release (dr14) of the sloan digital sky survey (sdss). our results cover thirteen bins in redshift from zlyα = 2.2 to 4.6, and scales up to k = 0.02 (km/s)-1. from a parent sample of 180,413 visually inspected spectra, we selected the 43,751 quasars with the best quality; this data set improves the previous result from the ninth data release (dr9), both in statistical precision (achieving a reduction by a factor of two) and in redshift coverage. we also present a thorough investigation of identified sources of systematic uncertainties that affect the measurement. the resulting 1d power spectrum of this work is in excellent agreement with the one from the boss dr9 data. | the one-dimensional power spectrum from the sdss dr14 lyα forests |
we study the interaction of feedback from active galactic nuclei (agn) and a multiphase interstellar medium (ism), in simulations including explicit stellar feedback, multiphase cooling, accretion-disc winds, and compton heating. we examine radii ∼0.1-100 pc around a black hole (bh), where the accretion rate on to the bh is determined and where agn-powered winds and radiation couple to the ism. we conclude: (1) the bh accretion rate is determined by exchange of angular momentum between gas and stars in gravitational instabilities. this produces accretion rates ∼0.03-1 m⊙ yr-1, sufficient to power luminous agn. (2) the gas disc in the galactic nucleus undergoes an initial burst of star formation followed by several million years where stellar feedback suppresses the star formation rate (sfr). (3) agn winds injected at small radii with momentum fluxes ∼lagn/c couple efficiently to the ism and have dramatic effects on ism properties within ∼100 pc. agn winds suppress the nuclear sfr by factors ∼10-30 and bh accretion rate by factors ∼3-30. they increase the outflow rate from the nucleus by factors ∼10, consistent with observational evidence for galaxy-scale agn-driven outflows. (4) with agn feedback, the predicted column density distribution to the bh is consistent with observations. absent agn feedback, the bh is isotropically obscured and there are not enough optically thin sightlines to explain type-i agn. a `torus-like' geometry arises self-consistently as agn feedback evacuates gas in polar regions. | stellar and quasar feedback in concert: effects on agn accretion, obscuration, and outflows |
we study metal depletion due to dust in the interstellar medium (ism) to infer the properties of dust grains and characterize the metal and dust content of galaxies down to low metallicity and intermediate redshift z. we provide metal column densities and abundances of a sample of 70 damped lyman-α absorbers (dlas) towards quasars, observed at high spectral resolution with the very large telescope (vlt) ultraviolet and visual echelle spectrograph (uves). this is the largest sample of phosphorus abundances measured in dlas so far. we use literature measurements for galactic clouds to cover the high-metallicity end. we discover tight (scatter ≲ 0.2 dex) correlations between [zn/fe] and the observed relative abundances from dust depletion. this implies that grain growth in the ism is an important process of dust production. these sequences are continuous in [zn/fe] from dust-free to dusty dlas, and to galactic clouds, suggesting that the availability of refractory metals in the ism is crucial for dust production, regardless of the star formation history. we observe [s/zn] up to 0.25 dex in dlas, which is broadly consistent with galactic stellar abundances. furthermore, we find a good agreement between the nucleosynthetic pattern of galactic halo stars and our observations of the least dusty dlas. this supports recent star formation in low-metallicity dlas. the derived depletions of zn, o, p, s, si, mg, mn, cr, and fe correlate with [zn/fe], with steeper slopes for more refractory elements. p is mostly not affected by dust depletion. we present canonical depletion patterns to be used as reference in future studies of relative abundances and depletion. we derive the total (dust-corrected) metallicity, typically -2 ≲ [m/h] tot ≲ 0 for dlas, and scattered around solar metallicity for the galactic ism. the dust-to-metal ratio (mathcal{{dtm}}) increases with metallicity, again supporting the importance of grain growth for dust production. the dust extinction av derived from the depletion is typically <0.2 mag in dlas. finally, we derive elemental abundances in dust, which is key to understanding the dust composition and its evolution. we observe similar abundances of mg, si, and fe in dust; this suggests that grain species such as pyroxenes and iron oxides are more important than olivine, but this needs to be confirmed by more detailed analysis. overall, we characterize dust depletion, nucleosynthesis, and dust-corrected metallicity in dlas, providing a unified picture from low-metallicity systems to the galactic ism. based on observations carried out at the european organisation for astronomical research in the southern hemisphere under eso programmes 065.p-0038, 065.o-0063, 066.a-0624, 067.a-0078, and 068.a-0600. | dust-depletion sequences in damped lyman-α absorbers. a unified picture from low-metallicity systems to the galaxy |
we present a new investigation of the intergalactic medium (igm) near the end of reionization using "dark gaps" in the lyα forest. using spectra of 55 qsos at z em > 5.5, including new data from the xqr-30 vlt large programme, we identify gaps in the lyα forest where the transmission averaged over 1 comoving h -1 mpc bins falls below 5%. nine ultralong (l > 80 h -1 mpc) dark gaps are identified at z < 6. in addition, we quantify the fraction of qso spectra exhibiting gaps longer than 30 h -1 mpc, f 30, as a function of redshift. we measure f 30 ≃ 0.9, 0.6, and 0.15 at z = 6.0, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to z ≃5.3. comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. models wherein the igm is essentially fully reionized that retain large-scale fluctuations in the ionizing uv background at z ≲6 are also potentially consistent with the data. overall, our results suggest that signatures of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the igm until at least z ≃ 5.3. | chasing the tail of cosmic reionization with dark gap statistics in the lyα forest over 5 < z < 6 |
this is the fourth paper in a series of publications aiming at discovering quasars at the epoch of reionization. in this paper, we expand our search for z ∼ 7 quasars to the footprint of the dark energy survey (des) data release one (dr1), covering ∼5000 deg2 of a new area. we select z ∼ 7 quasar candidates using deep optical, near-infrared (near-ir) and mid-infrared (mid-ir) photometric data from the des dr1, the vista hemisphere survey, the vista kilo-degree infrared galaxy survey, the ukirt infrared deep sky surveys—large area survey (ulas), and the unblurred coadds from the wide-field infrared survey explore (wise) images (unwise). the inclusion of des and unwise photometry allows the search to reach ∼1 mag fainter, comparing to our z ≳ 6.5 quasar survey in the northern sky. we report the initial discovery and spectroscopic confirmation of six new luminous quasars at z > 6.4, including an object at z = 7.02, the fourth quasar yet known at z > 7, from a small fraction of candidates observed thus far. based on the recent measurement of z ∼ 6.7 quasar luminosity function using the quasar sample from our survey in the northern sky, we estimate that there will be ≳55 quasars at z > 6.5 at m 1450 < -24.5 in the full des footprint. | exploring reionization-era quasars. iv. discovery of six new z ≳ 6.5 quasars with des, vhs, and unwise photometry |
dust-obscured galaxies are thought to represent an early evolutionary phase of massive galaxies in which the active galactic nucleus (agn) is still deeply buried in significant amounts of dusty material and its emission is strongly suppressed. the unprecedented sensitivity of the james webb space telescope enables us for the first time to detect the rest-frame optical emission of heavily obscured agn and unveil the properties of the hidden accreting super-massive black holes (bhs). in this work, we present the jwst/nirspec ifs data of aless073.1, a massive, dusty, star-forming galaxy at $z = 4.76$ hosting an agn at its center. the detection of a very broad $h_\alpha$ emission associated with the broad line region (blr) confirms the presence of a bh ($\log(m_{bh}/m_\odot)>8.7$) accreting at less than 15\% of its eddington limit and classifies the target as a type 1 agn. the rest-frame optical emission lines also reveal a fast ionized gas outflow marginally resolved in the galaxy center. the high sensitivity of nirspec allows us to perform the kinematic analysis of the narrow h$\alpha$ component which indicates that the warm ionized gas velocity field is consistent with disk rotation. we also find that, in the innermost nuclear regions ($< 1.5$ kpc), the intrinsic velocity dispersion of the disk reaches $\sim 150$ km/s, $\sim 2-3$ times higher than the velocity dispersion inferred from the [cii] 158$\mu$m line tracing mostly cold gas. since, at large radii, the velocity dispersion of the warm and cold gas are comparable, we conclude that the outflows are injecting turbulence in the warm ionized gas in the central region, but they are not sufficiently powerful to disrupt the dense gas and quench star formation. these findings support the scenario that dust-obscured galaxies represent the evolutionary stage preceding the unobscured quasar when all gas and dust are removed from the host. | ga-nifs: early-stage feedback in a heavily obscured agn at $z=4.76$ |
we present band 6 alma observations of a heavily obscured radio-loud (l1.4 ghz = 1025.4 w hz-1) active galactic nucleus (agn) candidate at zphot = 6.83 ± 0.06 found in the 1.5 deg2 cosmos field. the alma data reveal detections of exceptionally strong [c ii]158 $\mu$m (z[c ii] = 6.8532) and underlying dust continuum emission from this object (cos-87259), where the [c ii] line luminosity, line width, and 158 $\mu$m continuum luminosity are comparable to those seen from z ~ 7 sub-mm galaxies and quasar hosts. the 158 $\mu$m continuum detection suggests a total infrared luminosity of $9\times 10^{12}\, \mathrm{ l}_\odot$ with corresponding very large obscured star formation rate (1300 m⊙ yr-1) and dust mass ($2\times 10^9\, \mathrm{ m}_\odot$). the strong break seen between the vircam and irac photometry perhaps suggests that cos-87259 is an extremely massive reionization-era galaxy with $m_\ast \approx 1.7\times 10^{11}\, \mathrm{ m}_\odot$. moreover, the mips, pacs, and spire detections imply that this object harbours an agn that is heavily obscured ($\tau _{_{\mathrm{9.7\,\mu m}}}=2.3$) with a bolometric luminosity of approximately $5\times 10^{13}\, \mathrm{ l}_\odot$. such a very high agn luminosity suggests that this object is powered by an ≈1.6 × 10$^9\, \mathrm{ m}_\odot$ black hole if accreting near the eddington limit, and is effectively a highly obscured version of an extremely ultraviolet (uv)-luminous (m1450 ≈ -27.3) z ~ 7 quasar. notably, these z ~ 7 quasars are an exceedingly rare population (~0.001 deg-2), while cos-87259 was identified over a relatively small field. future very wide area surveys with e.g. roman and euclid have the potential to identify many more extremely red yet uv-bright z ≳ 7 objects similar to cos-87259, providing richer insight into the occurrence of intense obscured star formation and supermassive black hole growth among this population. | alma confirmation of an obscured hyperluminous radio-loud agn at z = 6.853 associated with a dusty starburst in the 1.5 deg2 cosmos field |
we present the one-dimensional ly α forest power spectrum measurement using the first data provided by the dark energy spectroscopic instrument (desi). the data sample comprises 26 330 quasar spectra, at redshift z > 2.1, contained in the desi early data release and the first 2 months of the main survey. we employ a fast fourier transform (fft) estimator and compare the resulting power spectrum to an alternative likelihood-based method in a companion paper. we investigate methodological and instrumental contaminants associated with the new desi instrument, applying techniques similar to previous sloan digital sky survey (sdss) measurements. we use synthetic data based on lognormal approximation to validate and correct our measurement. we compare our resulting power spectrum with previous sdss and high-resolution measurements. with relatively small number statistics, we successfully perform the fft measurement, which is already competitive in terms of the scale range. at the end of the desi survey, we expect a five times larger ly α forest sample than sdss, providing an unprecedented precise one-dimensional power spectrum measurement. | the dark energy spectroscopic instrument: one-dimensional power spectrum from first ly α forest samples with fast fourier transform |
the origin and properties of the initial black hole seeds that grow to produce the observed population of accreting sources remain to be determined. it is a challenge to uniquely disentangle signatures of seeding from fuelling and dynamics that shapes the assembly history of growing black holes. to address this, we use a semi-analytic model developed to track the growth of supermassive black holes adopting multiple prescriptions for accretion. in contrast with earlier treatments, we explore the interplay between seeding models and two accretion modes. we find that signatures of the initial seeding do survive in the following observational probes: the black hole occupation fraction; contribution to the unresolved x-ray background; low-luminosity and high-redshift luminosity functions; and gravitational wave event signatures. we find that the behaviour of the low-mass end of the m•-σ relation is dominated by uncertainties in the adopted accretion prescriptions and does not offer clear discrimination between seeding models. we make concrete predictions for future surveys, particularly for the lynx x-ray surveyor and laser interferometer space antenna (lisa) mission, which will each provide different and yet strong constraints on the seed population. black hole coalescences detected by lisa and high-redshift quasar luminosity functions observed by lynx will offer the sharpest seeding discriminants. although the signatures of the black hole seeding mechanism that persist remain linked to our understanding of black hole accretion and dynamics, we offer new insights on how these upcoming multiwavelength observations could be leveraged to effectively disentangle them. | the observational signatures of supermassive black hole seeds |
we present 15 ghz stacked vlba images of 373 jets associated with active galactic nuclei (agns) having at least five observing epochs within a 20 yr time interval 1994-2015 from the monitoring of jets in active galactic nuclei with vlba experiments (mojave) programme and/or its precursor, the 2-cm vlba survey. these data are supplemented by 1.4 ghz single-epoch vlba observations of 135 mojave agns to probe larger scale jet structures. the typical jet geometry is found to be close to conical on scales from hundreds to thousands of parsecs, while a number of galaxies show quasi-parabolic streamlines on smaller scales. a true jet geometry in a considerable fraction of agns appears only after stacking epochs over several years. the jets with significant radial accelerated motion undergo more active collimation. we have analysed total intensity jet profiles transverse to the local jet ridgeline and derived both apparent and intrinsic opening angles of the flows, with medians of 21.5° and 1.3°, respectively. the fermi lat-detected gamma-ray agns in our sample have, on average, wider apparent and narrower intrinsic opening angle, and smaller viewing angle than non-lat-detected agns. we have established a highly significant correlation between the apparent opening angle and gamma-ray luminosity, driven by doppler beaming and projection effects. | mojave - xiv. shapes and opening angles of agn jets |
the prevalence and properties of kiloparsec-scale outflows in nearby type 1 quasars have been the subject of little previous attention. this work presents gemini integral field spectroscopy of 10 type 1 radio-quiet quasars at z< 0.3. the excellent image quality, coupled with a new technique to remove the point-spread function using spectral information, allows the fitting of the underlying host on a spaxel-by-spaxel basis. fits to stars, line-emitting gas, and interstellar absorption show that 100% of the sample hosts warm ionized and/or cool neutral outflows with spatially averaged velocities (< {v}98 % > \equiv < v+2σ > ) of 200-1300 {km} {{{s}}}-1 and peak velocities (maximum {v}98 % ) of 500-2600 {km} {{{s}}}-1. these minor-axis outflows are powered primarily by the central active galactic nucleus, reach scales of 3-12 kpc, and often fill the field of view. including molecular data and type 2 quasar measurements, nearby quasars show a wide range in mass outflow rates ({dm}/{dt}=1 to > 1000 {m}⊙{{yr}}-1) and momentum boosts [(c {dp}/{dt})/{l}{agn}=0.01{--}20]. after extending the mass scale to seyferts, dm/dt and de/dt correlate with black hole mass ({dm}/{dt}∼ {m}{bh}0.7+/- 0.3 and {de}/{dt}∼ {m}{bh}1.3+/- 0.5). thus, the most massive black holes in the local universe power the most massive and energetic quasar-mode winds. | quasar-mode feedback in nearby type 1 quasars: ubiquitous kiloparsec-scale outflows and correlations with black hole properties |
strong lensing provides a powerful means of investigating the nature of dark matter as it probes dark matter structure on sub-galactic scales. we present an extension of a forward modelling framework that uses flux ratios from quadruply imaged quasars (quads) to measure the shape and amplitude of the halo mass function, including line-of-sight (los) haloes and main deflector subhaloes. we apply this machinery to 50 mock lenses - roughly the number of known quads - with warm dark matter (wdm) mass functions exhibiting free-streaming cut-offs parametrized by the half-mode mass mhm. assuming cold dark matter (cdm), we forecast bounds on mhm and the corresponding thermal relic particle masses over a range of tidal destruction severity, assuming a particular wdm mass function and mass-concentration relation. with significant tidal destruction, at 2σ we constrain m_{hm}< 10^{7.9} \left(10^{8.4}\right) m_{\odot }, or a 4.4 (3.1) kev thermal relic, with image flux uncertainties from measurements and lens modelling of 2{{ per cent}} \left(6{{ per cent}}\right). with less severe tidal destruction we constrain m_{hm}< 107 \left(10^{7.4}\right) m_{\odot }, or an 8.2 (6.2) kev thermal relic. if dark matter is warm, with m_{hm} = 10^{7.7} m_{\odot } (5.1 kev), we would favour wdm with m_{hm} > 10^{7.7} m_{\odot } over cdm with relative likelihoods of 22:1 and 8:1 with flux uncertainties of 2{{ per cent}} and 6{{ per cent}}, respectively. these bounds improve over those obtained by modelling only main deflector subhaloes because los objects produce additional flux perturbations, especially for high-redshift systems. these results indicate that ∼50 quads can conclusively differentiate between wdm and cdm. | probing dark matter structure down to 107 solar masses: flux ratio statistics in gravitational lenses with line-of-sight haloes |
previous studies have noted difficulties in modelling the highest opacities of the z > 5.5 ly α forest, epitomized by the extreme lyα trough observed towards quasar ulas j0148 + 0600. one possibility is that the most opaque regions at these redshifts contain significant amounts of neutral hydrogen. this explanation, which abandons the common assumption that reionization ended before z = 6, also reconciles evidence from independent observations of a significantly neutral universe at z = 7.5. here, we explore a model in which the neutral fraction is still ${\approx }10{{\ \rm per\ cent}}$ at z = 5.5. we confirm that this model can account for the observed scatter in ly α forest opacities, as well as the observed ly β transmission in the j0148 trough. we contrast the model with a competing 'earlier' reionization scenario characterized by a short mean free path and large fluctuations in the post-reionization ionizing background. we consider ly α and ly β effective optical depths, their correlations, trough size distributions, dark pixel fractions, the igm thermal history, and spatial distributions of lyman-α emitters around forest sightlines. we find that the models are broadly similar in almost all of these statistics, suggesting that it may be difficult to distinguish between them definitively. we argue that improved constraints on the mean free path and the thermal history at z > 5 could go a long way towards diagnosing the origin of the z > 5.5 opacity fluctuations. | observing the tail of reionization: neutral islands in the z = 5.5 lyman-α forest |
recent observations have shown that the scatter in opacities amongst coeval segments of the ly α forest increases rapidly at z > 5. in this paper, we assess whether the large scatter can be explained by fluctuations in the ionizing background in the post-reionization intergalactic medium. we find that matching the observed scatter at z ≈ 5.5 requires a short spatially averaged mean free path of 〈λmfp912〉 ≲ 15 h- 1 comoving mpc, a factor of ≳3 shorter than direct measurements at z = 5.2. we argue that such rapid evolution in the mean free path is difficult to reconcile with our measurements of the global h i photoionization rate, which stay approximately constant over the interval z ≈ 4.8-5.5. however, we also show that measurements of the mean free path at z > 5 are likely biased towards higher values by the quasar proximity effect. this bias can reconcile the short values of 〈λmfp912〉 that are required to explain the large scatter in opacities. we discuss the implications of this scenario for cosmological reionization. finally, we investigate whether other statistics applied to the z > 5 ly α forest can shed light on the origin of the scatter. compared to a model with a uniform ionizing background, models that successfully account for the scatter lead to enhanced power in the line-of-sight flux power spectrum on scales k ≲0.1 h mpc-1. we find tentative evidence for this enhancement in observations of the high-redshift ly α forest. | large fluctuations in the high-redshift metagalactic ionizing background |
we use idealized 3d hydrodynamic simulations to study the dynamics and thermal structure of the circumgalactic medium (cgm). our simulations quantify the role of cooling, stellar feedback driven galactic winds and cosmological gas accretion in setting the properties of the cgm in dark matter haloes ranging from 1011 to 1012 m⊙. our simulations support a conceptual picture in which the properties of the cgm, and the key physics governing it, change markedly near a critical halo mass of mcrit ≈ 1011.5 m⊙. as in calculations without stellar feedback, above mcrit halo gas is supported by thermal pressure created in the virial shock. the thermal properties at small radii are regulated by feedback triggered when tcool/tff ≲ 10 in the hot gas. below mcrit, however, there is no thermally supported halo and self-regulation at tcool/tff ∼ 10 does not apply. instead, the gas is out of hydrostatic equilibrium and largely supported against gravity by bulk flows (turbulence and coherent inflow/outflow) arising from the interaction between cosmological gas inflow and outflowing galactic winds. in these lower mass haloes, the phase structure depends sensitively on the outflows' energy per unit mass and mass-loading, which may allow measurements of the cgm thermal state to constrain the nature of galactic winds. our simulations account for some of the properties of the multiphase halo gas inferred from quasar absorption line observations, including the presence of significant mass at a wide range of temperatures, and the characteristic o vi and c iv column densities and kinematics. however, we underpredict the neutral hydrogen content of the z ∼ 0 cgm. | the impact of star formation feedback on the circumgalactic medium |
context. the recent early third data release (edr3) from the gaia mission has produced parallaxes for 1.468 × 109 sources with better quality than those reported in the previous data release. nevertheless, there are calibration issues with the data that require corrections to the published values and uncertainties.aims: we want to properly characterize the behavior of the random and systematic uncertainties of the gaia edr3 parallaxes in order to maximize the precision of the derived distances without compromising their accuracy. we also aim to provide a step-by-step procedure for the calculation of distances to stars and stellar clusters when using these parallaxes.methods: we reanalyzed some of the data presented in the calibration papers for quasar and large magellanic cloud (lmc) parallaxes and combine these results with measurements for six bright globular clusters. we calculated the angular covariance of edr3 parallaxes at small separations (up to a few degrees) based on the lmc results and combined it with the results for larger angles using quasars to obtain an approximate analytical formula for the angular covariance over the whole sky. the results for the six globular clusters were used to validate the parallax bias correction as a function of magnitude, color, and ecliptic latitude and to determine the multiplicative constant k used to convert internal uncertainties to external ones.results: the angular covariance at zero separation is estimated to be 106 μas2, yielding a minimum (systematic) uncertainty for edr3 parallaxes of 10.3 μas for individual stars or compact stellar clusters. this value can be slightly reduced for globular clusters that span ≳30' after considering the behavior of the angular covariance of the parallaxes for small separations. a recent parallax bias correction is found to work quite well, except perhaps for the brighter magnitudes, where improvements may be possible. the value of k is found to be 1.1-1.7 and to depend on g. we find that stars with moderately large values of the renormalized unit weight error can still provide useful parallaxes, albeit with larger values of k. we give accurate and precise gaia edr3 distances to the six globular clusters, and for the specific case of 47 tuc we are able to beat the angular covariance limit through the use of the background small magellanic cloud as a reference and derive a high-precision distance of 4.53 ± 0.06 kpc. finally, a recipe for the derivation of distances to stars and stellar clusters using gaia edr3 parallaxes is given. | validation of the accuracy and precision of gaia edr3 parallaxes with globular clusters |
we use high-quality, medium-resolution hubble space telescope/cosmic origins spectrograph (hst/cos) observations of 82 uv-bright active galactic nuclei (agns) at redshifts zagn < 0.85 to construct the largest survey of the low-redshift intergalactic medium (igm) to date: 5138 individual extragalactic absorption lines in h i and 25 different metal-ion species grouped into 2611 distinct redshift systems at zabs < 0.75 covering total redshift pathlengths δzh i = 21.7 and δzo vi = 14.5. our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. the cumulative column density distribution of h i systems can be parametrized d{ n }(\gt n)/{dz} = {c}14{(n/{10}14{{cm}}-2)}-(β -1), with c14 = 25 ± 1 and β = 1.65 ± 0.02. this distribution is seen to evolve both in amplitude, {c}14\propto {(1+z)}2.3+/- 0.1, and slope β(z) = 1.75-0.31 z for z ≤ 0.47. we observe metal lines in 418 systems, and find that the fraction of igm absorbers detected in metals is strongly dependent on {n}{{h}{{i}}}. the distribution of o vi absorbers appears to evolve in the same sense as the lyα forest. we calculate contributions to ωb from different components of the low-z igm and determine the lyα decrement as a function of redshift. igm absorbers are analyzed via a two-point correlation function in velocity space. we find substantial clustering of h i absorbers on scales of δv = 50-300 km s-1 with no significant clustering at δv ≳ 1000 km s-1. splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, nh i ≳ 1013.5 cm-2, metal-bearing igm systems. the full catalog of absorption lines and fully reduced spectra is available via the mikulski archive for space telescopes (mast) as a high-level science product at http://archive.stsci.edu/prepds/igm/. based on observations made with the nasa/esa hubble space telescope, obtained from the data archive at the space telescope science institute. stsci is operated by the association of universities for research in astronomy, inc. under nasa contract nas5-26555. | an hst/cos survey of the low-redshift intergalactic medium. i. survey, methodology, and overall results |
massive black holes are fundamental constituents of our cosmos, from the big bang to today. understanding their formation from cosmic dawn, their growth, and the emergence of the first, rare quasars in the early universe remains one of our greatest theoretical and observational challenges. hydrodynamic cosmological simulations self-consistently combine the processes of structure formation at cosmological scales with the physics of smaller, galaxy scales. they capture our most realistic understanding of massive black holes and their connection to galaxy formation and have become the primary avenue for theoretical research in this field. the space-based gravitational wave interferometer, lisa, will open up new investigations into the dynamical processes involving massive black holes. multi-messenger astrophysics brings new exciting prospects for tracing the origin, growth and merger history of massive black holes across cosmic ages. | massive black holes in galactic nuclei: theory and simulations |
context. identifying the most likely sources for high-energy neutrino emission has been one of the main topics in high-energy astrophysics ever since the first observation of high-energy neutrinos by the icecube neutrino observatory. active galactic nuclei with relativistic jets, also known as blazars, have been considered to be one of the main candidates because of their ability to accelerate particles to high energies.aims: we study the connection between radio emission and icecube neutrino events using data from the owens valley radio observatory (ovro) and metsähovi radio observatory blazar monitoring programs.methods: we identify sources in our radio monitoring sample that are positionally consistent with icecube high-energy neutrino events. we estimate their mean flux density and variability amplitudes around the neutrino arrival time, and compare these with values from random samples to establish the significance of our results.results: we find radio source associations within our samples with 15 high-energy neutrino events detected by icecube. nearly half of the associated sources are not detected in the γ-ray energies, but their radio variability properties and doppler boosting factors are similar to the γ-ray detected objects in our sample, meaning that they could still be potential neutrino emitters. we find that the number of strongly flaring objects in our statistically complete ovro samples is unlikely to be a random coincidence (at 2σ level).conclusions: based on our results, we conclude that although it is clear that not all neutrino events are associated with strong radio flaring blazars, observations of large-amplitude radio flares in a blazar at the same time as a neutrino event are unlikely to be a random coincidence. flux density data of the associated sources at 15 and 37 ghz are only available at the cds via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/650/a83 | association of icecube neutrinos with radio sources observed at owens valley and metsähovi radio observatories |
x-ray quasi-periodic eruptions (qpes) represent a recently discovered example of extreme x-ray variability associated with supermassive black holes. these are high-amplitude bursts recurring every few hours that are detected in the soft x-ray band from the nuclei of nearby galaxies whose optical spectra lack the broad emission lines typically observed in unobscured active galaxies. the physical origin of this new x-ray variability phenomenon is still unknown and several theoretical models have been presented. however, no attempt has been made so far to account for the varying qpe recurrence time and luminosity in individual sources, nor for the diversity of the qpe phenomenology in the different known erupters. we present a semi-analytical model based on an extreme mass-ratio inspiral (emri) system where the secondary intersects, along its orbit, a rigidly precessing accretion disc surrounding the primary. we assume that qpes result from emission from an adiabatically expanding, initially optically thick gas cloud expelled from the disc plane at each impact. we produced synthetic x-ray light curves, which we then compared with x-ray data from four qpe sources: gsn 069, ero-qpe1, ero-qpe2, and rx j1301.9+2747. our model aptly reproduces the diversity of qpe properties between the considered objects and it is also able to naturally account for the varying qpe amplitudes and recurrence times in individual sources. future implementations will enable us to refine the match with the data and to estimate the system parameters precisely, making additional use of multi-epoch qpe data. we briefly discuss the nature of the secondary object, as well as the possible implications of our findings for the emri population at large. | quasi-periodic eruptions from impacts between the secondary and a rigidly precessing accretion disc in an extreme mass-ratio inspiral system |
using a suite of three large cosmological hydrodynamical simulations, horizon-agn, horizon-noagn (no agn feedback) and horizon-dm (no baryons), we investigate how a typical sub-grid model for agn feedback affects the evolution of the inner density profiles of massive dark matter haloes and galaxies. based on direct object-to-object comparisons, we find that the integrated inner mass and density slope differences between objects formed in these three simulations (hereafter, hagn, hnoagn and hdm) significantly evolve with time. more specifically, at high redshift (z ∼ 5), the mean central density profiles of hagn and hnoagn dark matter haloes tend to be much steeper than their hdm counterparts owing to the rapidly growing baryonic component and ensuing adiabatic contraction. by z ∼ 1.5, these mean halo density profiles in hagn have flattened, pummelled by powerful agn activity ('quasar mode'): the integrated inner mass difference gaps with hnoagn haloes have widened, and those with hdm haloes have narrowed. fast forward 9.5 billion years, down to z = 0, and the trend reverses: hagn halo mean density profiles drift back to a more cusped shape as agn feedback efficiency dwindles ('radio mode'), and the gaps in integrated central mass difference with hnoagn and hdm close and broaden, respectively. on the galaxy side, the story differs noticeably. averaged stellar profile central densities and inner slopes are monotonically reduced by agn activity as a function of cosmic time, resulting in better agreement with local observations. | density profile of dark matter haloes and galaxies in the horizon-agn simulation: the impact of agn feedback |
the detection of starlight from the host galaxies of quasars during the reionization epoch (z > 6) has been elusive, even with deep hubble space telescope observations1,2. the current highest redshift quasar host detected3, at z = 4.5, required the magnifying effect of a foreground lensing galaxy. low-luminosity quasars4-6 from the hyper suprime-cam subaru strategic program (hsc-ssp)7 mitigate the challenge of detecting their underlying, previously undetected host galaxies. here we report rest-frame optical images and spectroscopy of two hsc-ssp quasars at z > 6 with the jwst. using near-infrared camera imaging at 3.6 and 1.5 μm and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of 13 × and 3.4 × 1010 m☉, respectively), compact and disc-like. near-infrared spectroscopy at medium resolution shows stellar absorption lines in the more massive quasar, confirming the detection of the host. velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses (1.4 × 109 and 2.0 × 108 m☉, respectively). their location in the black hole mass-stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the big bang. | detection of stellar light from quasar host galaxies at redshifts above 6 |
the origin of thermal optical and uv emission from stellar tidal disruption flares (tdfs) remains an open question. we present hubble space telescope far-uv (fuv) observations of eight optical/uv-selected tdfs 5-10 yr post-peak. six sources are cleanly detected, showing point-like fuv emission ({10}41.5{--42.5} {erg} {{{s}}}-1) from the centers of their host galaxies. we discover that the light curves of tdfs from low-mass black holes (<106.5 m ⊙) show significant late-time flattening. conversely, fuv light curves from high-mass black hole tdfs are generally consistent with an extrapolation from the early-time light curve. the observed late-time emission cannot be explained by existing models for early-time tdf light curves (i.e., reprocessing or circularization shocks), but is instead consistent with a viscously spreading, unobscured accretion disk. these disk models can only reproduce the observed fuv luminosities, however, if they are assumed to be thermally and viscously stable, in contrast to the simplest predictions of α-disk theory. for one tdf in our sample, we measure an upper limit to the uv luminosity that is significantly lower than expectations from theoretical modeling and an extrapolation of the early-time light curve. this dearth of late-time emission could be due to a disk instability/state change absent in the rest of the sample. the disk models that explain the late-time uv detections solve the tdf “missing energy problem” by radiating a rest-mass energy of ∼0.1 m ⊙ over a period of decades, primarily in extreme uv wavelengths. based on observations made with the nasa/esa hubble space telescope, obtained at the space telescope science institute, which is operated by the association of universities for research in astronomy inc., under nasa contract nas 5-26555. these observations are associated with program go-14255. | late-time uv observations of tidal disruption flares reveal unobscured, compact accretion disks |
we present results from our on-going muse gas flow and wind (megaflow) survey, which consists of 22 quasar lines of sight, each observed with the integral field unit muse and the uves spectrograph at the eso very large telescopes (vlt). the goals of this survey are to study the properties of the circumgalactic medium around z ∼ 1 star-forming galaxies. the absorption-line selected survey consists of 79 strong mg ii absorbers (with rest-frame equivalent width ≳0.3 å) and, currently, 86 associated galaxies within 100 projected kpc of the quasar with stellar masses (m⋆) from 109 to 1011 m⊙. we find that the cool halo gas traced by mg ii is not isotropically distributed around these galaxies from the strong bi-modal distribution in the azimuthal angle of the apparent location of the quasar with respect to the galaxy major axis. this supports a scenario in which outflows are bi-conical in nature and co-exist with a co-planar gaseous structure extending at least up to 60-80 kpc. assuming that absorbers near the minor axis probe outflows, the current megaflow sample allowed us to select 26 galaxy-quasar pairs suitable for studying winds. from this sample, using a simple geometrical model, we find that the outflow velocity only exceeds the escape velocity when m⋆ ≲ 4 × 109 m⊙, implying the cool material is likely to fall back except in the smallest haloes. finally, we find that the mass loading factor η, the ratio between the ejected mass rate and the star formation rate, appears to be roughly constant with respect to the galaxy mass. | muse gas flow and wind (megaflow) - iii. galactic wind properties using background quasars |
motivated by the recent discovery of the near-ubiquity of lyα emission around z ≳ 3 qsos, we performed a systematic study of qso circumgalactic lyα emission at z ≈ 2 utilizing the unique capability of the keck cosmic web imager (kcwi)—a new wide-field, blue sensitive integral field spectrograph. in this paper, we present kcwi observations of a sample of 16 ultraluminous type i qsos at z = 2.1-2.3 with ionizing luminosities of {l}{ν ll}}={10}31.1-32.3 erg s-1 hz-1. we found that 14 out of 16 qsos are associated with lyα nebulae with projected linear sizes larger than 50 physical kpc. among them, four nebulae have enormous lyα emission with a lyα surface brightness (sb) {sb}}lyα }> {10}-17 erg s-1 cm-2 arcsec-2 on the >100 kpc scale, extending beyond the field of view of kcwi. our kcwi observations reveal that most z ≈ 2 qso nebulae have a more irregular morphology compared to those at z ≳ 3. in turn, we measure that the circularly averaged sb at z ≈ 2 is 0.4 dex fainter than the redshift-corrected median sb at z ≳ 3. the lyα sb profile (sblyα ) of qsos at z ≈ 2 can be described by a power law of {sb}}lyα ,z≈ 2.3}=3.7× {10}-17× {(r/40)}-1.8 erg s-1 cm-2 arcsec-2, with a slope similar to that at z ≳ 3. the observed lower redshift-corrected, circularly averaged sb may be mainly due to the lower covering factor of cool gas clouds in massive halos at z ≈ 2. | evolution of the cool gas in the circumgalactic medium of massive halos: a keck cosmic web imager survey of lyα emission around qsos at z ≈ 2 |
quasar emission lines are often shifted from the systemic velocity due to various dynamical and radiative processes in the line-emitting region. the level of these velocity shifts depends both on the line species and on quasar properties. we study velocity shifts for the line peaks (not the centroids) of various narrow and broad quasar emission lines relative to systemic using a sample of 849 quasars from the sloan digital sky survey reverberation mapping (sdss-rm) project. the coadded (from 32 epochs) spectra of individual quasars have sufficient signal-to-noise ratio (s/n) to measure stellar absorption lines to provide reliable systemic velocity estimates, as well as weak narrow emission lines. the large dynamic range in quasar luminosity (∼2 dex) of the sample allowed us to explore potential luminosity dependence of the velocity shifts. we derive average line peak velocity shifts as a function of quasar luminosity for different lines, and quantify their intrinsic scatter. we further quantify how well the peak velocity can be measured as a function of continuum s/n, and demonstrate that there is no systematic bias in the velocity measurements when s/n is degraded to as low as ∼3 per sdss pixel (∼ 69 {km} {{{s}}}-1). based on the observed line shifts, we provide empirical guidelines on redshift estimation from [o ii] λ 3727, [o iii] λ 5007, [ne v] λ 3426, mg ii, c iii], he ii λ 1640, broad hβ, c iv, and si iv, which are calibrated to provide unbiased systemic redshifts in the mean, but with increasing intrinsic uncertainties of 46, 56, 119, 205, 233, 242, 400, 415, and 477 {km} {{{s}}}-1, in addition to the measurement uncertainties. these results demonstrate the infeasibility of measuring quasar redshifts to better than ∼ 200 {km} {{{s}}}-1 with only broad lines. | the sloan digital sky survey reverberation mapping project: velocity shifts of quasar emission lines |
as part of the sloan digital sky survey (sdss) iv the extended baryon oscillation spectroscopic survey (eboss) will improve measurements of the cosmological distance scale by applying the baryon acoustic oscillation (bao) method to quasar samples. eboss will adopt two approaches to target quasars over 7500 deg2. first, a “core” quasar sample will combine the optical selection in ugriz using a likelihood-based routine called xdqsoz, with a mid-ir-optical color cut. eboss core selection (to g < 22 or r < 22) should return ∼70 deg-2 quasars at redshifts 0.9 < z < 2.2 and ∼7 deg-2z > 2.1 quasars. second, a selection based on variability in multi-epoch imaging from the palomar transient factory should recover an additional ∼3-4 deg-2z > 2.1 quasars to g < 22.5. a linear model of how imaging systematics affect target density recovers the angular distribution of eboss core quasars over 96.7% (76.7%) of the sdss north (south) galactic cap area. the eboss core quasar sample should thus be sufficiently dense and homogeneous over 0.9 < z < 2.2 to yield the first few-percent-level bao constraint near \bar{z}∼ 1.5.eboss quasars at z > 2.1 will be used to improve bao measurements in the lyα forest. beyond its key cosmological goals, eboss should be the next-generation quasar survey, comprising >500,000 new quasars and >500,000 uniformly selected spectroscopically confirmed 0.9 < z < 2.2 quasars. at the conclusion of eboss, the sdss will have provided unique spectra for more than 800,000 quasars. | the sdss-iv extended baryon oscillation spectroscopic survey: quasar target selection |
we study quasar proximity zones in the redshift range 5.77≤slant z≤slant 6.54 by homogeneously analyzing 34 medium-resolution spectra, encompassing both archival and newly obtained data, and exploiting recently updated systemic redshift and magnitude measurements. whereas previous studies found strong evolution of proximity zone sizes with redshift and argued that this provides evidence for a rapidly evolving intergalactic medium (igm) neutral fraction during reionization, we measure a much shallower trend \propto {(1+z)}-1.44. we compare our measured proximity zone sizes to predictions from hydrodynamical simulations post-processed with one-dimensional radiative transfer and find good agreement between observations and theory, irrespective of the ionization state of the ambient igm. this insensitivity to igm ionization state has been previously noted, and results from the fact that the definition of proximity zone size as the first drop of the smoothed quasar spectrum below the 10% flux transmission level probes locations where the ionizing radiation from the quasar is an order of magnitude larger than the expected ultraviolet ionizing background that sets the neutral fraction of the igm. our analysis also uncovered three objects with exceptionally small proximity zones (two have {r}p< 1 proper mpc), which constitute outliers from the observed distribution and are challenging to explain with our radiative transfer simulations. we consider various explanations for their origin, such as strong absorption line systems associated with the quasar or patchy reionization, but find that the most compelling scenario is that these quasars have been shining for ≲105 years. | implications of z ∼ 6 quasar proximity zones for the epoch of reionization and quasar lifetimes |
despite their factor of ∼108 difference in black hole mass, several lines of evidence suggest possible similarities between black hole accretion flows in active galactic nuclei (agn) and galactic x-ray binaries. however, it is still unclear whether the geometry of the disk-corona system in x-ray binaries directly scales up to agn and whether this analogy still holds in different accretion states. we test this agn/x-ray binary analogy by comparing the observed correlations between the uv-to-x-ray spectral index (α ox) and eddington ratio in agn to those predicted from observations of x-ray binary outbursts. this approach probes the geometry of their disk-corona systems as they transition between different accretion states. we use new chandra x-ray and ground-based rest-uv observations of faded “changing-look” quasars to extend this comparison to lower eddington ratios of <10-2, where observations of x-ray binaries predict a softening of α ox in agn. we find that the observed correlations between the α ox and eddington ratio of agn displays a remarkable similarity to accretion state transitions in prototypical x-ray binary outbursts, including an inversion of this correlation at a critical eddington ratio of ∼10-2. our results suggest that the structures of black hole accretion flows directly scale across a factor of ∼108 in black hole mass and across different accretion states, enabling us to apply theoretical models of x-ray binaries to explain agn phenomenology. | the analogous structure of accretion flows in supermassive and stellar mass black holes: new insights from faded changing-look quasars |
in a companion paper, we reported the self-consistent formation of quasar accretion disks with inflow rates $\sim 10\,{\rm m_{\odot}\,yr^{-1}}$ down to <300 schwarzschild radii from cosmological radiation-magneto-thermochemical-hydrodynamical galaxy and star formation simulations. we see the formation of a well-defined, steady-state accretion disk which is stable against star formation at sub-pc scales. the disks are optically thick, with radiative cooling balancing accretion, but with properties that are distinct from those assumed in most previous accretion disk models. the pressure is strongly dominated by (primarily toroidal) magnetic fields, with a plasma $\beta \sim 10^{-4}$ even in the disk midplane. they are qualitatively distinct from magnetically elevated or arrested disks. the disks are strongly turbulent, with trans-alfvenic and highly super-sonic turbulence, and balance this via a cooling time that is short compared to the disk dynamical time, and can sustain highly super-eddington accretion rates. their surface and 3d densities at $\sim 10^{3}-10^{5}$ gravitational radii are much lower than in a shakura-sunyaev disk, with important implications for their thermo-chemistry and stability. we show how the magnetic field strengths and geometries arise from rapid advection of flux with the inflow from much weaker galaxy-scale fields in these 'flux-frozen' disks, and how this stabilizes the disk and gives rise to efficient torques. re-simulating without magnetic fields produces catastrophic fragmentation with a vastly smaller, lower-$\dot{m}$ shakura-sunyaev-like disk. | forge'd in fire ii: the formation of magnetically-dominated quasar accretion disks from cosmological initial conditions |
strongly lensed quasar systems with time delay measurements provide “time delay distances,” which are a combination of three angular diameter distances and serve as powerful tools to determine the hubble constant h 0. however, current results often rely on the assumption of the λcdm model. here we use a model-independent method based on gaussian process to directly constrain the value of h 0. by using gaussian process regression, we can generate posterior samples of unanchored supernova distances independent of any cosmological model and anchor them with strong lens systems. the combination of a supernova sample with large statistics but no sensitivity to h 0 with a strong lens sample with small statistics but h 0 sensitivity gives a precise h 0 measurement without the assumption of any cosmological model. we use four well-analyzed lensing systems from the state-of-art lensing program h0licow and the pantheon supernova compilation in our analysis. assuming the universe is flat, we derive the constraint h 0 = 72.2 ± 2.1 km s-1 mpc-1, a precision of 2.9%. allowing for cosmic curvature with a prior of ω k= [-0.2, 0.2], the constraint becomes {h}0={73.0}-3.0+2.8 {km} {{{s}}}-1 {mpc}}-1. | a model-independent determination of the hubble constant from lensed quasars and supernovae using gaussian process regression |
in 2019 july, the icecube experiment detected a high-energy neutrino from the direction of the powerful blazar pks 1502+106. we perform multiwavelength and multimessenger modeling of this source, using a fully selfconsistent one-zone model that includes the contribution of external radiation fields typical of flat-spectrum radio quasars. we identify three different activity states of the blazar: one quiescent state and two flaring states with hard and soft gamma-ray spectra. we find two hadronic models that can describe the multiwavelength emission during all three states: a leptohadronic model with a contribution from photohadronic processes to x-rays and gamma-rays, and a proton synchrotron model, where the emission from kev to 10 gev comes from proton synchrotron radiation. both models predict a substantial neutrino flux that is correlated with the gamma-ray and soft x-ray fluxes. our results are compatible with the detection of a neutrino during the quiescent state, based on event rate statistics. we conclude that the soft x-ray spectra observed during bright flares strongly suggest a hadronic contribution, which can be interpreted as additional evidence for cosmic-ray acceleration in the source independently of neutrino observations. we find that more arguments can be made in favor of the leptohadronic model vis-a-vis the proton synchrotron scenario, such as a lower energetic demand during the quiescent state. however, the same leptohadronic model would be disfavored for flaring states of pks 1502+106 if no icecube events were found from the direction of the source before 2010, which would require an archival search. | multiwavelength and neutrino emission from blazar pks 1502 + 106 |
in this work, we establish and test methods for implementing dynamical friction (df) for massive black hole pairs that form in large volume cosmological hydrodynamical simulations that include galaxy formation and black hole growth. we verify our models and parameters both for individual black hole dynamics and for the black hole population in cosmological volumes. using our model of df from collisionless particles, black holes can effectively sink close to the galaxy centre, provided that the black hole's dynamical mass is at least twice that of the lowest mass resolution particles in the simulation. gas drag also plays a role in assisting the black holes' orbital decay, but it is typically less effective than that from collisionless particles, especially after the first billion years of the black hole's evolution. df from gas becomes less than $1{{\ \rm per\ cent}}$ of df from collisionless particles for bh masses >107 m⊙. using our best df model, we calculate the merger rate down to z = 1.1 using an lbox = 35 mpc h-1 simulation box. we predict ~2 mergers per year for z > 1.1 peaking at z ~ 2. these merger rates are within the range obtained in previous work using similar resolution hydrodynamical simulations. we show that the rate is enhanced by factor of ~2 when df is taken into account in the simulations compared to the no-df run. this is due to ${\gt}40{{\ \rm per\ cent}}$ more black holes reaching the centre of their host halo when df is added. | dynamical friction modelling of massive black holes in cosmological simulations and effects on merger rate predictions |
we report the results of a multiband observing campaign on the famous blazar 3c 279 conducted during a phase of increased activity from 2013 december to 2014 april, including first observations of it with nustar. the γ-ray emission of the source measured by fermi-lat showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the fermi mission, with f(e\gt 100 {mev}) of 10-5 photons cm-2 s-1, and with a flux-doubling time scale as short as 2 hr. the γ-ray spectrum during one of the flares was very hard, with an index of {{{γ }}}γ =1.7+/- 0.1, which is rarely seen in flat-spectrum radio quasars. the lack of concurrent optical variability implies a very high compton dominance parameter {l}γ /{l}{syn}\gt 300. two 1 day nustar observations with accompanying swift pointings were separated by 2 weeks, probing different levels of source activity. while the 0.5-70 kev x-ray spectrum obtained during the first pointing, and fitted jointly with swift-xrt is well-described by a simple power law, the second joint observation showed an unusual spectral structure: the spectrum softens by {{δ }}{{{γ }}}{{x}}≃ 0.4 at ∼4 kev. modeling the broadband spectral energy distribution during this flare with the standard synchrotron plus inverse-compton model requires: (1) the location of the γ-ray emitting region is comparable with the broad-line region radius, (2) a very hard electron energy distribution index p≃ 1, (3) total jet power significantly exceeding the accretion-disk luminosity {l}j/{l}d≳ 10, and (4) extremely low jet magnetization with {l}b/{l}j≲ {10}-4. we also find that single-zone models that match the observed γ-ray and optical spectra cannot satisfactorily explain the production of x-ray emission. | rapid variability of blazar 3c 279 during flaring states in 2013-2014 with joint fermi-lat, nustar, swift, and ground-based multiwavelength observations |
short-lived intermittent phases of super-critical (super-eddington) growth, coupled with star formation via positive feedback, may account for early growth of massive black holes (mbh) and coevolution with their host spheroids. we estimate the possible growth rates and duty cycles of these episodes, both assuming slim accretion disk solutions and adopting the results of recent numerical simulations. the angular momentum of gas joining the accretion disk determines the length of the accretion episodes and the final mass that an mbh can reach. the latter can be related to the gas velocity dispersion and, in galaxies with low-angular momentum gas, the mbh can reach a higher mass. when the host galaxy is able to sustain inflow rates at 1-100 {{m}⊙ } y{{r}-1}, replenishing and circulation lead to a sequence of short (∼ {{10}4}-{{10}7} yr), heavily obscured accretion episodes that increase the growth rates, with respect to an eddington-limited case, by several orders of magnitude. our model predicts that the ratio of the mbh accretion rate-to-star formation rate is 10-2 or higher, leading, at early epochs, to a ratio of mbh-to-stellar mass that is higher than the “canonical” value of ∼ {{10}-3}, which is in agreement with current observations. our model makes specific predictions that long-lived super-critical accretion occurs only in galaxies with copious low-angular momentum gas, and, in this case, the mbh is more massive at a fixed velocity dispersion. | the case for supercritical accretion onto massive black holes at high redshift |
we use updated type ia pantheon +supernova , baryon acoustic oscillation, and hubble parameter (now also accounting for correlations) data, as well as new reverberation-measured c iv quasar data, and quasar angular size, h ii starburst galaxy, reverberation-measured mg ii quasar, and amati-correlated gamma-ray burst data to constrain cosmological parameters. we show that these datasets result in mutually consistent constraints and jointly use them to constrain cosmological parameters in six different spatially flat and nonflat cosmological models. our analysis provides summary model-independent determinations of two key cosmological parameters: the hubble constant, h0=69.8 ±1.3 km s-1 mpc-1 , and the current nonrelativistic matter density parameter, ωm 0=0.288 ±0.017 . our summary error bars are 2.4 and 2.3 times those obtained using the flat cosmological constant cold dark matter (λ cdm ) model and planck tt ,te ,ee +lowe +lensing cosmic microwave background (cmb) anisotropy data. our h0 value is very consistent with that from the local expansion rate based on the tip of the red giant branch and type ia supernova (sn ia) data, is 2 σ lower than that from the local expansion rate based on cepheid and sn ia data, and is 2 σ higher than that in the flat λ cdm model based on planck tt ,te ,ee +lowe +lensing cmb data. our data compilation shows at most mild evidence for nonflat spatial hypersurfaces, but more significant evidence for dark energy dynamics, 2 σ or larger in the spatially flat dynamical dark energy models we study. | h0=69.8 ±1.3 km s-1 mpc-1 , ωm 0=0.288 ±0.017 , and other constraints from lower-redshift, non-cmb, expansion-rate data |
we use cosmological hydrodynamical simulations to examine the physical properties of the gas in the circumgalactic media (cgm) of star-forming galaxies as a function of angular orientation. we utilize tng50 of the illustristng project, as well as the eagle simulation to show that observable properties of cgm gas correlate with azimuthal angle, defined as the galiocentric angle with respect to the central galaxy. both simulations are in remarkable agreement in predicting a strong modulation of flow rate direction with azimuthal angle: inflow is more substantial along the galaxy major axis, while outflow is strongest along the minor axis. the absolute rates are noticeably larger for higher ( $\log {(m_\star / \rm {m}_\odot)} \sim 10.5$ ) stellar mass galaxies, up to an order of magnitude compared to $\dot{m} \lesssim 1$ m⊙ yr-1 sr-1 for $\log {(m_\star / \rm {m}_\odot)}\sim 9.5$ objects. notwithstanding the different numerical and physical models, both tng50 and eagle predict that the average metallicity of the cgm is higher along the minor versus major axes of galaxies. the angular signal is robust across a wide range of galaxy stellar mass $8.5 \lt \log {(m_\star / \rm {m}_\odot)} \lt 10.5$ at z < 1. this azimuthal dependence is particularly clear at larger impact parameters b ≥ 100 kpc. our results present a global picture, whereby despite the numerous mixing processes, there is a clear angular dependence of the cgm metallicity. we make forecasts for future large survey programmes that will be able to compare against these expectations. indeed, characterizing the kinematics, spatial distribution and metal content of cgm gas is key to a full understanding of the exchange of mass, metals, and energy between galaxies and their surrounding environments. | predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium |
quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to overgrow and producing the red colors of ellipticals. on the other hand, some models are also requiring "positive" active galactic nucleus feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. however, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively driven winds are available. here we present sinfoni near infrared integral field spectroscopy of xid2028, an obscured, radio-quiet z = 1.59 qso detected in the xmm-cosmos survey, in which we clearly resolve a fast (1500 km s-1) and extended (up to 13 kpc from the black hole) outflow in the [o iii] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. the narrow component of hα emission and the rest frame u-band flux from hubble space telescope/advanced camera for surveys imaging enable to map the current star formation in the host galaxy: both tracers independently show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. the outflow is therefore removing the gas from the host galaxy ("negative feedback"), but also triggering star formation by outflow induced pressure at the edges ("positive feedback"). xid2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work. | blowin\' in the wind: both "negative" and "positive" feedback in an obscured high-z quasar |
a quasar catalogue is presented with a total of 510 764 objects including 424 748 type 1 qsos and 26 623 type 1 agn complete from the literature to 2015 january 25. also included are 25015 high-confidence sdss-based photometric quasars with radio/x-ray associations, 1595 bl lac objects, and 32783 type 2 objects. each object is displayed with arcsecond-accurate astrometry, red and blue photometry, redshift, citations, and radio and x-ray associations where present. also, 114 new spectroscopically confirmed quasars are presented. | the half million quasars (hmq) catalogue |
we use the 2015 risaliti and lusso compilation of 808 x-ray and uv flux measurements of quasars (qsos) in the redshift range 0.061 ≤ z ≤ 6.28, alone and in conjunction with baryon acoustic oscillation (bao) and hubble parameter [h(z)] measurements, to constrain cosmological parameters in six cosmological models. the qso data constraints are significantly weaker than, but consistent with, those from the h(z) + bao data. a joint analysis of the qso + h(z) + bao data is consistent with the current standard model, spatially flat λ cold dark matter, but mildly favours closed spatial hypersurfaces and dynamical dark energy. | quasar x-ray and uv flux, baryon acoustic oscillation, and hubble parameter measurement constraints on cosmological model parameters |
we present constraints on local primordial non-gaussianity (png), parametrized through fnlloc, using the sloan digital sky survey iv extended baryon oscillation spectroscopic survey data release 14 quasar sample. we measure and analyze the anisotropic clustering of the quasars in fourier space, testing for the scale-dependent bias introduced by primordial non-gaussianity on large scales. we derive and employ a power spectrum estimator using optimal weights that account for the redshift evolution of the png signal. we find constraints of -51<fnlloc<21 at 95% confidence level. these are among the tightest constraints from large scale structure (lss) data. our redshift weighting improves the error bar by 15% in comparison to the unweighted case. if quasars have lower response to png, the constraint degrades to -81<fnlloc<26, with a 40% improvement over the standard approach. we forecast that the full eboss dataset could reach σfnllocsimeq 5-8 using optimal methods and full range of scales. | redshift-weighted constraints on primordial non-gaussianity from the clustering of the eboss dr14 quasars in fourier space |
observational studies of collimation in jets in active galactic nuclei (agn) are a key to understanding their formation and acceleration processes. we have performed an automated search for jet shape transitions in a sample of 367 agn using vlba data at 15 and 1.4 ghz. this search has found 10 out of 29 nearby jets at redshifts z < 0.07 with a transition from a parabolic to conical shape, while the full analysed sample is dominated by distant agn with a typical z ≈ 1. the ten agn are ugc 00773, ngc 1052, 3c 111, 3c 120, txs 0815-094, mrk 180, pks 1514+00, ngc 6251, 3c 371, and bl lac. we conclude that the geometry transition may be a common effect in agn jets. it can be observed only when sufficient linear resolution is obtained. supplementing these results with previously reported shape breaks in the nearby agn 1h 0323+342 and m87, we estimate that the break occurs at 105-106 gravitational radii from the nucleus. we suggest that the jet shape transition happens when the bulk plasma kinetic energy flux becomes equal to the poynting energy flux, while the ambient medium pressure is assumed to be governed by bondi accretion. in general, the break point may not coincide with the bondi radius. the observational data support our model predictions on the jet acceleration and properties of the break point. | a transition from parabolic to conical shape as a common effect in nearby agn jets |
in this work we investigate the properties of the sources that reionized the intergalactic medium (igm) in the high-redshift universe. using a semi-analytical model aimed at reproducing galaxies and black holes in the first ∼1.5 gyr of the universe, we revisit the relative role of star formation and black hole accretion in producing ionizing photons that can escape into the igm. both star formation and black hole accretion are regulated by supernova feedback, resulting in black hole accretion being stunted in low-mass haloes. we explore a wide range of combinations for the escape fraction of ionizing photons (redshift-dependent, constant, and scaling with stellar mass) from both star formation ( $\langle f_{\rm esc}^{\rm sf} \rangle$ ) and agn ( $f_{\rm esc}^{\rm bh}$ ) to find: (i) the ionizing budget is dominated by stellar radiation from low stellar mass ( $m_*\lt 10^9 \, {\rm \rm m_\odot }$ ) galaxies at z > 6 with the agn contribution (driven by $m_{bh}\gt 10^6 \, {\rm \rm m_\odot }$ black holes in $m_* \gtrsim 10^9\, {\rm \rm m_\odot }$ galaxies) dominating at lower redshifts; (ii) agn only contribute $10-25{{\ \rm per\ cent}}$ to the cumulative ionizing emissivity by z = 4 for the models that match the observed reionization constraints; (iii) if the stellar mass dependence of $\langle f_{\rm esc}^{\rm sf} \rangle$ is shallower than $f_{\rm esc}^{\rm bh}$ , at z < 7 a transition stellar mass exists above which agn dominate the escaping ionizing photon production rate; (iv) the transition stellar mass decreases with decreasing redshift. while agn dominate the escaping emissivity above the knee of the stellar mass function at z ∼ 6.8, they take-over at stellar masses that are a tenth of the knee mass by z = 4. | reionization with galaxies and active galactic nuclei |
context. gaia-crf3 is the celestial reference frame for positions and proper motions in the third release of data from the gaia mission, gaia dr3 (and for the early third release, gaia edr3, which contains identical astrometric results). the reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (e)dr3 catalogue.aims: we describe the construction of gaia-crf3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality.methods: compact extragalactic sources in gaia dr3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (qso) and active galactic nuclei (agn), followed by astrometric filtering designed to remove stellar contaminants. selecting a clean sample was favoured over including a higher number of extragalactic sources. for the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the international celestial reference frame (icrf3).results: gaia-crf3 comprises about 1.6 million qso-like sources, of which 1.2 million have five-parameter astrometric solutions in gaia dr3 and 0.4 million have six-parameter solutions. the sources span the magnitude range g = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. the proper motions show systematic errors on the level of 12 µas yr-1 on angular scales greater than 15 deg. for the 3142 optical counterparts of icrf3 sources in the s/x frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. we outline the future of gaia-crf in the next gaia data releases. appendices give further details on the external catalogues used, how to extract information about the gaia-crf3 sources, potential (galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution. | gaia early data release 3. the celestial reference frame (gaia-crf3) |
we present the first rest-frame optical spectrum of a high-redshift quasar observed with jwst/nircam in wide field slitless mode. the observed quasar, j0100+2802, is the most luminous quasar known at z > 6. we measure the mass of the central supermassive black hole (smbh) by means of the rest-frame optical h β emission line, and find consistent mass measurements of the quasar's smbh of m • ≈ 1010 m ☉ when compared to the estimates based on the properties of rest-frame uv emission lines c iv and mg ii, which are accessible from ground-based observatories. to this end, we also present a newly reduced rest-frame uv spectrum of the quasar observed with x-shooter/very large telescope (vlt) and fire/magellan for a total of 16.8 hr. we readdress the question whether this ultraluminous quasar could be effected by strong gravitational lensing making use of the diffraction limited nircam images in three different wide band filters (f115w, f200w, f356w), which improves the achieved spatial resolution compared to previous images taken with the hubble space telescope by a factor of 2. we do not find any evidence for a foreground deflecting galaxy, nor for multiple images of the quasar, and determine the probability for magnification due to strong gravitational lensing with image separations below the diffraction limit of δθ ≲ 0.″05 to be ≲2.2 × 10-3. our observations therefore confirm that this quasar hosts a 10 billion solar mass black hole less than 1 gyr after the big bang, which is challenging to explain with current black hole formation models. | eiger. iii. jwst/nircam observations of the ultraluminous high-redshift quasar j0100+2802 |
we present the first results from romulusc, the highest resolution cosmological hydrodynamic simulation of a galaxy cluster run to date. romulusc, a zoom-in simulation of a halo with z = 0 mass 1014 m⊙, is run with the same sub-grid physics and resolution as romulus25. with unprecedented mass and spatial resolution, romulusc represents a unique opportunity to study the evolution of galaxies in dense environments down to dwarf masses. we demonstrate that romulusc results in an intracluster medium consistent with observations. the star formation history and stellar mass of the brightest cluster galaxy (bcg) is consistent with observations and abundance matching results, indicating that our sub-grid models, optimized only to reproduce observations of field dwarf and milky way mass galaxies, are able to produce reasonable galaxy masses and star formation histories in much higher mass systems. feedback from supermassive black holes (smbhs) regulates star formation by driving large-scale, collimated outflows that coexist with a low-entropy core. we find that non-bcg cluster member galaxies are substantially quenched compared to the field down to dwarf galaxy masses and, at low masses, quenching is seen to have no dependence on mass or distance from the cluster centre. this enhanced quenched population extends beyond r200 and is in place at high redshift. similarly, we predict that an smbh activity is significantly suppressed within clusters outside of the bcg, but show how the effect could be lost when only focusing on the brightest active galactic nucleus in the most massive galaxies. | introducing romulusc: a cosmological simulation of a galaxy cluster with an unprecedented resolution |
supermassive primordial stars forming in atomically cooled haloes at z ∼ 15-20 are currently thought to be the progenitors of the earliest quasars in the universe. in this picture, the star evolves under accretion rates of 0.1-1 m⊙ yr-1 until the general relativistic instability triggers its collapse to a black hole at masses of ∼105 m⊙. however, the ability of the accretion flow to sustain such high rates depends crucially on the photospheric properties of the accreting star, because its ionizing radiation could reduce or even halt accretion. here we present new models of supermassive population iii protostars accreting at rates 0.001-10 m⊙ yr-1, computed with the geneva stellar evolution code including general relativistic corrections to the internal structure. we compute for the first time evolutionary tracks in the mass range m > 105 m⊙. we use the polytropic stability criterion to estimate the mass at which the collapse occurs, which has been shown to give a lower limit of the actual mass at collapse in recent hydrodynamic simulations. we find that at accretion rates higher than 0.01 m⊙ yr-1, the stars evolve as red, cool supergiants with surface temperatures below 104 k towards masses >105 m⊙. moreover, even with the lower rates 0.001 m_{⊙} yr{^{-1}}<\dot{m}< 0.01 m⊙ yr-1, the surface temperature is substantially reduced from 105 to 104 k for m ≳ 600 m⊙. compared to previous studies, our results extend the range of masses and accretion rates at which the ionizing feedback remains weak, reinforcing the case for direct collapse as the origin of the first quasars. we provide numerical tables for the surface properties of our models. | the evolution of supermassive population iii stars |
we use the large boss dr9 sample of quasar spectra to constrain two cases of non-thermal dark matter models: cold-plus-warm dark matter (c+wdm) where the warm component is a thermal relic, and sterile neutrinos resonantly produced in the presence of a lepton asymmetry (rpsn). we establish constraints on the thermal relic mass mx and its relative abundance fwdm=ωwdm/ωdm using a suite of cosmological hydrodynamical simulations in 28 c+wdm configurations. we find that the 3σ bounds in the mx - fwdm parameter space approximately follow fwdm ~ 0.35 (kev/mx)-1.37 from boss data alone. we also establish constraints on sterile neutrino mass and mixing angle by further producing the non-linear flux power spectrum of 8 rpsn models, where the input linear power spectrum is computed directly from the particles distribution functions. we find values of lepton asymmetries for which sterile neutrinos as light as ~ 6.5 kev (resp. 3.5 kev) are consistent with boss data at the 2σ (resp. 3σ) level. these limits tighten by close to a factor of 2 for values of lepton asymmetries departing from those yielding the coolest distribution functions. our lyman-α forest bounds can be additionally strengthened if we include higher-resolution data from xq-100, hires and mike that allow us to probe smaller scales. at these scales, the measured flux power spectrum exhibits a suppression that can be due to doppler broadening, igm pressure smoothing or free-streaming of wdm particles. in order to distinguish between these mechanisms, thermal history at redshifts z >= 5 should be determined. in the current work, we show that if one extrapolates temperatures from lower redshifts via broken power laws in t0 and γ, then our 3σ c+wdm {bounds strengthen to fwdm ~ 0.20 (kev/mx)-1.37, and the lightest resonantly-produced sterile neutrinos consistent with our extended data set have masses of ~ 7.0 kev at the 3σ level. in particular, using dedicated hydrodynamical simulations, we show that} a hypothetical 7 kev sterile neutrino produced in a lepton asymmetry of script l = | nνe - nbar nue | / s = 8 × 10-6 is consistent at 1.9 σ (resp. 3.1 σ) with boss (resp. boss + higher-resolution) data, {for the thermal history models tested in this work. more information about the state of the igm at redshifts 5-6 will allow one to conclude whether the small-scale suppression of the flux power spectrum is due to such sterile neutrino or to thermal effects. | constraints from ly-α forests on non-thermal dark matter including resonantly-produced sterile neutrinos |
we present a new, all-sky quasar catalog, quaia, that samples the largest comoving volume and has the cleanest selection function of any existing spectroscopic quasar sample. the catalog draws on the 6,649,162 quasar candidates identified by the gaia mission that have redshift estimates from the space observatory's low-resolution bp/rp spectra. this initial sample is highly homogeneous and complete, but has low purity, and 18% of even the bright ($g<20.0$) confirmed quasars have discrepant redshift estimates ($|\delta z/(1+z)| > 0.2$) compared to those from the sloan digital sky survey (sdss). in this work, we combine the gaia candidates with unwise infrared data (based on the wide-field infrared survey explorer survey) to construct a catalog useful for cosmological and astrophysical quasar studies. we apply cuts based on proper motions and gaia and unwise colors, reducing the number of contaminants by $\sim$4$\times$. we improve the redshifts by training a $k$-nearest neighbors model on colors and gaia redshift estimates and using sdss redshift labels, and achieve redshift estimates on the $g<20.0$ sample with only 6% (10%) catastrophic errors with $|\delta z/(1+z)| > 0.2$ ($0.1$), a reduction of $\sim$3$\times$ ($\sim$2$\times$) compared to the gaia redshifts. the final catalog has 1,295,502 quasars with a $g<20.5$, and 755,850 candidates in an even cleaner $g<20.0$ sample. we also construct a rigorous all-sky selection function model for the catalog. we compare quaia to existing quasar catalogs, in particular showing that its large effective volume makes it a highly competitive sample for cosmological large-scale structure analyses. the catalog is publicly available at https://doi.org/10.5281/zenodo.8060755. | quaia, the gaia-unwise quasar catalog: an all-sky spectroscopic quasar sample |
we have conducted a search for new strong gravitational lensing systems in the dark energy spectroscopic instrument legacy imaging surveys' data release 8. we use deep residual neural networks, building on previous work presented by huang et al. these surveys together cover approximately one-third of the sky visible from the northern hemisphere, reaching a z-band ab magnitude of ∼22.5. we compile a training sample that consists of known lensing systems as well as non-lenses in the legacy surveys and the dark energy survey. after applying our trained neural networks to the survey data, we visually inspect and rank images with probabilities above a threshold. here we present 1210 new strong lens candidates. | discovering new strong gravitational lenses in the desi legacy imaging surveys |
the broad line region (blr) in active galactic nuclei (agns) is composed of dense gas (∼1011 cm-3) on sub-pc scale, which absorbs about 30 per cent of the ionizing continuum. the outer size of the blr is likely set by dust sublimation, and its density by the incident radiation pressure compression (rpc). but, what is the origin of this gas, and what sets its covering factor (cf)? czerny & hryniewicz (2011) suggested that the blr is a failed dusty wind from the outer accretion disc. we explore the expected dust properties, and the implied blr structure. we find that graphite grains sublimate only at t ≃ 2000 k at the predicted density of ∼1011 cm-3, and therefore large graphite grains (≥0.3 μm) survive down to the observed size of the blr, rblr. the dust opacity in the accretion disc atmosphere is ∼50 times larger than previously assumed, and leads to an inflated torus-like structure, with a predicted peak height at rblr. the illuminated surface of this torus-like structure is a natural place for the blr. the blr cf is mostly set by the gas metallicity, the radiative accretion efficiency, a dynamic configuration and ablation by the incident optical-uv continuum. this model predicts that the blr should extend inwards of rblr to the disc radius where the surface temperature is ≃2000 k, which occurs at rin ≃ 0.18rblr. the value of rin can be tested by reverberation mapping of the higher ionization lines, predicted by rpc to peak well inside rblr. the dust inflated disc scenario can also be tested based on the predicted response of rblr and the cf to changes in the agn luminosity and accretion rate. | dust inflated accretion disc as the origin of the broad line region in active galactic nuclei |
we introduce a new set of large-scale, high-resolution hydrodynamical simulations of the intergalactic medium: the sherwood simulation suite. these are performed in volumes of 103-1603h-3 comoving mpc3, span almost four orders of magnitude in mass resolution with up to 17.2 billion particles, and employ a variety of physics variations including warm dark matter and galactic outflows. we undertake a detailed comparison of the simulations to high-resolution, high signal-to-noise observations of the ly α forest over the redshift range 2 ≤ z ≤ 5. the simulations are in very good agreement with the observational data, lending further support to the paradigm that the ly α forest is a natural consequence of the web-like distribution of matter arising in λcold dark matter cosmological models. only a small number of minor discrepancies remain with respect to the observational data. saturated ly α absorption lines with column densities n_{h i}>10^{14.5} cm^{-2} at 2 < z < 2.5 are underpredicted in the models. an uncertain correction for continuum placement bias is required to match the distribution and power spectrum of the transmitted flux, particularly at z > 4. finally, the temperature of intergalactic gas in the simulations may be slightly too low at z = 2.7 and a flatter temperature-density relation is required at z = 2.4, consistent with the expected effects of non-equilibrium ionization during he ii reionization. | the sherwood simulation suite: overview and data comparisons with the lyman α forest at redshifts 2 ≤ z ≤ 5 |
we present reverberation-mapping (rm) lags and black hole mass measurements using the c iv λ1549 broad emission line from a sample of 348 quasars monitored as a part of the sloan digital sky survey rm project. our data span four years of spectroscopic and photometric monitoring for a total baseline of 1300 days, allowing us to measure lags up to ∼750 days in the observed frame (this corresponds to a rest-frame lag of ∼300 days in a quasar at z = 1.5 and ∼190 days at z = 3). we report significant time delays between the continuum and the c iv λ1549 emission line in 48 quasars, with an estimated false-positive detection rate of 10%. our analysis of marginal lag measurements indicates that there are on the order of ∼100 additional lags that should be recoverable by adding more years of data from the program. we use our measurements to calculate black hole masses and fit an updated c iv radius-luminosity relationship. our results significantly increase the sample of quasars with c iv rm results, with the quasars spanning two orders of magnitude in luminosity toward the high-luminosity end of the c iv radius-luminosity relation. in addition, these quasars are located at some of the highest redshifts (z ≈ 1.4-2.8) of quasars with black hole masses measured with rm. this work constitutes the first large sample of c iv rm measurements in more than a dozen quasars, demonstrating the utility of multiobject rm campaigns. | the sloan digital sky survey reverberation mapping project: initial c iv lag results from four years of data |
negative feedback from active galactic nuclei (agn) is the leading mechanism for the quenching of massive galaxies in the vast majority of modern galaxy evolution models. however, direct observational evidence that agn feedback causes quenching on a population scale is lacking. studies have shown that luminous agn are preferentially located in gas-rich and star-forming galaxies, an observation that has sometimes been suggested to be in tension with a negative agn feedback picture. we investigate three of the current cosmological simulations (illustristng, eagle, and simba) along with post-processed models for molecular hydrogen gas masses and perform similar tests to those used by observers. we find that the simulations predict: (i) no strong negative trends between lbol and $f_{\mathrm{ h}_2}$ or specific star formation rate (ssfr); (ii) both high-luminosity ($l_{\rm {bol}} \ge 10^{44}\rm {\, erg\, s^{-1}}$) and high eddington ratio (λedd $\ge 1{{\ \rm per\ cent}}$) agn are preferentially located in galaxies with high molecular gas fractions and ssfr; and (iii) that the gas-depleted and quenched fractions of agn host galaxies are lower than a control sample of non-active galaxies. these three findings are in qualitative agreement with observational samples at z = 0 and z = 2 and show that such results are not in tension with the presence of strong agn feedback, which all simulations we employ require to produce realistic massive galaxies. however, we also find quantifiable differences between predictions from the simulations, which could allow us to observationally test the different subgrid feedback models. | cosmological simulations predict that agn preferentially live in gas-rich, star-forming galaxies despite effective feedback |
we present the to-date largest parameter space exploration of binaries in circumbinary discs (cbds), deriving orbital evolution prescriptions for eccentric, unequal mass binaries from our suite of hydrodynamic simulations. in all cases, binary eccentricities evolve towards steady state values that increase with mass ratio, and saturate at an equilibrium eccentricity eb,eq ~ 0.5 in the large mass ratio regime, in line with resonant theory. for binaries accreting at their combined eddington limit, a steady state eccentricity can be achieved within a few megayears. once at their steady state eccentricities, binaries with qb ≳ 0.3 evolve towards coalescence, while lower mass ratio systems expand due to cbd torques. we discuss implications for population studies of massive black hole binaries, protostars in binary systems, and post-common envelope binaries observed by ground-based gravitational wave detectors. | orbital evolution of binaries in circumbinary discs |
we measure the mean free path ($\lambda _{\rm mfp,h\, \small {i}}$), photoionization rate ($\langle \gamma _{\rm h\, \small {i}} \rangle$), and neutral fraction ($\langle f_{\rm h\, \small {i}} \rangle$) of hydrogen in 12 redshift bins at 4.85 < z < 6.05 from a large sample of moderate resolution xshooter and esi qso absorption spectra. the fluctuations in ionizing radiation field are modelled by post-processing simulations from the sherwood suite using our new code 'extended reionization based on the code for ionization and temperature evolution' (ex-cite). ex-cite uses efficient octree summation for computing intergalactic medium attenuation and can generate large number of high resolution $\gamma _{\rm h\, \small {i}}$ fluctuation models. our simulation with ex-cite shows remarkable agreement with simulations performed with the radiative transfer code aton and can recover the simulated parameters within 1σ uncertainty. we measure the three parameters by forward-modelling the lyα forest and comparing the effective optical depth ($\tau _{\rm eff, h\, \small {i}}$) distribution in simulations and observations. the final uncertainties in our measured parameters account for the uncertainties due to thermal parameters, modelling parameters, observational systematics, and cosmic variance. our best-fitting parameters show significant evolution with redshift such that $\lambda _{\rm mfp,h\, \small {i}}$ and $\langle f_{\rm h\, \small {i}} \rangle$ decreases and increases by a factor ~6 and ~104, respectively from z ~ 5 to z ~ 6. by comparing our $\lambda _{\rm mfp,h\, \small {i}}$, $\langle \gamma _{\rm h\, \small {i}} \rangle$ and $\langle f_{\rm h\, \small {i}} \rangle$ evolution with that in state-of-the-art aton radiative transfer simulations and the thesan and coda-iii simulations, we find that our best-fitting parameter evolution is consistent with a model in which reionization completes by z ~ 5.2. our best-fitting model that matches the $\tau _{\rm eff, h\, \small {i}}$ distribution also reproduces the dark gap length distribution and transmission spike height distribution suggesting robustness and accuracy of our measured parameters. | measuring the photoionization rate, neutral fraction, and mean free path of h i ionizing photons at 4.9 ≤ z ≤ 6.0 from a large sample of xshooter and esi spectra |
molecular gas serves as a key probe of the complex interplay between black hole accretion and star formation in the host galaxies of active galactic nuclei (agns). we use co(2-1) observations from a new atacama large millimeter/submillimeter array survey, in conjunction with literature measurements, to investigate the molecular gas properties of a representative sample of 40 z < 0.3 palomar-green quasars, the largest and most sensitive study of molecular gas emission to date for nearby quasars. we find that the agn luminosity correlates with both the co luminosity and black hole mass, suggesting that agn activity is loosely coupled to the cold gas reservoir of the host. the observed strong correlation between host galaxy total infrared luminosity and agn luminosity arises from their common dependence on the molecular gas. we argue that the total infrared luminosity, at least for low-redshift quasars, can be used to derive reliable star formation rates for the host galaxy. the host galaxies of low-redshift quasars have a molecular gas content similar to that of star-forming galaxies of comparable stellar mass. moreover, they share similar gas kinematics, as evidenced by their co tully-fisher relation and the absence of detectable molecular outflows down to sensitive limits. there is no sign that agn feedback quenches star formation for the quasars in our sample. on the contrary, the abundant gas supply forms stars prodigiously, at a rate that places most of them above the star-forming main sequence and with an efficiency that rivals that of starburst systems. | agn feedback and star formation of quasar host galaxies: insights from the molecular gas |
core formation and runaway core collapse in models with self-interacting dark matter (sidm) significantly alter the central density profiles of collapsed haloes. using a forward modelling inference framework with simulated data-sets, we demonstrate that flux ratios in quadruple image strong gravitational lenses can detect the unique structural properties of sidm haloes, and statistically constrain the amplitude and velocity dependence of the interaction cross-section in haloes with masses between 106 and 1010 m⊙. measurements on these scales probe self-interactions at velocities below $30 \ \rm {km} \ \rm {s^{-1}}$, a relatively unexplored regime of parameter space, complimenting constraints at higher velocities from galaxies and clusters. we cast constraints on the amplitude and velocity dependence of the interaction cross-section in terms of σ20, the cross-section amplitude at $20 \ \rm {km} \ \rm {s^{-1}}$. with 50 lenses, a sample size available in the near future, and flux ratios measured from spatially compact mid-ir emission around the background quasar, we forecast $\sigma _{20} \lt 11\rm {\small {--}}23 \ \rm {cm^2} \rm {g^{-1}}$ at $95 {{\ \rm per\ cent}}$ ci, depending on the amplitude of the subhalo mass function, and assuming cold dark matter (cdm). alternatively, if $\sigma _{20} = 19.2 \ \rm {cm^2}\rm {g^{-1}}$ we can rule out cdm with a likelihood ratio of 20:1, assuming an amplitude of the subhalo mass function that results from doubly efficient tidal disruption in the milky way relative to massive elliptical galaxies. these results demonstrate that strong lensing of compact, unresolved sources can constrain sidm structure on sub-galactic scales across cosmological distances, and the evolution of sidm density profiles over several gyr of cosmic time. | strong lensing signatures of self-interacting dark matter in low-mass haloes |
this paper reports results of the third-year campaign of monitoring super-eddington accreting massive black holes (seambhs) in active galactic nuclei (agns) between 2014 and 2015. ten new targets were selected from the quasar sample of the sloan digital sky survey (sdss), which have generally been more luminous than the seambh candidates in the last two years. hβ lags ({τ }{{h}β }) in five of the 10 quasars have been successfully measured in this monitoring season. we find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known r h β-l 5100 relation. the five quasars have dimensionless accretion rates of \dot{{m}\quad }=10-103. combining these with measurements of the previous seambhs, we find that the reduction of hβ lags depends tightly on accretion rates, {τ }{{h}β }/{τ }r-l\propto {\dot{{m}}}-0.42, where {τ }r-l is the hβ lag from the normal r h β-l 5100 relation. fitting 63 mapped agns, we present a new scaling relation for the broad-line region: {r}{{h}β }={α }1{{\ell }}44{β 1} {min} [1,{(\dot{{m}}/{\dot{{m}}}c)}-{γ 1}], where {{\ell }}44={l}5100/{10}44 {erg} {{{s}}}-1 is the 5100 å continuum luminosity, and the coefficients are {α }1={29.6}-2.8+2.7 lt-day, {β }1={0.56}-0.03+0.03, {γ }1={0.52}-0.16+0.33, and {\dot{{m}}}c={11.19}-6.22+2.29. this relation is applicable to agns over a wide range of accretion rates, from 10-3 to 103. implications of this new relation are briefly discussed. | supermassive black holes with high accretion rates in active galactic nuclei. v. a new size-luminosity scaling relation for the broad-line region |
luminous distant quasars are unique probes of the high-redshift intergalactic medium (igm) and of the growth of massive galaxies and black holes in the early universe. absorption due to neutral hydrogen in the igm makes quasars beyond a redshift of z≃ 6.5 very faint in the optical z band, thus locating quasars at higher redshifts requires large surveys that are sensitive above 1 micron. we report the discovery of three new z\gt 6.5 quasars, corresponding to an age of the universe of \lt 850 myr, selected as z-band dropouts in the pan-starrs1 survey. this increases the number of known z\gt 6.5 quasars from four to seven. the quasars have redshifts of z = 6.50, 6.52, and 6.66, and include the brightest z-dropout quasar reported to date, pso j036.5078 + 03.0498 with {{m}1450}=-27.4. we obtained near-infrared spectroscopy for the quasars, and from the mg ii line, we estimate that the central black holes have masses between 5 × 108 and 4 × 109 {{m}⊙ } and are accreting close to the eddington limit ({{l}bol}/{{l}edd}=0.13-1.2). we investigate the ionized regions around the quasars and find near-zone radii of {{r}nz}=1.5-5.2 proper mpc, confirming the trend of decreasing near-zone sizes with increasing redshift found for quasars at 5.7\lt z\lt 6.4. by combining rnz of the ps1 quasars with those of 5.7\lt z\lt 7.1 quasars in the literature, we derive a luminosity-corrected redshift evolution of {{r}nz,corrected}=(7.2+/- 0.2)-(6.1+/- 0.7)× (z-6) mpc. however, the large spread in rnz in the new quasars implies a wide range in quasar ages and/or a large variation in the neutral hydrogen fraction along different lines of sight. based in part on observations collected at the european southern observatory, chile, programs 179.a-2010, 092.a-0150, 093.a-0863, and 093.a-0574, and at the centro astronómico hispano alemán (caha) at calar alto, operated jointly by the max-planck institut für astronomie and the instituto de astrofísica de andalucía (csic). this paper also includes data gathered with the 6.5 m magellan telescopes located at las campanas observatory, chile, at the mmt observatory, a joint facility of the university of arizona and the smithsonian institution, and with the lbt. | the identification of z-dropouts in pan-starrs1: three quasars at 6.5< z< 6.7 |
in a multiwavelength survey of 13 quasars at 5.8 ≲ z ≲ 6.5, which were preselected to be potentially young, we find five objects with extremely small proximity zone sizes that may imply uv-luminous quasar lifetimes of ≲100,000 yr. proximity zones are regions of enhanced transmitted flux in the vicinity of quasars that are sensitive to the quasars' lifetimes because the intergalactic gas has a finite response time to their radiation. we combine submillimeter observations from the atacama large millimetre array and the northern extended millimeter array, as well as deep optical and near-infrared spectra from the medium-resolution spectrograph on the very large telescope and on the keck telescopes, in order to identify and characterize these new young quasars, which provide valuable clues about the accretion behavior of supermassive black holes in the early universe and pose challenges on current black hole formation models to explain the rapid formation of billion-solar-mass black holes. we measure the quasars' systemic redshifts, black hole masses, eddington ratios, emission-line luminosities, and star formation rates of their host galaxies. combined with previous results, we estimate the fraction of young objects within the high-redshift quasar population at large to be 5% ≲ fyoung ≲ 10%. one of the young objects, pso j158-14, shows a very bright dust continuum flux (fcont = 3.46 ± 0.02 mjy), indicating a highly starbursting host galaxy with a star formation rate of approximately 1420 m⊙ yr-1. | detecting and characterizing young quasars. i. systemic redshifts and proximity zone measurements |
we report the discovery of 28 quasars and 7 luminous galaxies at 5.7 ≤ z ≤ 7.0. this is the tenth in a series of papers from the subaru high-z exploration of low-luminosity quasars (shellqs) project, which exploits the deep multiband imaging data produced by the hyper suprime-cam (hsc) subaru strategic program survey. the total number of spectroscopically identified objects in shellqs has now grown to 93 high-z quasars, 31 high-z luminous galaxies, 16 [o iii] emitters at z ∼ 0.8, and 65 galactic cool dwarfs (low-mass stars and brown dwarfs). these objects were found over 900 deg2, surveyed by hsc between 2014 march and 2018 january. the full quasar sample includes 18 objects with very strong and narrow lyα emission, whose stacked spectrum is clearly different from that of other quasars or galaxies. while the stacked spectrum shows n v λ1240 emission and resembles that of lower-z narrow-line quasars, the small lyα width may suggest a significant contribution from the host galaxies. thus, these objects may be composites of quasars and star-forming galaxies. | subaru high-z exploration of low-luminosity quasars (shellqs). x. discovery of 35 quasars and luminous galaxies at 5.7 ≤ z ≤ 7.0 |
radio sources at the highest redshifts can provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. the number of astronomical objects identified at z > 6 has increased dramatically over the last few years, but previously only three radio-loud (r2500 = fν,5 ghz/fν,2500 å > 10) sources had been reported at z > 6, with the most distant being a quasar at z = 6.18. here we present the discovery and characterization of pso j172.3556+18.7734, a radio-loud quasar at z = 6.823. this source has an mg ii-based black hole mass of ∼3 × 108 m⊙ and is one of the fastest accreting quasars, consistent with super-eddington accretion. the ionized region around the quasar is among the largest measured at these redshifts, implying an active phase longer than the average lifetime of the z ≳ 6 quasar population. from archival data, there is evidence that its 1.4 ghz emission has decreased by a factor of two over the last two decades. the quasar's radio spectrum between 1.4 and 3.0 ghz is steep (α = -1.31). assuming the measured radio slope and extrapolating to rest-frame 5 ghz, the quasar has a radio-loudness parameter r2500 ∼ 90. a second steep radio source (α = -0.83) of comparable brightness to the quasar is only 23"1 away (∼120 kpc at z = 6.82; projection probability <2%), but shows no optical or near-infrared counterpart. further follow-up is required to establish whether these two sources are physically associated. | the discovery of a highly accreting, radio-loud quasar at z = 6.82 |
as matter accretes onto the central supermassive black holes in active galactic nuclei (agns), x-rays are emitted. we present a population synthesis model that accounts for the summed x-ray emission from growing black holes; modulo the efficiency of converting mass to x-rays, this is effectively a record of the accreted mass. we need this population synthesis model to reproduce observed constraints from x-ray surveys: the x-ray number counts, the observed fraction of compton-thick agns [log (n h/cm-2) > 24], and the spectrum of the cosmic x-ray background (cxb), after accounting for selection biases. over the past decade, x-ray surveys by xmm-newton, chandra, nustar, and swift-bat have provided greatly improved observational constraints. we find that no existing x-ray luminosity function (xlf) consistently reproduces all these observations. we take the uncertainty in agn spectra into account and use a neural network to compute an xlf that fits all observed constraints, including observed compton-thick number counts and fractions. this new population synthesis model suggests that, intrinsically, 50% ± 9% (56% ± 7%) of all agns within z ≃ 0.1 (1.0) are compton-thick. | the accretion history of agns. i. supermassive black hole population synthesis model |
blazars are a sub-class of quasars with doppler boosted jets oriented close to the line of sight, and thus efficient probes of supermassive black hole growth and their environment, especially at high redshifts. here we report on very long baseline interferometry observations of a blazar j0906 + 6930 at z = 5.47, which enabled the detection of polarised emission and measurement of jet proper motion at parsec scales. the observations suggest a less powerful jet compared with the general blazar population, including lower proper motion and bulk lorentz factor. this coupled with a previously inferred high accretion rate indicate a transition from an accretion radiative power to a jet mechanical power based transfer of energy and momentum to the surrounding gas. while alternative scenarios could not be fully ruled out, our results indicate a possibly nascent jet embedded in and interacting with a dense medium resulting in a jet bending. | evolving parsec-scale radio structure in the most distant blazar known |
extended lyman alpha emission is now commonly detected around high-redshift galaxies through stacking and even on individual basis. despite recent observational advances, the physical origin of these lyman alpha haloes (lahs), as well as their relationships to galaxies, quasars, circumgalactic gas, and other environmental factors remains unclear. we present results from our new lyman alpha full radiative transfer code voroiltis which runs directly on the unstructured voronoi tessellation of cosmological hydrodynamical simulations. we make use of the tng50 simulation and simulate lahs from redshift z = 2 to z = 5, focusing on star-forming galaxies with $8.0 \lt \log _{10}{(m_\star /\rm {m}_\odot)} \lt 10.5$. while tng50 does not directly follow ionizing radiation, it includes an on-the-fly treatment for active galactic nuclei (agns) and ultraviolet background radiation with self-shielding, which are important processes impacting the cooling and ionization of the gas. based on this model, we present the predictions for the stacked radial surface brightness profiles of ly α as a function of galaxy mass and redshift. comparison with data from the muse udf at z > 3 reveals a promising level of agreement. we measure the correlations of lah size and central brightness with galaxy properties, finding that at the masses of $8.5 \le \log _{10} \left(m_\star /\rm {m}_\odot \right) \le 9.5$, physical lah sizes roughly double from z = 2 to z = 5. finally, we decompose the profiles into contributions from diffuse emission and scattered photons from star-forming regions. in our simulations, we find rescattered photons from star-forming regions to be the major source in observed lahs. unexpectedly, we find that the flattening of lah profiles at large radii becomes dominated by photons originating from other nearby haloes rather than diffuse emission itself. | the physical origins and dominant emission mechanisms of lyman alpha haloes: results from the tng50 simulation in comparison to muse observations |
we present co(2−1) and adjacent continuum observations of seven nearby radio-quiet type-2 quasars (qso2s) obtained with alma at ∼0.2″ resolution (370 pc at z ∼ 0.1). these qso2s are luminous (l[oiii] > 108.5 l⊙ ∼ mb < −23), and their host galaxies massive (m* ∼ 1011 m⊙). the co morphologies are diverse, including disks and interacting systems. two of the qso2s are red early-type galaxies with no co(2-1) detected. in the interacting galaxies, the central kiloparsec contains 18-25% of the total cold molecular gas, whereas in the spirals it is only ∼5-12%. j1010+0612 and j1430+1339 show double-peaked co flux maps along the major axis of the co disks that do not have an optical counterpart at the same angular resolution. based on our analysis of the ionized and molecular gas kinematics and millimeter continuum emission, these co morphologies are most likely produced by active galactic nucleus (agn) feedback in the form of outflows, jets, and/or shocks. the co kinematics of the qso2s with co(2−1) detections are dominated by rotation but also reveal noncircular motions. according to our analysis, these noncircular motions correspond to molecular outflows that are mostly coplanar with the co disks in four of the qso2s, and either to a coplanar inflow or vertical outflow in the case of j1010+0612. these outflows represent 0.2-0.7% of the qso2s' total molecular gas mass and have maximum velocities of 200-350 km s−1, radii from 0.4 to 1.3 kpc, and outflow mass rates of 8-16 m⊙ yr−1. these outflow properties are intermediate between those of the mild molecular outflows measured for seyfert galaxies and the fast and energetic outflows shown by ultra-luminous infrared galaxies. this suggests that it is not only agn luminosity that drives massive molecular outflows. other factors such as jet power, coupling between winds, jets, and/or ionized outflows and the co disks, and amount or geometry of dense gas in the nuclear regions might also be relevant. thus, although we do not find evidence for a significant impact of quasar feedback on the total molecular gas reservoirs and star formation rates, it appears to be modifying the distribution of cold molecular gas in the central kiloparsec of the galaxies. | the diverse cold molecular gas contents, morphologies, and kinematics of type-2 quasars as seen by alma |
we present results from the keck baryonic structure survey (kbss) including the first detailed measurements of the column densities, kinematics, and internal energy of metal-bearing gas within the virial radius (35-100 physical kpc) of eight ∼l* galaxies at z ∼ 2. from our full sample of 130 metal-bearing absorbers, we infer that halo gas is kinematically complex when viewed in singly, doubly, and triply ionized species. broad o vi and c iv absorbers are detected at velocities similar to the lower-ionization gas but with a very different kinematic structure, indicating that the circumgalactic medium (cgm) is multiphase. there is a high covering fraction of metal-bearing gas within 100 kpc, including highly ionized gas such as o vi; however, observations of a single galaxy probed by a lensed background qso suggest the size of metal-bearing clouds is small (<400 pc for all but the o vi-bearing gas). the mass in metals found within the halo is substantial, equivalent to ≳25% of the metal mass within the interstellar medium. the gas kinematics unambiguously show that 70% of galaxies with detected metal absorption have some unbound metal-enriched gas, suggesting galactic winds may commonly eject gas from halos at z ∼ 2. when modeled assuming that ions with different ionization potentials can originate within a single gaseous structure, significant thermal broadening is detected in cgm absorbers that dominates the internal energy of the gas. some 40% of the detected gas has temperatures in the range 104.5-5.5 k where cooling times are short, suggesting the cgm is dynamic, with constant heating or cooling to produce this short-lived thermal phase. | column density, kinematics, and thermal state of metal-bearing gas within the virial radius of z ∼ 2 star-forming galaxies in the keck baryonic structure survey |
we use the muse gas flow and wind (megaflow) survey to study the kinematics of extended disc-like structures of cold gas around z ≈ 1 star-forming galaxies. the combination of vlt/muse and vlt/uves observations allows us to connect the kinematics of the gas measured through mg ii quasar absorption spectroscopy to the kinematics and orientation of the associated galaxies constrained through integral field spectroscopy. confirming previous results, we find that the galaxy-absorber pairs of the megaflow survey follow a strong bimodal distribution, consistent with a picture of mg ii absorption being predominantly present in outflow cones and extended disc-like structures. this allows us to select a bona-fide sample of galaxy-absorber pairs probing these discs for impact paramometers of 10{-}70 {kpc}. we test the hypothesis that the disc-like gas is co-rotating with the galaxy discs, and find that for seven out of nine pairs the absorption velocity shares the sign of the disc velocity, disfavouring random orbits. we further show that the data are roughly consistent with inflow velocities and angular momenta predicted by simulations, and that the corresponding mass accretion rates are sufficient to balance the star formation rates. | muse gas flow and wind (megaflow) ii. a study of gas accretion around z ≈ 1 star-forming galaxies with background quasars |
the detection of quasars at z > 6 unveils the presence of supermassive black holes of a few billion solar masses. the rapid formation process of these extreme objects remains a fascinating and open issue. such discovery implies that seed black holes must have formed early on, and grown via either rapid accretion or bh/galaxy mergers. in this theoretical review, we discuss in detail various bh seed formation mechanisms and the physical processes at play during their assembly. we discuss the three most popular bh formation scenarios, involving the (i) core-collapse of massive stars, (ii) dynamical evolution of dense nuclear star clusters, (iii) collapse of a protogalactic metal free gas cloud. this article aims at giving a broad introduction and an overview of the most advanced research in the field. | formation of supermassive black hole seeds |
in this work, we study different types of dark energy (de) models in the framework of the cosmographic approach, with emphasis on the running vacuum models (rvms). we assess their viability using different information criteria and compare them with the so-called ghost de models (gdes) as well as with the concordance lambda cold dark matter (λcdm) model. we use the hubble diagrams for pantheon snia, quasars (qsos), gamma-ray bursts (grbs) as well as the data on baryonic acoustic oscillations (baos) in four different combinations. upon minimizing the χ2 function of the distance modulus in the context of the markov chain monte carlo method (mcmc), we put constraints on the current values of the standard cosmographic parameters in a model-independent way. it turns out that, in the absence of baos data, the various de models generally exhibit cosmographic tensions with the observations at the highest redshifts (namely with the qsos and grbs data). however, if we include the robust observations from baos to our cosmographic sample, the λcdm and rvms are clearly favoured against the gdes. finally, judging from the perspective of the deviance information criterion (dic), which enables us to compare models making use of the markov chains of the mcmc method, we conclude that the rvms are the preferred kind of de models. we find it remarkable that these models, which had been previously shown to be capable of alleviating the σ8 and h0 tensions, appear now also as the most successful ones at the level of the cosmographic analysis. | cosmographic approach to running vacuum dark energy models: new constraints using baos and hubble diagrams at higher redshifts |
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