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we discuss 6 ghz jvla observations covering a volume-limited sample of 178 low-redshift (0.2< z< 0.3) optically selected quasi-stellar objects (qsos). our 176 radio detections fall into two clear categories: (1) about 20% are radio-loud qsos (rlqs) with spectral luminosities of {l}6≳ {10}23.2 {{w}} {{hz}}-1 that are primarily generated in the active galactic nucleus (agn) responsible for the excess optical luminosity that defines a bona fide qso; and (2) the remaining 80% that are radio-quiet qsos (rqqs) that have {10}21≲ {l}6≲ {10}23.2 {{w}} {{hz}}-1 and radio sizes ≲ 10 {kpc}, and we suggest that the bulk of their radio emission is powered by star formation in their host galaxies. “radio-silent” qsos ({l}6≲ {10}21 {{w}} {{hz}}-1) are rare, so most rqq host galaxies form stars faster than the milky way; they are not “red and dead” ellipticals. earlier radio observations did not have the luminosity sensitivity of {l}6≲ {10}21 {{w}} {{hz}}-1 that is needed to distinguish between such rlqs and rqqs. strong, generally double-sided radio emission spanning \gg 10 {kpc} was found to be associated with 13 of the 18 rlq cores with peak flux densities of {s}{{p}}> 5 {mjy} {{beam}}-1 ({log}(l)≳ 24). the radio luminosity function of optically selected qsos and the extended radio emission associated with rlqs are both inconsistent with simple “unified” models that invoke relativistic beaming from randomly oriented qsos to explain the difference between rlqs and rqqs. some intrinsic property of the agns or their host galaxies must also determine whether or not a qso appears radio-loud. | radio-loud and radio-quiet qsos |
of the almost 40 star-forming galaxies at z≳ 5 (not counting quasi-stellar objects) observed in [cii] to date, nearly half are either very faint in [cii] or not detected at all, and fall well below expectations based on locally derived relations between star formation rate and [cii] luminosity. this has raised questions as to how reliable [cii] is as a tracer of star formation activity at these epochs and how factors such as metallicity might affect the [cii] emission. combining cosmological zoom simulations of galaxies with sígame (simulator of galaxy millimeter/submillimeter emission), we modeled the multiphased interstellar medium (ism) and its emission in [cii], as well as in [o i] and [o iii], from 30 main-sequence galaxies at z≃ 6 with star formation rates ∼3-23 m⊙ yr-1, stellar masses ∼ (0.7-8)× 109 m⊙, and metallicities ∼ (0.1-0.4)× z⊙. the simulations are able to reproduce the aforementioned [c ii] faintness of some normal star-forming galaxy sources at z≥ 5. in terms of [o i] and [o iii], very few observations are available at z≳ 5, but our simulations match two of the three existing z≳ 5 detections of [o iii] and are furthermore roughly consistent with the [o i] and [o iii] luminosity relations with star formation rate observed for local starburst galaxies. we find that the [c ii] emission is dominated by the diffuse ionized gas phase and molecular clouds, which on average contribute ∼66% and ∼27%, respectively. the molecular gas, which constitutes only ∼ 10 % of the total gas mass, is thus a more efficient emitter of [cii] than the ionized gas, which makes up ∼85% of the total gas mass. a principal component analysis shows that the [cii] luminosity correlates with the star formation activity of a galaxy as well as its average metallicity. the low metallicities of our simulations together with their low molecular gas mass fractions can account for their [cii] faintness, and we suggest that these factors may also be responsible for the [cii]-faint normal galaxies observed at these early epochs. | sígame simulations of the [cii], [oi], and [oiii] line emission from star-forming galaxies at z≃ 6 |
the identification of bright quasars at z ≳ 6 enables detailed studies of supermassive black holes, massive galaxies, structure formation, and the state of the intergalactic medium within the first billion years after the big bang. we present the spectroscopic confirmation of 55 quasars at redshifts 5.6 < z < 6.5 and uv magnitudes -24.5 < m 1450 < -28.5 identified in the optical pan-starrs1 and near-ir viking surveys (48 and 7, respectively). five of these quasars have independently been discovered in other studies. the quasar sample shows an extensive range of physical properties, including 17 objects with weak emission lines, 10 broad absorption line quasars, and 5 objects with strong radio emission (radio-loud quasars). there are also a few notable sources in the sample, including a blazar candidate at z = 6.23, a likely gravitationally lensed quasar at z = 6.41, and a z = 5.84 quasar in the outskirts of the nearby (d ~ 3 mpc) spiral galaxy m81. the blazar candidate remains undetected in noema observations of the [c ii] and underlying emission, implying a star formation rate <30-70 m ⊙ yr-1. a significant fraction of the quasars presented here lies at the foundation of the first measurement of the z ~ 6 quasar luminosity function from pan-starrs1 (introduced in a companion paper). these quasars will enable further studies of the high-redshift quasar population with current and future facilities. | the pan-starrs1 z > 5.6 quasar survey. ii. discovery of 55 quasars at 5.6 < z < 6.5 |
we investigate the constraints on the sum of neutrino masses ({{σ }}{m}ν ) using the most recent cosmological data, which combines the distance measurement from baryonic acoustic oscillation in the extended baryon oscillation spectroscopic survey dr14 quasar sample with the power spectra of temperature and polarization anisotropies in the cosmic microwave background from the planck 2015 data release. we also use other low-redshift observations, including the baryonic acoustic oscillation at relatively low redshifts, type ia supernovae, and the local measurement of the hubble constant. in the standard cosmological constant λ cold dark matter plus massive neutrino model, we obtain the 95% upper limit to be {{σ }}{m}ν < 0.129{ev} for the degenerate mass hierarchy, {{σ }}{m}ν < 0.159{ev} for the normal mass hierarchy, and {{σ }}{m}ν < 0.189{ev} for the inverted mass hierarchy. based on bayesian evidence, we find that the degenerate hierarchy is positively supported, and the current data combination cannot distinguish between normal and inverted hierarchies. assuming the degenerate mass hierarchy, we extend our study to non-standard cosmological models including generic dark energy, spatial curvature, and extra relativistic degrees of freedom, but find these models are not favored by the data. sw is supported by a grant from the research grant council of the hong kong special administrative region, china (14301214), dmx is supported by the national natural science foundation of china (11505018) and the chongqing science and technology plan project (cstc2015jvyj40031) | constraints on the sum of neutrino masses using cosmological data including the latest extended baryon oscillation spectroscopic survey dr14 quasar sample |
we report on ≈0.″35 (≈2kpc) resolution observations of the [c ii] and dust continuum emission from five z > 6 quasar host-companion galaxy pairs obtained with the atacama large millimeter/submillimeter array. the [c ii] emission is resolved in all galaxies, with physical extents of 3.2-5.4 kpc. the dust continuum is on-average 40% more compact, which results in larger [c ii] deficits in the center of the galaxies. however, the measured [c ii] deficits are fully consistent with those found at lower redshifts. four of the galaxies show [c ii] velocity fields that are consistent with ordered rotation, while the remaining six galaxies show no clear velocity gradient. all galaxies have high (∼80-200 km s-1) velocity dispersions, consistent with the interpretation that the interstellar medium (ism) of these high-redshift galaxies is turbulent. by fitting the galaxies with kinematic models, we estimate the dynamical mass of these systems, which ranges between (0.3 - >5.4) × 1010 m ⊙. for the three closest-separation galaxy pairs, we observe dust and [c ii] emission from gas in between and surrounding the galaxies, which is an indication that tidal interactions are disturbing the gas in these systems. although gas exchange in these tidal interactions could power luminous quasars, the existence of quasars in host galaxies without nearby companions suggests that tidal interactions are not the only viable method for fueling their active centers. these observations corroborate the assertion that accreting supermassive black holes do not substantially contribute to the [c ii] and dust continuum emission of the quasar host galaxies, and showcase the diverse ism properties of galaxies when the universe was less than one billion years old. | resolved [c ii] emission from z > 6 quasar host-companion galaxy pairs |
the most frequently proposed model for the origin of quasars holds that the high accretion rates seen in luminous active galactic nuclei (agn) are primarily triggered during major mergers between gas-rich galaxies. while plausible for decades, this model has only begun to be tested with statistical rigor in the past few years. here, we report on a hubble space telescope study to test this hypothesis for z = 2 quasars with high supermassive black hole masses ({m}{bh}={10}9{--}{10}10 {m}⊙), which dominate cosmic black hole growth at this redshift. we compare wide field camera 3 f160w (rest-frame v-band) imaging of 19 point source-subtracted quasar hosts to a matched sample of 84 inactive galaxies, testing whether the quasar hosts have greater evidence for strong gravitational interactions. using an expert ranking procedure, we find that the quasar hosts are uniformly distributed within the merger sequence of inactive galaxies, with no preference for quasars in high-distortion hosts. using a merger/non-merger cutoff approach, we recover distortion fractions of {f}{{m},{qso}}=0.39+/- 0.11 for quasar hosts and {f}{{m},{gal}}=0.30+/- 0.05 for inactive galaxies (distribution modes, 68% confidence intervals), with both measurements subjected to the same observational conditions and limitations. the slight enhancement in distorted fraction for quasar hosts over inactive galaxies is not significant, with a probability that the quasar fraction is higher p({f}{{m},{qso}}\gt {f}{{m},{gal}})=0.78 (0.78σ ), in line with results for lower mass and lower z agn. we find no evidence that major mergers are the primary triggering mechanism for the massive quasars that dominate accretion at the peak of cosmic quasar activity. | do the most massive black holes at z = 2 grow via major mergers? |
the presence of massive black holes (bhs) with masses of the order of $10^9\, {\rm m_\odot }$, powering bright quasars when the universe was less than 1 gyr old, poses strong constraints on their formation mechanism. several scenarios have been proposed to date to explain massive bh formation, from the low-mass seed bh remnants of the first generation of stars to the massive seed bhs resulting from the rapid collapse of massive gas clouds. however, the plausibility of some of these scenarios to occur within the progenitors of high-z quasars has not yet been thoroughly explored. in this work, we investigate, by combining dark-matter only n-body simulations with a semi-analytic framework, whether the conditions for the formation of massive seed bhs from synchronized atomic-cooling halo pairs and/or dynamically heated (dh) mini-haloes are fulfilled in the overdense regions where the progenitors of a typical high-redshift quasar host form and evolve. our analysis shows that the peculiar conditions in such regions, i.e. strong halo clustering and high star formation rates, are crucial to produce a non-negligible number of massive seed bh host candidates: we find ≈1400 dh metal-free mini-haloes, including one of these which evolves to a synchronized pair and ends up in the massive quasar-host halo by z = 6. this demonstrates that the progenitors of high-redshift quasar host haloes can harbour early massive seed bhs. our results further suggest that multiple massive seed bhs may form in or near the quasar host's progenitors, potentially merging at lower redshifts and yielding gravitational wave events. | forming massive seed black holes in high-redshift quasar host progenitors |
davies et al. established that for l* galaxies the fraction of baryons in the circumgalactic medium (cgm) is inversely correlated with the mass of their central supermassive black holes (bhs) in the eagle hydrodynamic simulation. the interpretation is that, over time, a more massive bh has provided more energy to transport baryons beyond the virial radius, which additionally reduces gas accretion and star formation. we continue this research by focusing on the relationship between the (1) bh masses (mbh), (2) physical and observational properties of the cgm, and (3) galaxy colours for milky way-mass systems. the ratio of the cumulative bh feedback energy over the gaseous halo binding energy is a strong predictor of the cgm gas content, with bhs injecting significantly higher than the binding energy resulting in gas-poor haloes. observable tracers of the cgm, including c iv, o vi, and h i absorption line measurements, are found to be effective tracers of the total z ∼ 0 cgm halo mass. we use high-cadence simulation outputs to demonstrate that bh feedback pushes baryons beyond the virial radius within 100 myr time-scales, but that cgm metal tracers take longer (0.5-2.5 gyr) to respond. secular evolution of galaxies results in blue, star-forming or red, passive populations depending on the cumulative feedback from bhs. the reddest quartile of galaxies with m* = 1010.2-10.7 m⊙ (median u - r = 2.28) has a cgm mass that is 2.5 times lower than the bluest quartile (u - r = 1.59). we propose observing strategies to indirectly ascertain fcgm via metal lines around galaxies with measured mbh. we predict statistically detectable declines in c iv and o vi covering fractions with increasing mbh for central galaxies with m* = 1010.2-10.7m⊙. | feedback from supermassive black holes transforms centrals into passive galaxies by ejecting circumgalactic gas |
we study the substructure content of the strong gravitational lens rxj1131-1231 through a forward modelling approach that relies on generating an extensive suite of realistic simulations. we use a semi-analytic merger tree prescription that allows us to stochastically generate substructure populations whose properties depend on the dark matter particle mass. these synthetic halos are then used as lenses to produce realistic mock images that have the same features, e.g. luminous arcs, quasar positions, instrumental noise and psf, as the data. we then analyse the data and the simulations in the same way with summary statistics that are sensitive to the signal being targeted and are able to constrain models of dark matter statistically using approximate bayesian computing (abc) techniques. {in this work, we focus on the thermal relic mass estimate and fix the semi-analytic descriptions of the substructure evolution based on recent literature.} we are able, based on the hst data for rxj1131-1231, to rule out a warm dark matter thermal relic mass below 2 kev at the 2σ confidence level. | lensing substructure quantification in rxj1131-1231: a 2 kev lower bound on dark matter thermal relic mass |
the assembly of the first super massive black holes (smbhs) at z ≳ 6 is still a subject of intense debate. if black holes (bhs) grow at their eddington rate, they must start from ≳104 m⊙ seeds formed by the direct collapse of gas. here, we explore the alternative scenario where ∼100 m⊙ bh remnants of the first stars grow at super-eddington rate via radiatively inefficient slim accretion discs. we use an improved version of the cosmological, data-constrained semi-analytic model gamete/qsodust, where we follow the evolution of nuclear bhs and gas cooling, disc and bulge formation of their host galaxies. adopting sdss j1148+5251 (j1148) at z = 6.4 as a prototype of luminous z ≳ 6 quasars, we find that ∼80 per cent of its smbh mass is grown by super-eddington accretion, which can be sustained down to z ∼ 10 in dense, gas-rich environments. the average bh mass at z ∼ 20 is mbh ≳ 104 m⊙, comparable to that of direct collapse bhs. at z = 6.4 the agn-driven mass outflow rate is consistent with the observations and the bh-to-bulge mass ratio is compatible with the local scaling relation. however, the stellar mass in the central 2.5 kpc is closer to the value inferred from co observations. finally, ∼20 per cent of j1148 progenitors at z = 7.1 have bh luminosities and masses comparable to ulas j1120+0641, suggesting that this quasar may be one of the progenitors of j1148. | super-eddington growth of the first black holes |
the emergence of the first black holes during the first billion years of cosmic history marks a key event in cosmology. their formation is part of the overall process of ending the cosmic dark ages, when the first stars appeared in low-mass dark matter haloes about a few 100 million years after the big bang. the first stars, galaxies, and black holes transformed the universe from its simple initial state into one of ever increasing complexity. we review recent progress on our emerging theoretical picture of how the first black holes appeared on the cosmic scene, and how they impacted the subsequent history of the universe. our focus is on supermassive black holes, in particular assessing possible pathways to the formation of the billion-solar-mass black holes inferred to power the luminous quasars at high redshifts. we conclude with a discussion of upcoming empirical probes, such as the james webb space telescope (jwst), and the laser interferometer space antenna (lisa), further ahead in time. | supermassive black holes in the early universe |
we use the panoramic survey telescope and rapid response system 1 survey (pan-starrs1, ps1) data to extend the sloan digital sky survey (sdss) stripe 82 quasar light curves. combining ps1 and sdss light curves provides a 15 yr baseline for 9248 quasars—5 yr longer than prior studies that used only sdss. we fit the light curves with the damped random walk (drw) model—a statistical description of their variability. we correlate the resulting drw model parameters: asymptotic variability amplitude sf∞, and characteristic timescale τ, with quasar physical properties—black hole mass, bolometric luminosity, and redshift. using simulated light curves, we find that a longer baseline allows us to better constrain the drw parameters. after adding ps1 data, the variability amplitude is a stronger function of the black hole mass and has a weaker dependence on quasar luminosity. in addition, the characteristic timescale τ dependence on quasar luminosity is marginally weaker. we also make predictions for the fidelity of drw model parameter retrieval when light curves will be further extended with zwicky transient facility and rubin observatory legacy survey of space and time data. finally, we show how updated drw parameters offer an independent method of discovering changing-look quasar candidates (clqsos). the candidates are outliers in terms of differences in magnitude and scatter between the sdss and ps1 segments. we identify 40 objects (35 newly reported) with a tenfold increase in the variability timescale between sdss and sdss-ps1 data due to a large change in brightness (over 0.5 mag)—characteristic for clqsos. | improving damped random walk parameters for sdss stripe 82 quasars with pan-starrs1 |
we determine the low-redshift x-ray luminosity function, active black hole mass function (bhmf), and eddington ratio distribution function (erdf) for both unobscured (type 1) and obscured (type 2) active galactic nuclei (agns), using the unprecedented spectroscopic completeness of the bat agn spectroscopic survey (bass) data release 2. in addition to a straightforward 1/v max approach, we also compute the intrinsic distributions, accounting for sample truncation by employing a forward-modeling approach to recover the observed bhmf and erdf. as previous bhmfs and erdfs have been robustly determined only for samples of bright, broad-line (type 1) agns and/or quasars, ours are the first directly observationally constrained bhmf and erdf of type 2 agns. we find that after accounting for all observational biases, the intrinsic erdf of type 2 agns is significantly more skewed toward lower eddington ratios than the intrinsic erdf of type 1 agns. this result supports the radiation-regulated unification scenario, in which radiation pressure dictates the geometry of the dusty obscuring structure around an agn. calculating the erdfs in two separate mass bins, we verify that the derived shape is consistent, validating the assumption that the erdf (shape) is mass-independent. we report the local agn duty cycle as a function of mass and eddington ratio, by comparing the bass active bhmf with the local mass function for all supermassive black holes. we also present the $\mathrm{log}n-\mathrm{log}s$ of the swift/bat 70 month sources. | bass. xxx. distribution functions of dr2 eddington ratios, black hole masses, and x-ray luminosities |
in the sixth of a series of papers reporting on a large reverberation mapping (rm) campaign of active galactic nuclei (agns) with high accretion rates, we present velocity-resolved time lags of hβ emission lines for nine objects observed in the campaign during 2012-2013. in order to correct the line broadening caused by seeing and instruments before analyzing the velocity-resolved rm, we adopt the richardson-lucy deconvolution to reconstruct their hβ profiles. the validity and effectiveness of the deconvolution are checked using monte carlo simulation. five among the nine objects show clear dependence of the time delay on velocity. mrk 335 and mrk 486 show signatures of gas inflow whereas the clouds in the broad-line regions (blrs) of mrk 142 and mcg +06-26-012 tend to be radial outflowing. mrk 1044 is consistent with having virialized motions. the lags of the remaining four are not velocity-resolvable. the velocity-resolved rm of super-eddington accreting massive black holes (seambhs) shows that they have diverse kinematics in their blrs. comparing with the agns with sub-eddington accretion rates, we do not find significant differences in the blr kinematics of seambhs. | supermassive black holes with high accretion rates in active galactic nuclei. vi. velocity-resolved reverberation mapping of the hβ line |
we cross-match the two currently largest all-sky photometric catalogs—mid-infrared wide-field infrared survey explorer and supercosmos scans of ukst/poss-ii photographic plates—to obtain a new galaxy sample that covers 3π steradians. in order to characterize and purify the extragalactic data set, we use external gama and sloan digital sky survey spectroscopic information to define quasar and star loci in multicolor space, aiding the removal of contamination from our extended source catalog. after appropriate data cleaning, we obtain a deep wide-angle galaxy sample that is approximately 95% pure and 90% complete at high galactic latitudes. the catalog contains close to 20 million galaxies over almost 70% of the sky, outside the zone of avoidance and other confused regions, with a mean surface density of more than 650 sources per square degree. using multiwavelength information from two optical and two mid-ir photometric bands, we derive photometric redshifts for all the galaxies in the catalog, using the annz framework trained on the final gama-ii spectroscopic data. our sample has a median redshift of {z}{med}=0.2, with a broad {dn}/{dz} reaching up to z > 0.4. the photometric redshifts have a mean bias of | δ z| ∼ {10}-3, a normalized scatter of σz= 0.033, and less than 3% outliers beyond 3σz . comparison with external data sets shows no significant variation of photo-z quality with sky position. together with the overall statistics, we also provide a more detailed analysis of photometric redshift accuracy as a function of magnitudes and colors. the final catalog is appropriate for “all-sky” three-dimensional (3d) cosmology to unprecedented depths, in particular through cross-correlations with other large-area surveys. it should also be useful for source preselection and identification in forthcoming surveys, such as taipan or wallaby. | wise × supercosmos photometric redshift catalog: 20 million galaxies over 3/pi steradians |
esa recently called for new "science ideas" to be investigated in terms of feasibility and technological developments -- for technologies not yet sufficiently mature. these ideas may in the future become candidates for m or l class missions within the esa science program. with the launch of gaia in december 2013, europe entered a new era of space astrometry following in the footsteps of the very successful hipparcos mission from the early 1990s. gaia is the successor to hipparcos, both of which operated in optical wavelengths, and gaia is two orders of magnitude more accurate in the five astrometric parameters and is surveying four orders of magnitude more stars in a vast volume of the milky way. the combination of the hipparcos/tycho-2 catalogues with the first early gaia data release will give improved proper motions over a long ~25 year baseline. the final gaia solution will also establish a new optical reference frame by means of quasars, by linking the optical counterparts of radio (vlbi) sources defining the orientation of the reference frame, and by using the zero proper motion of quasars to determine a non-rotating frame. a weakness of gaia is that it only operates at optical wavelengths. however, much of the galactic centre and the spiral arm regions, important for certain studies, are obscured by interstellar extinction and this makes it difficult for gaia to deeply probe. traditionally, this problem is overcome by switching to the infra-red but this was not possible with gaia's ccds. additionally, to scan the entire sky and make global absolute parallax measurements the spacecraft must have a constant rotation and this requires that the ccds operate in tdi mode, increasing their complexity. | gaianir: combining optical and near-infra-red (nir) capabilities with time-delay-integration (tdi) sensors for a future gaia-like mission |
the observed lyman-α flux power spectrum (fps) is suppressed on scales below {∼} 30 {km s}^{-1}. this cut-off could be due to the high temperature, t0, and pressure, p0, of the absorbing gas or, alternatively, it could reflect the free streaming of dark matter particles in the early universe. we perform a set of very high resolution cosmological hydrodynamic simulations in which we vary t0, p0, and the amplitude of the dark matter free streaming, and compare the fps of mock spectra to the data. we show that the location of the dark matter free-streaming cut-off scales differently with redshift than the cut-off produced by thermal effects and is more pronounced at higher redshift. we, therefore, focus on a comparison to the observed fps at z > 5. we demonstrate that the fps cut-off can be fit assuming cold dark matter, but it can be equally well fit assuming that the dark matter consists of ∼7 kev sterile neutrinos in which case the cut-off is due primarily to the dark matter free streaming. | the lyman-α forest as a diagnostic of the nature of the dark matter |
using data from the mosfire deep evolution field (mosdef) survey, we present a census of active galactic nucleus (agn)-driven ionized outflows in a sample of 159 agns at 1.4 ≤ z ≤ 3.8. the sample spans agn bolometric luminosities of 1044-47 erg s-1 and includes both quiescent and star-forming galaxies extending across 3 orders of magnitude in stellar mass. we identify and characterize outflows from the hβ, [o iii], hα, and [n ii] emission line spectra. we detect outflows in 17% of the agns, seven times more often than in a mass-matched sample of inactive galaxies in mosdef. the outflows are fast and galaxy-wide, with velocities of ∼400-3500 km s {}-1 and spatial extents of 0.3-11.0 kpc. the incidence of outflows among agns is independent of the stellar mass of the host galaxy, with outflows detected in both star-forming and quiescent galaxies. this suggests that outflows exist across different phases in galaxy evolution. we investigate relations between outflow kinematic, spatial, and energetic properties and both agn and host galaxy properties. our results show that agn-driven outflows are widespread in galaxies along the star-forming main sequence. the mass-loading factors of the outflows are typically 0.1-1 and increase with agn luminosity, capable of exceeding unity at {l}agn}≳ {10}46 {erg} {{{s}}}-1. in these more luminous sources, the ionized outflow alone is likely sufficient to regulate star formation and, when combined with outflowing neutral and molecular gas, may be able to quench star formation in their host galaxies. | the mosdef survey: a census of agn-driven ionized outflows at z = 1.4-3.8 |
the nanohertz gravitational wave background (gwb) is believed to be dominated by gw emission from supermassive black hole binaries (smbhbs). observations of several dual-active galactic nuclei (agn) strongly suggest a link between agn and smbhbs, given that these dual-agn systems will eventually form bound binary pairs. here we develop an exploratory smbhb population model based on empirically constrained quasar populations, allowing us to decompose the gwb amplitude into an underlying distribution of smbh masses, smbhb number density, and volume enclosing the gwb. our approach also allows us to self-consistently predict the number of local smbhb systems from the gwb amplitude. interestingly, we find the local number density of smbhbs implied by the common-process signal in the nanograv 12.5-yr data set to be roughly five times larger than previously predicted by other models. we also find that at most ~25% of smbhbs can be associated with quasars. furthermore, our quasar-based approach predicts ≳95% of the gwb signal comes from z ≲ 2.5, and that smbhbs contributing to the gwb have masses ≳108 m ⊙. we also explore how different empirical galaxy-black hole scaling relations affect the local number density of gw sources, and find that relations predicting more massive black holes decrease the local number density of smbhbs. overall, our results point to the important role that a measurement of the gwb will play in directly constraining the cosmic population of smbhbs, as well as their connections to quasars and galaxy mergers. | a quasar-based supermassive black hole binary population model: implications for the gravitational wave background |
we carried out spectroscopic monitoring of 21 low-redshift seyfert 1 galaxies using the kast double spectrograph on the 3 m shane telescope at lick observatory from 2016 april to 2017 may. targeting active galactic nuclei (agns) with luminosities of λ lλ (5100 å) ≈ 1044 erg s-1 and predicted hβ lags of ~20-30 days or black hole masses of 107-108.5 m ⊙, our campaign probes luminosity-dependent trends in broad-line region (blr) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. here we present the first results from the campaign, including hβ emission-line light curves, integrated hβ lag times (8-30 days) measured against v-band continuum light curves, velocity-resolved reverberation lags, line widths of the broad hβ components, and virial black hole mass estimates (107.1-108.1 m ⊙). our results add significantly to the number of existing velocity-resolved lag measurements and reveal a diversity of blr gas kinematics at moderately high agn luminosities. agn continuum luminosity appears not to be correlated with the type of kinematics that its blr gas may exhibit. follow-up direct modeling of this data set will elucidate the detailed kinematics and provide robust dynamical black hole masses for several objects in this sample. | the lick agn monitoring project 2016: velocity-resolved hβ lags in luminous seyfert galaxies |
context. galaxy-wide outflows driven by star formation and/or an active galactic nucleus (agn) are thought to play a crucial rule in the evolution of galaxies and the metal enrichment of the inter-galactic medium. direct measurements of these processes are still scarce and new observations are needed to reveal the nature of outflows in the majority of the galaxy population.aims: we combine extensive, spatially-resolved, multi-wavelength observations, taken as part of the close agn reference survey (cars), for the edge-on disc galaxy he 1353-1917 in order to characterise the impact of the agn on its host galaxy via outflows and radiation.methods: multi-color broad-band photometry was combined with spatially-resolved optical, near-infrared (nir) and sub-mm and radio observations taken with the multi-unit spectroscopy explorer (muse), the near-infrared integral field spectrometer (nifs), the atacama large millimeter array (alma), and the karl g. jansky very large array (vla) to map the physical properties and kinematics of the multi-phase interstellar medium.results: we detect a biconical extended narrow-line region ionised by the luminous agn orientated nearly parallel to the galaxy disc, extending out to at least 25 kpc. the extra-planar gas originates from galactic fountains initiated by star formation processes in the disc, rather than an agn outflow, as shown by the kinematics and the metallicity of the gas. nevertheless, a fast, multi-phase, agn-driven outflow with speeds up to 1000 km s-1 is detected close to the nucleus at 1 kpc distance. a radio jet, in connection with the agn radiation field, is likely responsible for driving the outflow as confirmed by the energetics and the spatial alignment of the jet and multi-phase outflow. evidence for negative agn feedback suppressing the star formation rate (sfr) is mild and restricted to the central kpc. but while any sfr suppression must have happened recently, the outflow has the potential to greatly impact the future evolution of the galaxy disc due to its geometrical orientation. conclusions.. our observations reveal that low-power radio jets can play a major role in driving fast, multi-phase, galaxy-scale outflows even in radio-quiet agn. since the outflow energetics for he 1353-1917 are consistent with literature, scaling relation of agn-driven outflows the contribution of radio jets as the driving mechanisms still needs to be systematically explored. | the close agn reference survey (cars). a massive multi-phase outflow impacting the edge-on galaxy he 1353-1917 |
blazars research is one of the hot topics of contemporary extragalactic astrophysics. that is because these sources are the most abundant type of extragalactic γ-ray sources and are suspected to play a central role in multimessenger astrophysics. we have used swift$\_$xrtproc, a tool to carry out an accurate spectral and photometric analysis of the swift-xrt data of all blazars observed by swift at least 50 times between december 2004 and the end of 2020. we present a database of x-ray spectra, best-fit parameter values, count rates and flux estimations in several energy bands of over 31 000 x-ray observations and single snapshots of 65 blazars. the results of the x-ray analysis have been combined with other multifrequency archival data to assemble the broad-band spectral energy distributions (seds) and the long-term light curves of all sources in the sample. our study shows that large x-ray luminosity variability on different time-scales is present in all objects. spectral changes are also frequently observed with a 'harder-when-brighter' or 'softer-when-brighter' behaviour depending on the sed type of the blazars. the peak energy of the synchrotron component (νpeak) in the sed of hbl blazars, estimated from the log-parabolic shape of their x-ray spectra, also exhibits very large changes in the same source, spanning a range of over two orders of magnitude in mrk421 and mrk501, the objects with the best data sets in our sample. | x-ray spectra, light curves and seds of blazars frequently observed by swift |
we study epicyclic oscillatory motion along circular geodesics of the simpson–visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. we give the frequencies of the orbital and epicyclic motion in a keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. we use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (hf qpos) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of hf qpos observational data from the surrounding of supermassive black holes. we demonstrate that this is really possible for wormholes with sufficiently high length parameter l. | epicyclic oscillations around simpson–visser regular black holes and wormholes |
we estimate the amplitude of the nano-hz stochastic gravitational wave background (gwb) resulting from an unresolved population of inspiralling massive black hole binaries (mbhbs). to this aim, we use the l-galaxies semi-analytical model applied on top of the millennium merger trees. the dynamical evolution of mbhbs includes dynamical friction, stellar and gas binary hardening, and gravitational wave (gw) feedback. at the frequencies proved by the pulsar timing array experiments, our model predicts an amplitude of ${\sim }1.2 \times 10^{-15}$ at ${\sim }3 \times 10^{-8}\, \rm hz$ in agreement with current estimations. the contribution to the background comes primarily from equal-mass binaries with chirp masses above $\rm 10^{8}\, m_{\odot }$. we then consider the recently detected common red noise in nanograv, ppta, and epta data, working under the hypothesis that it is indeed a stochastic gwb coming from mbhbs. by boosting the massive black hole growth via gas accretion, we show that our model can produce a signal with an amplitude $a\approx (2\!-\!3) \times 10^{-15}$. there are, however, difficulties in predicting this background level without mismatching key observational constraints such as the quasar bolometric luminosity functions or the local black hole mass function. this highlights how current and forthcoming gw observations can, for the first time, confront galaxy and black hole evolution models. | massive black hole evolution models confronting the n-hz amplitude of the stochastic gravitational wave background |
we survey the highly ionized circumgalactic media (cgm) of 29 blindly selected galaxies at 0.49< {z}gal}< 1.44 based on high signal-to-noise ratio ultraviolet spectra of z ≳ 1 quasi-stellar objects and the galaxy database from the cos absorption survey of baryon harbors (casbah). we detect the ne viii doublet in nine of the galaxies, and for gas with n({ne} {{viii}}) > {10}13.3 {cm}}-2 (> {10}13.5 {cm}}-2), we derive a {ne} {{viii}} covering fraction {f}c={75}-25+15 % ({44}-20+22 % ) within impact parameters ρ ≤ 200 kpc of m * = 109.5-11.5 m ⊙ galaxies and {f}c={70}-22+16 % ({f}c={42}-17+20 % ) within ρ ≤ 1.5 virial radii. we estimate the mass in {ne} {{viii}}-traced gas to be {m}gas}({ne} {{viii}})≥slant {10}9.5{m}⊙ {≤ft(z/{z}⊙ \right)}-1, or 6%-20% of the expected baryonic mass if the {ne} {{viii}} absorbers have solar metallicity. ionizing ne vii to {ne} {{viii}} requires 207 ev, and photons with this energy are scarce in the cgm. however, for the median halo mass and redshift of our sample, the virial temperature is close to the peak temperature for the {ne} {{viii}} ion, and the {ne} {{viii}}-bearing gas is plausibly collisionally ionized near this temperature. moreover, we find that photoionized {ne} {{viii}} requires cool and low-density clouds that would be highly underpressured (by approximately two orders of magnitude) relative to the putative, ambient virialized medium, complicating scenarios where such clouds could survive. thus, more complex (e.g., nonequilibrium) models may be required; this first statistical sample of {ne} viii absorber/galaxy systems will provide stringent constraints for future cgm studies. | the cos absorption survey of baryon harbors (casbah): warm-hot circumgalactic gas reservoirs traced by ne viii absorption |
we have detected in alma observations co j=6\to 5 emission from the nucleus of the seyfert galaxy ngc 1068. the low-velocity (up to ±70 km s-1 relative to systemic) co emission resolves into a 12 × 7 pc structure, roughly aligned with the nuclear radio source. higher-velocity emission (up to ±400 km s-1) is consistent with a bipolar outflow in a direction nearly perpendicular (≃80°) to the nuclear disk. the position-velocity diagram shows that in addition to the outflow, the velocity field may also contain rotation about the disk axis. these observations provide compelling evidence in support of the disk-wind scenario for the active galactic nucleus obscuring torus. | high-velocity bipolar molecular emission from an agn torus |
the importance of studying the gaia dr2 parallax zero-point by external means was underlined by the articles that accompanied the release, and initiated by several works making use of cepheids, eclipsing binaries, and asteroseismology. despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the gaia dr2 parallaxes. by combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the gaia parallax offset for nearly 3000 red-giant branch (rgb) and 2200 red clump (rc) stars observed by kepler, as well as about 500 and 700 red giants (all either in the rgb or rc phase) selected by the k2 galactic archaeology program in campaigns 3 and 6. engaging in a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the kepler field that are compatible with independent estimates from literature and open clusters. moreover, adding the k2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars. lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the gaia dr2 parallax offset, which will greatly benefit from the gain in precision with the third data release of gaia. | new light on the gaia dr2 parallax zero-point: influence of the asteroseismic approach, in and beyond the kepler field |
we examine the properties of the low-redshift circumgalactic medium (cgm) around star-forming and quenched galaxies in the simba cosmological hydrodynamic simulations, focusing on comparing h i and metal line absorption to observations from the cosmic origins spectrograph (cos)-halos and cos-dwarfs surveys. halo baryon fractions are generally ${\lesssim}50{{\ \rm per\ cent}}$ of the cosmic fraction due to stellar feedback at low masses, and jet-mode agn feedback at high masses. baryons and metals in the cgm of quenched galaxies are ${\gtrsim}90{{\ \rm per\ cent}}$ hot gas, while the cgm of star-forming galaxies is more multiphase. hot cgm gas has low metallicity, while warm and cool cgm gas have metallicity close to that of galactic gas. equivalent widths, covering fractions and total path absorption of h i and selected metal lines (mg ii, si iii, c iv, and o vi) around a matched sample of simba star-forming galaxies are mostly consistent with cos-halos and cos-dwarfs observations to ${\lesssim}0.4$ dex, depending on ion and assumed ionizing background. around matched quenched galaxies, absorption in all ions is lower, with h i absorption significantly underpredicted. metal-line absorption is sensitive to choice of photoionizing background; assuming recent backgrounds, simba matches o vi but underpredicts low ions, while an older background matches low ions but underpredicts o vi. simba reproduces the observed dichotomy of o vi absorption around star-forming and quenched galaxies. cgm metals primarily come from stellar feedback, while jet-mode agn feedback reduces absorption particularly for lower ions. | the low-redshift circumgalactic medium in simba |
context. the mechanism of dust formation in galaxies at high redshift is still unknown. asymptotic giant branch (agb) stars and explosions of supernovae (sne) are possible dust producers, and non-stellar processes may substantially contribute to dust production, for example grain growth in the interstellar medium.aims: our aim is to determine the contribution to dust production of agb stars and sne in nine galaxies at z ∼ 6-8.3, for which observations of dust have been recently attempted.methods: in order to determine the origin of the observed dust we have determined dust yields per agb star and sn required to explain the total amounts of dust in these galaxies.results: we find that agb stars were not able to produce the amounts of dust observed in the galaxies in our sample. in order to explain these dust masses, sne would have to have maximum efficiency and not destroy the dust which they formed.conclusions: therefore, the observed amounts of dust in the galaxies in the early universe were formed either by efficient supernovae or by a non-stellar mechanism, for instance the grain growth in the interstellar medium. | dust production scenarios in galaxies at z ∼6-8.3 |
high-z agns hosted in gas-rich galaxies are expected to grow through significantly obscured accretion phases. this may limit or bias their observability. in this work, we use bluetides, a large volume cosmological simulation of galaxy formation to examine quasar obscuration for the highest redshift (z ≥ 7) supermassive black holes residing in the centre of galaxies. we find that for the bright quasars, most of the high-column density gas (> 90 per cent) resides in the innermost regions of the host galaxy (typically within <10 ckpc), while the gas in the outskirts is a minor contributor to the nh. the brightest quasars can have large angular variations in galactic obscuration, over 2 orders of magnitude (ranging from column density nh ∼ 1021.5-24 cm-2), where the lines of sight with the lowest obscuration are those formed via strong gas outflows driven by agn feedback. the obscured fraction p(nh > 1023 cm-2) typically ranges from 0.6 to 1.0 for increasing lx (with lx > 1043 erg cm-1), with no clear trend of redshift evolution. due to the angular variation in nh, all relations between nh and lx, mbh, and galaxy host properties (global m*, mh2, and star formation rate) show appreciable scatter. the dust optical depth in the uv band τuv has tight positive correlation with nh. our dust-extincted uv luminosity function (uvlf) is about 1.5 dex lower than the intrinsic uvlf, implying that more than 99 per cent of the z ∼ 7 agns are heavily dust extincted and therefore would be missed by the uv-band observation. | qso obscuration at high redshift (z ≳ 7): predictions from the bluetides simulation |
we present agnfitter, a publicly available open-source algorithm implementing a fully bayesian markov chain monte carlo method to fit the spectral energy distributions (seds) of active galactic nuclei (agns) from the sub-millimeter to the uv, allowing one to robustly disentangle the physical processes responsible for their emission. agnfitter makes use of a large library of theoretical, empirical, and semi-empirical models to characterize both the nuclear and host galaxy emission simultaneously. the model consists of four physical emission components: an accretion disk, a torus of agn heated dust, stellar populations, and cold dust in star-forming regions. agnfitter determines the posterior distributions of numerous parameters that govern the physics of agns with a fully bayesian treatment of errors and parameter degeneracies, allowing one to infer integrated luminosities, dust attenuation parameters, stellar masses, and star-formation rates. we tested agnfitter’s performance on real data by fitting the seds of a sample of 714 x-ray selected agns from the xmm-cosmos survey, spectroscopically classified as type1 (unobscured) and type2 (obscured) agns by their optical-uv emission lines. we find that two independent model parameters, namely the reddening of the accretion disk and the column density of the dusty torus, are good proxies for agn obscuration, allowing us to develop a strategy for classifying agns as type1 or type2, based solely on an sed-fitting analysis. our classification scheme is in excellent agreement with the spectroscopic classification, giving a completeness fraction of ∼ 86 % and ∼ 70 % , and an efficiency of ∼ 80 % and ∼ 77 % , for type1 and type2 agns, respectively. | agnfitter: a bayesian mcmc approach to fitting spectral energy distributions of agns |
we present a hubble space telescope survey of extended [o iii] λ5007 emission for a sample of 12 nearby (z < 0.12), luminous type 2 quasars (qso2s), which we use to measure the extent and kinematics of their agn-ionized gas. we find that the size of the observed [o iii] regions scale with luminosity in comparison to nearby, less luminous seyfert galaxies and radially outflowing kinematics to exist in all targets. we report an average maximum outflow radius of ∼600 pc, with gas continuing to be kinematically influenced by the central active galactic nucleus (agn) out to an average radius of ∼1130 pc. these findings question the effectiveness of agns being capable of clearing material from their host bulge in the nearby universe and suggest that disruption of gas by agn activity may prevent star formation without requiring evacuation. additionally, we find a dichotomy in our targets when comparing [o iii] radial extent and nuclear fwhm, where qso2s with compact [o iii] morphologies typically possess broader nuclear emission lines. | hubble space telescope observations of extended [o iii]λ 5007 emission in nearby qso2s: new constraints on agn host galaxy interaction |
spinning black holes in the centres of galaxies can release powerful magnetised jets. when the jets are observed at angles of less than a few degrees to the line-of-sight, they are called blazars, showing variable non-thermal emission across the electromagnetic spectrum from radio waves to gamma rays. it is commonly believed that shock waves are responsible for this dissipation of jet energy. here we show that gamma-ray observations of the blazar 3c 279 with the space-borne telescope fermi-lat reveal a characteristic peak-in-peak variability pattern on time scales of minutes expected if the particle acceleration is instead due to relativistic magnetic reconnection. the absence of gamma-ray pair attenuation shows that particle acceleration takes place at a distance of ten thousand gravitational radii from the black hole where the fluid dynamical kink instability drives plasma turbulence. | gamma-ray flares from relativistic magnetic reconnection in the jet of the quasar 3c 279 |
we consider the largest observed sample including all intermediate-frequency peaked (ibl) and high-frequency peaked (hbl) flaring blazars above 100 gev up to redshift z = 0.6. we show that the best-fitting regression line of the emitted spectral indices γem(z) is a concave parabola decreasing as z increases, thereby implying a statistical correlation between the {γem(z)} distribution and z. this result contradicts our expectation that such a distribution should be zindependent. we argue that the above correlation does not arise from any selection bias. we show that our expectation naturally emerges provided that axion-like particles (alps) are put into the game. moreover, alps can also explain why flat spectrum radio quasars emit up to 400 gev, in sharp contradiction with conventional physics (cp). so, the combination of the two very different but consistent results - taken at face value - leads to a hint at an alp with mass m = o (10^{-10} ev) and two-photon coupling in the range 2.94 × 10^{- 12} gev^{- 1} <g_{a γ γ } <0.66 × 10^{- 10} gev^{- 1}. as a bonus, the universe would become considerably more transparent above energies e ≳ 1 tev than dictated by cp. our prediction can be checked not only by the new generation of observatories like cta, hawc, gamma-400, lhaaso, taiga-hiscore, and herd, but also thanks to the planned laboratory experiments alps ii (upgraded), stax, iaxo and with other techniques now being developed by avignone and collaborators. | hint at an axion-like particle from the redshift dependence of blazar spectra |
we study the relation between accretion rate (in terms of l/ledd) and shape of the hard x-ray spectral energy distribution (namely the photon index γx) for a large sample of 228 hard x-ray-selected, low-redshift active galactic nuclei (agns), drawn from the swift/bat agn spectroscopic survey (bass). this includes 30 agns for which black hole mass (and therefore l/ledd) is measured directly through masers, spatially resolved gas or stellar dynamics, or reverberation mapping. the high-quality and broad energy coverage of the data provided through bass allow us to examine several alternative determinations of both γx and l/ledd. for the bass sample as a whole, we find a statistically significant, albeit very weak correlation between γx and l/ledd. the best-fitting relations we find, γx ≃ 0.15 log l/ledd + const., are considerably shallower than those reported in previous studies. moreover, we find no corresponding correlations among the subsets of agn with different mbh determination methodology. in particular, we find no robust evidence for a correlation when considering only those agn with direct or single-epoch mbh estimates. this latter finding is in contrast to several previous studies which focused on z > 0.5 broad-line agn. we discuss this tension and conclude that it can be partially accounted for if one adopts a simplified, power-law x-ray spectral model, combined with l/ledd estimates that are based on the continuum emission and on single-epoch broad-line spectroscopy in the optical regime. we finally highlight the limitations on using γx as a probe of supermassive black hole evolution in deep extragalactic x-ray surveys. | bat agn spectroscopic survey (bass) - vi. the γx-l/ledd relation |
we report the serendipitous detection of a 0.2 l*, lyα emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background qso sightline. a high-resolution spectrum of the qso reveals a partial lyman-limit absorption system ({n}_h i=10^{16.94± 0.10} cm-2) with many associated metal absorption lines at the same redshift as the foreground galaxy. using photoionization models that carefully treat measurement errors and marginalize over uncertainties in the shape and normalization of the ionizing radiation spectrum, we derive the total hydrogen column density {n}_h=10^{19.4± 0.3} cm^{-2}, and show that all the absorbing clouds are metal enriched, with z = 0.1-0.6 z⊙. these metallicities and the system's large velocity width (436 km s- 1) suggest the gas is produced by an outflowing wind. using an expanding shell model we estimate a mass outflow rate of ∼5 m⊙ yr-1. our photoionization model yields extremely small sizes (<100-500 pc) for the absorbing clouds, which we argue is typical of high column density absorbers in the circumgalactic medium (cgm). given these small sizes and extreme kinematics, it is unclear how the clumps survive in the cgm without being destroyed by hydrodynamic instabilities. the small cloud sizes imply that even state-of-the-art cosmological simulations require more than a 1000-fold improvement in mass resolution to resolve the hydrodynamics relevant for cool gas in the cgm. | metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
we report the detection of adfs-27, a dusty, starbursting major merger at a redshift of z = 5.655, using the atacama large millimeter/submillimeter array (alma). adfs-27 was selected from herschel/spectral and photometric imaging receiver (spire) and apex/laboca data as an extremely red “870 μm riser” (i.e., {s}250μ {{m}}< {s}350μ {{m}}< {s}500μ {{m}}< {s}870μ {{m}}), demonstrating the utility of this technique to identify some of the highest-redshift dusty galaxies. a scan of the 3 mm atmospheric window with alma yields detections of co(j = 5 → 4) and co(j = 6 → 5) emission, and a tentative detection of h2o(211 → 202) emission, which provides an unambiguous redshift measurement. the strength of the co lines implies a large molecular gas reservoir with a mass of m gas = 2.5 × 1011 ({α }{co}/0.8)(0.39/{r}51) m ⊙, sufficient to maintain its ∼2400 m ⊙ yr-1 starburst for at least ∼100 myr. the 870 μm dust continuum emission is resolved into two components, 1.8 and 2.1 kpc in diameter, separated by 9.0 kpc, with comparable dust luminosities, suggesting an ongoing major merger. the infrared luminosity of l ir ≃ 2.4 × 1013 l ⊙ implies that this system represents a binary hyper-luminous infrared galaxy, the most distant of its kind presently known. this also implies star formation rate surface densities of {{{σ }}}{sfr}=730 and 750 m ⊙ yr-1 kpc2, consistent with a binary “maximum starburst.” the discovery of this rare system is consistent with a significantly higher space density than previously thought for the most luminous dusty starbursts within the first billion years of cosmic time, easing tensions regarding the space densities of z ∼ 6 quasars and massive quiescent galaxies at z ≳ 3. | rise of the titans: a dusty, hyper-luminous “870 μm riser” galaxy at z ∼ 6 |
the pan-starrs1 (ps1) 3π survey is a comprehensive optical imaging survey of three quarters of the sky in the grizy broad-band photometric filters. we present the methodology used in assembling the source classification and photometric redshift (photo-z) catalogue for ps1 3π data release 1, titled pan-starrs1 source types and redshifts with machine learning (ps1-strm). for both main data products, we use neural network architectures, trained on a compilation of public spectroscopic measurements that has been cross-matched with ps1 sources. we quantify the parameter space coverage of our training data set, and flag extrapolation using self-organizing maps. we perform a monte carlo sampling of the photometry to estimate photo-z uncertainty. the final catalogue contains 2902 054 648 objects. on our validation data set, for non-extrapolated sources, we achieve an overall classification accuracy of $98.1{{\ \rm per\ cent}}$ for galaxies, $97.8{{\ \rm per\ cent}}$ for stars, and $96.6{{\ \rm per\ cent}}$ for quasars. regarding the galaxy photo-z estimation, we attain an overall bias of ⟨δznorm⟩ = 0.0005, a standard deviation of σ(δznorm) = 0.0322, a median absolute deviation of mad(δznorm) = 0.0161, and an outlier fraction of $p\left(|\delta z_{\mathrm{norm}}|\gt 0.15\right)=1.89{{\ \rm per\ cent}}$. the catalogue will be made available as a high-level science product via the mikulski archive for space telescopes. | ps1-strm: neural network source classification and photometric redshift catalogue for ps1 3π dr1 |
we present the quasar luminosity function at z ∼ 5 derived from the optical wide-field survey data obtained as a part of the subaru strategic program (ssp) with the hyper suprime-cam (hsc). from a ∼81.8 deg2 area in the wide layer of the hsc-ssp survey, we selected 224 candidates of low-luminosity quasars at z ∼ 5 by adopting the lyman-break method down to i = 24.1 mag. based on our candidates and spectroscopically confirmed quasars from the sloan digital sky survey (sdss), we derived the quasar luminosity function at z ∼ 5, covering a wide luminosity range of -28.76 < m1450 < -22.32 mag. we found that the quasar luminosity function is fitted by a double power-law model with a break magnitude of ${m}_{1450}^{* }=-{25.05}_{-0.24}^{+0.10}$ mag. the inferred number density of low-luminosity quasars is lower, and the derived faint-end slope, $-{1.22}_{-0.10}^{+0.03}$ , is flatter than those of previous studies at z ∼ 5. a compilation of the quasar luminosity function at 4 ≤ z ≤ 6 from the hsc-ssp suggests that there is little redshift evolution in the break magnitude and in the faint-end slope within this redshift range, although previous studies suggest that the faint-end slope becomes steeper at higher redshifts. the number density of low-luminosity quasars decreases more rapidly from z ∼ 5 to z ∼ 6 than from z ∼ 4 to z ∼ 5. | the faint end of the quasar luminosity function at z ∼ 5 from the subaru hyper suprime-cam survey |
the near earth object wide-field infrared survey explorer (neowise) reactivation mission released data from its first full year of observations in 2015. this data set includes ∼2.5 million exposures in each of w1 and w2, effectively doubling the amount of wise imaging available at 3.4 μm and 4.6 μm relative to the allwise release. we have created the first ever full-sky set of coadds combining all publicly available w1 and w2 exposures from both the allwise and neowise-reactivation (neowiser) mission phases. we employ an adaptation of the unwise image coaddition framework, which preserves the native wise angular resolution and is optimized for forced photometry. by incorporating two additional scans of the entire sky, we not only improve the w1/w2 depths, but also largely eliminate time-dependent artifacts such as off-axis scattered moonlight. we anticipate that our new coadds will have a broad range of applications, including target selection for upcoming spectroscopic cosmology surveys, identification of distant/massive galaxy clusters, and discovery of high-redshift quasars. in particular, our full-depth allwise+neowiser coadds will be an important input for the dark energy spectroscopic instrument selection of luminous red galaxy and quasar targets. our full-depth w1/w2 coadds are already in use within the decam legacy survey (decals) and mayall z-band legacy survey (mzls) reduction pipelines. much more work still remains in order to fully leverage neowiser imaging for astrophysical applications beyond the solar system. | full-depth coadds of the wise and first-year neowise-reactivation images |
we report the first results of a survey on 74 narrow-line seyfert 1 galaxies (nls1s) carried out in 2015 with the karl g. jansky very large array (jvla) at 5 ghz in a-configuration. so far, this is the largest survey aimed to image the radio continuum of nls1s. we produced radio maps in order to compare the general properties of three different samples of objects: radio-quiet nls1s (rqnls1s), steep-spectrum radio-loud nls1s (s-nls1s), and flat-spectrum radio-loud nls1s (f-nls1s). we find that the three classes correspond to different radio morphologies, with f-nls1s being more compact, and rqnls1s often showing diffuse emission on kpc scales. we also find that f-nls1s might be low-luminosity and possibly young blazars, and that s-nls1s are part of the parent population of f-nls1s. dedicated studies to rqnls1s are needed to fully understand their role in the unification pictures. the reduced images (fits files) are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/614/a87 | radio-emitting narrow-line seyfert 1 galaxies in the jvla perspective |
among more than 200 quasars known at z ≳ 6, only one object, j0100+2802 (z = 6.327), was found hosting a >1010 m ⊙ supermassive black hole. in order to investigate the host galaxy properties of j0100+2802, we performed multi-band alma observations, aiming at mapping the dust continuum, [c ii] and co(6-5) emission lines with subkiloparsec scale resolution, as well as detecting high-j co lines in co(11-10), co(10-9), and co(7-6). the galaxy size is measured to be r major = 3.6 ± 0.2 kpc from the high-resolution continuum observations. no ordered motion on kiloparsec scales was found in either the [c ii] or the co(6-5) emission. the velocity dispersion is measured to be 161 ± 7 km s-1, which is about three times smaller than that estimated from the local m-σ relation. in addition, we found that the co emission is more concentrated (a factor of 1.8 ± 0.4) than the [c ii] emission. together with co(2-1) detected by the very large array (vla), we measured the co spectral line energy distribution, which is best fit by a two-component model that includes a cool component at ∼24 k with a density of {n}({{{h}}2)}={10}4.5 cm-3, and a warm component at ∼224 k with a density of {n}({{{h}}2)}={10}3.6 cm-3. we also fit the dust continuum with a graybody model. this indicated that the continuum has either a high dust emissivity β ≳ 2 or a hot dust temperature t dust ≳ 60 k, or a combination of these two factors. the highly excited co emission and hot dust temperature suggest that the powerful active galactic nucleus in j0100+2802 could contribute to the gas and dust heating, but future observations are needed to confirm this. | spatially resolved interstellar medium and highly excited dense molecular gas in the most luminous quasar at z = 6.327 |
we study the extended chandra deep field-south very large array sample, which reaches a flux density limit at 1.4 ghz of 32.5 μjy at the field centre and redshift ∼4, and covers ∼0.3 deg2. number counts are presented for the whole sample while the evolutionary properties and luminosity functions are derived for active galactic nuclei (agn). the faint radio sky contains two totally distinct agn populations, characterized by very different evolutions, luminosity functions, and eddington ratios: radio-quiet (rq)/radiative-mode and radio-loud (rl)/jet-mode agn. the radio power of rq agn evolves ∼ ∝(1+z)^{2.5}, similarly to star-forming galaxies, while the number density of rl ones has a peak at z ∼ 0.5 and then declines at higher redshifts. the number density of radio-selected rq agn is consistent with that of x-ray selected agn, which shows that we are sampling the same population. the unbiased fraction of radiative-mode rl agn, derived from our own and previously published data, is a strong function of radio power, decreasing from ∼0.5 at p1.4 ghz ∼ 1024 w hz-1 to ∼0.04 at p1.4 ghz ∼ 1022 w hz-1. thanks to our enlarged sample, which now includes ∼700 radio sources, we also confirm and strengthen our previous results on the source population of the faint radio sky: star-forming galaxies start to dominate the radio sky only below ∼0.1 mjy, which is also where rq agn overtake rl ones. | radio-faint agn: a tale of two populations |
atacama large millimeter array [c ii] line and continuum observations of five redshift z> 6 quasars are presented. this sample was selected to probe quasars with lower black hole mass than most previous studies. we find a wide dispersion in properties with cfhqs j0216-0455, a low-luminosity quasar with absolute magnitude {m}1450=-22.2, remaining undetected implying a limit on the star formation rate in the host galaxy of ≲ 10 {m}⊙{{yr}}-1, whereas other host galaxies have star formation rates up to hundreds of solar masses per year. two other quasars have particularly interesting properties. vimos2911 is one of the least luminous z> 6 quasars known with {m}1450=-23.1, yet its host galaxy is experiencing a very powerful starburst. pso j167-13 has a broad and luminous [c ii] line and a neighboring galaxy a projected distance of 5 kpc away that is also detected in the [c ii] line and continuum. combining with similar observations from the literature, we study the ratio of the [c ii] line to the far-infrared luminosity, finding that this ratio increases at high redshift at a fixed far-infrared luminosity, likely due to lower dust content, lower metallicity and/or higher gas masses. we compile a sample of 21 high-redshift quasars with dynamical masses and investigate the relationship between black hole mass and dynamical mass. the new observations presented here reveal dynamical masses consistent with the relationship defined by local galaxies. however, the full sample shows a very wide scatter across the black hole mass-dynamical mass plane, whereas both the local relationship and simulations of high-redshift quasars show a much lower dispersion in dynamical mass. | a wide dispersion in star formation rate and dynamical mass of 108 solar mass black hole host galaxies at redshift 6 |
we use cosmological hydrodynamic simulations with stellar feedback from the fire (feedback in realistic environments) project to study the physical nature of lyman limit systems (llss) at z ≤ 1. at these low redshifts, llss are closely associated with dense gas structures surrounding galaxies, such as galactic winds, dwarf satellites and cool inflows from the intergalactic medium. our analysis is based on 14 zoom-in simulations covering the halo mass range mh ≈ 109-1013 m⊙ at z = 0, which we convolve with the dark matter halo mass function to produce cosmological statistics. we find that the majority of cosmologically selected llss are associated with haloes in the mass range 1010 ≲ mh ≲ 1012 m⊙. the incidence and h i column density distribution of simulated absorbers with columns in the range 10^{16.2} ≤ n_{h i} ≤ 2× 10^{20} cm-2 are consistent with observations. high-velocity outflows (with radial velocity exceeding the halo circular velocity by a factor of ≳ 2) tend to have higher metallicities ([x/h] ∼ -0.5) while very low metallicity ([x/h] < -2) llss are typically associated with gas infalling from the intergalactic medium. however, most llss occupy an intermediate region in metallicity-radial velocity space, for which there is no clear trend between metallicity and radial kinematics. the overall simulated lls metallicity distribution has a mean (standard deviation) [x/h] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies, but consistent with llss arising from haloes with a broad range of masses and metallicities. | low-redshift lyman limit systems as diagnostics of cosmological inflows and outflows |
we present the first data release (dr1) of the uves spectral quasar absorption database (squad), comprising 467 fully reduced, continuum-fitted high-resolution quasar spectra from the ultraviolet and visual echelle spectrograph (uves) on the european southern observatory's very large telescope. the quasars have redshifts z = 0-5, and a total exposure time of 10 million seconds provides continuum-to-noise ratios of 4-342 (median 20) per 2.5 {km s}^{-1} pixel at 5500 å. the squad spectra are fully reproducible from the raw, archival uves exposures with open-source software, including our uves_popler tool for combining multiple extracted echelle exposures which we document here. all processing steps are completely transparent and can be improved upon or modified for specific applications. a primary goal of squad is to enable statistical studies of large quasar and absorber samples, and we provide tools and basic information to assist three broad scientific uses: studies of damped lyman-α systems (dlas), absorption-line surveys, and time-variable absorption lines. for example, we provide a catalogue of 155 dlas whose lyman-α lines are covered by the dr1 spectra, 18 of which are reported for the first time. the h i column densities of these new dlas are measured from the dr1 spectra. dr1 is publicly available and includes all reduced data and information to reproduce the final spectra. | the uves spectral quasar absorption database (squad) data release 1: the first 10 million seconds |
we use a semi-analytic model to explore the potential impact of a brief and violent period of radio-loud accretion on to black holes (the radio scream) during the cosmic dawn on the h i hyperfine 21 cm signal. we find that radio emission from supermassive black hole seeds can impact the global 21 cm signal at the level of tens to hundreds of per cent provided that they were as radio loud as z ≈ 1 black holes and obscured by gas with column depths of nh ≳ 1023 cm-2. we determine plausible sets of parameters that reproduce some of the striking features of the edges absorption feature including its depth, timing, and side steepness while producing radio/x-ray backgrounds and source counts that are consistent with published limits. scenarios yielding a dramatic 21 cm signature also predict large populations of ∼μjy point sources that will be detectable in future deep surveys from the square kilometer array (ska). thus, 21 cm measurements, complemented by deep point-source surveys, have the potential to constrain optimistic scenarios where supermassive black hole progenitors were radio loud. | the radio scream from black holes at cosmic dawn: a semi-analytic model for the impact of radio-loud black holes on the 21 cm global signal |
we describe the kinematics of circumgalactic gas near the galactic plane, combining new measurements of galaxy rotation curves and spectroscopy of background quasars. the sightlines pass within 19-93 kpc of the target galaxy and generally detect mg ii absorption. the mg ii doppler shifts have the same sign as the galactic rotation, so the cold gas co-rotates with the galaxy. because the absorption spans a broader velocity range than disk rotation can explain, we explore simple models for the circumgalactic kinematics. gas spiraling inwards (near the disk plane) offers a successful description of the observations. an appendix describes the addition of tangential and radial gas flows and illustrates how the sign of the disk inclination produces testable differences in the projected line-of-sight velocity range. this inflow interpretation implies that cold flow disks remain common down to redshift z ≈ 0.2 and prolong star formation by supplying gas to the disk. some of the observations were obtained with the apache point observatory 3.5 meter telescope, which is owned and operated by the astrophysical research consortium. | quasars probing galaxies. i. signatures of gas accretion at redshift approximately 0.2 |
we report on the first alma observation of the co(3-2) and rest-frame ∼340 ghz continuum emission in pds 456, which is the most luminous, radio-quiet qso in the local universe (z ≃ 0.18), with a bolometric luminosity lbol ∼ 1047 erg s-1. alma angular resolution allowed us to map scales as small as ∼700 pc. the molecular gas reservoir traced by the core of the very bright co(3-2) emission line is distributed in a compact rotating disk, with a size of ∼1.3 kpc, seen close to face-on (i ∼ 25 deg). fast co(3-2) emission in the velocity range v ∈ [ - 1000, 500] km s-1 is also present. specifically, we detect several blue-shifted clumps out to ∼5 kpc from the nucleus, in addition to a compact (r ≲ 1.2 kpc), broad emission component. these components reveal a galaxy-wide molecular outflow, with a total mass mmolout ∼ 2.5 × 108 m⊙ (for an αco = 0.8 m⊙ (k km s-1 pc2)-1) and a mass outflow rate ṁmol ∼ 290 m⊙ yr-1. the corresponding depletion time is τdep ∼ 8 myr, shorter than the rate at which the molecular gas is converted into stars, indicating that the detected outflow is potentially able to quench star-formation in the host. the momentum flux of the molecular outflow normalised to the radiative momentum output (i.e. lbol/c) is ≲1, comparable to that of the x-ray ultra-fast outflow (ufo) detected in pds 456. this is at odds with the expectations for an energy-conserving expansion suggested for most of the large-scale outflows detected in low-luminosity agns so far. we suggest three possible scenarios that may explain this observation: (i) in very luminous agns such as our target the molecular gas phase is tracing only a fraction of the total outflowing mass; (ii) a small coupling between the shocked gas by the ufo and the host-galaxy interstellar medium (ism); and (iii) agn radiation pressure may be playing an important role in driving the outflow. | the gentle monster pds 456. kiloparsec-scale molecular outflow and its implications for qso feedback |
we provide a comprehensive census of the near-infrared (nir, 0.8-2.4 μm) spectroscopic properties of 102 nearby (z < 0.075) active galactic nuclei (agn), selected in the hard x-ray band (14-195 kev) from the swift-burst alert telescope survey. with the launch of the james webb space telescope, this regime is of increasing importance for dusty and obscured agn surveys. we measure black hole masses in 68 per cent (69/102) of the sample using broad emission lines (34/102) and/or the velocity dispersion of the ca ii triplet or the co band-heads (46/102). we find that emission-line diagnostics in the nir are ineffective at identifying bright, nearby agn galaxies because [fe ii] 1.257 μm/paβ and h2 2.12 μm/brγ identify only 25 per cent (25/102) as agn with significant overlap with star-forming galaxies and only 20 per cent of seyfert 2 have detected coronal lines (6/30). we measure the coronal line emission in seyfert 2 to be weaker than in seyfert 1 of the same bolometric luminosity suggesting obscuration by the nuclear torus. we find that the correlation between the hard x-ray and the [si vi] coronal line luminosity is significantly better than with the [o iii] λ5007 luminosity. finally, we find 3/29 galaxies (10 per cent) that are optically classified as seyfert 2 show broad emission lines in the nir. these agn have the lowest levels of obscuration among the seyfert 2s in our sample (log nh < 22.43 cm-2), and all show signs of galaxy-scale interactions or mergers suggesting that the optical broad emission lines are obscured by host galaxy dust. | bat agn spectroscopic survey - iv: near-infrared coronal lines, hidden broad lines, and correlation with hard x-ray emission |
based on broadband spectral energy distributions (seds), we estimate the jet physical parameters of 1392 γ-ray-loud active galactic nuclei (agns), the largest sample so far. the (sed) jet power and magnetization parameter are derived for these agns. out of these sources, the accretion disk luminosity of 232 sources and (extended) kinetic jet powers of 159 sources are compiled from archived papers. we find the following. (1) flat-spectrum radio quasars (fsrqs) and bl lacs are well separated by {{γ }}=-0.127{log}{l}γ +8.18 in the γ-ray luminosity versus photon index plane with a success rate of 88.6%. (2) most fsrqs present a (sed) jet power larger than the accretion power, which suggests that the relativistic jet-launching mechanism is dominated by the blandford-znajek process. this result confirms previous findings. (3) there is a significant anticorrelation between jet magnetization and a ratio of the (sed) jet power to the (extended) kinetic jet power, which, for the first time, provides supporting evidence for the jet energy transportation theory: a high-magnetization jet may more easily transport energy to a large scale than a low-magnetization jet. | on the jet properties of γ-ray-loud active galactic nuclei |
we present predictions for the high-redshift halo-galaxy-supermassive black hole (smbh) connection from the trinity model. constrained by a comprehensive compilation of galaxy ($0\leq z \leq 10$) and smbh datasets ($0\leq z \leq 6.5$), trinity finds: 1) the number of smbhs with $m_\bullet > 10^9 m_\odot$ in the observable universe increases by six orders of magnitude from $z\sim10$ to $z\sim2$, and by another factor of $\sim 3$ from $z\sim2$ to $z=0$; 2) the $m_\bullet > 10^9/10^{10} m_\odot$ smbhs at $z\sim 6$ live in haloes with $\sim (2-3)/(3-5) \times 10^{12} m_\odot$; 3) the new jwst agns at $7\lesssim z \lesssim 11$ are broadly consistent with the median smbh mass-galaxy mass relation for agns from trinity; 4) seeds from runaway mergers in nuclear star clusters are viable progenitors for the smbhs in gn-z11 ($z=10.6$) and ceers_1019 ($z=8.7$); 5) $z=6-10$ quasar luminosity functions from wide area surveys by, e.g., roman and euclid, will reduce uncertainties in the $z=6-10$ smbh mass-galaxy mass relation by up to $\sim 0.5$ dex. | trinity iv: predictions for supermassive black holes at $z \\gtrsim 7$ |
we investigate the black hole mass function (bhmf) and eddington ratio distribution function (erdf) of broad-line agns at z=4, based on a sample of 52 quasars with i<23.2 at 3.50 < z < 4.25 from the hyper suprime-cam subaru strategic program (hsc-ssp) s16a-wide2 dataset, and 1,462 quasars with i<20.2 in the same redshift range from the sloan digital sky survey (sdss) dr7 quasar catalog. virial bh masses of quasars are estimated using the width of the civ 1549å line and the continuum luminosity at 1350å. to obtain the intrinsic broad-line agn bhmf and erdf, we correct for the incompleteness in the low-mass and/or low-eddington-ratio ranges caused by the flux-limited selection. the resulting bhmf is constrained down to $\log m_{\rm bh}/m_{\odot}\sim7.5$. in comparison with broad-line agn bhmfs at z=2 in the literature, we find that the number density of massive smbhs peaks at higher redshifts, consistent with the "down-sizing" evolutionary scenario. additionally, the resulting erdf shows a negative dependence on bh mass, suggesting more massive smbhs tend to accrete at lower eddington ratios at z=4. with the derived intrinsic broad-line agn bhmf, we also evaluate the active fraction of broad-line agns among the entire smbh population at z=4. the resulting active fraction may suggest a positive dependence on bh mass. finally, we examine the time evolution of broad-line agn bhmf between z=4 and 6 through solving the continuity equation. the results suggest that the broad-line agn bhmfs at z=4-6 only show evolution in their normalization, but with no significant changes in their shape. | black hole mass and eddington ratio distributions of less-luminous quasars at $z\\sim4$ in the subaru hyper suprime-cam wide field |
dense gas in minihalos (mhs) with masses of $10^6-10^8~m_\odot$ can shield themselves from reionization for about $100$ megayears after being exposed to uv radiation. these self-shielded systems, often unresolved in cosmological simulations, can introduce strong absorption in quasar spectra. this paper is the first systematic study on the impact of these systems on the ly$\alpha$ forest. we first derive the hi column density profile of photoevaporating mhs by conducting 1-dimensional radiation-hydrodynamics simulations. we utilize these results to estimate the ly$\alpha$ opacity from minihalos in a large-scale simulation that cannot resolve the self-shielding process. when the ionization rate of the background radiation is $0.03\times 10^{-12}~{\rm s}^{-1}$, as expected near the end of reionization at $z\sim 5.5$, we find that the incidence rate of damped ly$\alpha$ absorbers, $dn/dx$, increases by nearly a factor of 2 - 4 compared to at $z=4.5$. the ly$\alpha$ flux is, on average, suppressed by $10\%$ of its mean due to absorption by mhs. the extended absorption features contribute to a $\sim 20\%$ enhancement in the 1d power spectrum at $k\sim 0.1~h~{\rm mpc}^{-1}$ ($10^{-3}~{\rm km}^{-1}~{\rm s}$), which is comparable to the enhancement caused by inhomogeneous reionization. notably, the flux is particularly suppressed in the vicinity of large halos along the line-of-sight direction at separations of up to $10~h^{-1}~{\rm mpc}$ at $r_\perp\lesssim 2~h^{-1}~{\rm mpc}$. however, these effects become much smaller for higher ionizing rates ($0.3$ and $1\times 10^{-12}~{\rm s}^{-1}$) expected in the post-reionization universe $z\lesssim5.5$. our findings highlight the need to consider the absorption by mhs when interpreting the ly$\alpha$ forest at $z\gtrsim5.5$. moreover, the sensitivity of this effect to the ionizing background intensity can be exploited to constrain the intensity itself. | impact of self-shielding minihalos on the ly$\\alpha$ forest at high redshift |
we present atacama large millimeter/submillimeter array (alma) observations of the [c ii] fine-structure line and the underlying far-infrared (fir) dust continuum emission in j1120+0641, the most distant quasar currently known (z=7.1). we also present observations targeting the co(2-1), co(7-6), and [c i] 369 μm lines in the same source obtained at the very large array and plateau de bure interferometer. we find a [c ii] line flux of {f}[{{c}{{ii}}]}=1.11+/- 0.10 jy {km} {{{s}}}-1 and a continuum flux density of {s}227{ghz}=0.53+/- 0.04 mjy beam-1, consistent with previous unresolved measurements. no other source is detected in continuum or [c ii] emission in the field covered by alma (∼ 25″). at the resolution of our alma observations (0.″23, or 1.2 kpc, a factor of ∼70 smaller beam area compared to previous measurements), we find that the majority of the emission is very compact: a high fraction (∼80%) of the total line and continuum flux is associated with a region 1-1.5 kpc in diameter. the remaining ∼20% of the emission is distributed over a larger area with radius ≲4 kpc. the [c ii] emission does not exhibit ordered motion on kiloparsec scales: applying the virial theorem yields an upper limit on the dynamical mass of the host galaxy of (4.3+/- 0.9)× {10}10 {m}⊙ , only ∼20 × higher than the central black hole (bh). the other targeted lines (co(2-1), co(7-6), and [c i]) are not detected, but the limits of the line ratios with respect to the [c ii] emission imply that the heating in the quasar host is dominated by star formation, and not by the accreting bh. the star formation rate (sfr) implied by the fir continuum is 105-340 {m}⊙{{yr}}-1, with a resulting sfr surface density of ∼100-350 {m}⊙{{yr}}-1 kpc-2, well below the value for eddington-accretion-limited star formation. | the compact, ∼1 kpc host galaxy of a quasar at a redshift of 7.1 |
many black holes detected by the laser interferometer gravitational-wave observatory (ligo) and the virgo detectors are multiple times more massive than those in x-ray binaries. one possibility is that some binary black holes (bbhs) merge within a few schwarzschild radii of a supermassive black hole (smbh), so that the gravitational waves (gws) are highly redshifted, causing the mass inferred from gw signals to appear higher than the real mass. the difficulty of this scenario lies in the delivery of bbh to such a small distance to a smbh. here we revisit the theoretical models for the migration of compact objects (cos) in the accretion discs of active galactic nuclei (agns). we find that when the accretion rate is high so that the disc is best described by the slim disc model, the cos in the disc could migrate to a radius close to the innermost stable circular orbit and be trapped there for the remaining lifetime of the agn. the exact trapping radius coincides with the transition region between the sub- and super-keplerian rotation of the slim disc. we call this region 'the last migration trap' because further inward, cos can no longer be trapped for a long time. we pinpoint the parameter space that could induce such a trap and we estimate that the last migration trap contributes a few per cent of the ligo/virgo events. our result implies that a couple of bbhs discovered by ligo/virgo so far could have smaller intrinsic masses. | the last migration trap of compact objects in agn accretion disc |
disks of gas accreting onto supermassive black holes are thought to power active galactic nuclei (agn). stars may form in gravitationally unstable regions of these disks, or may be captured from nuclear star clusters. because of the dense gas environment, the evolution of these embedded stars can diverge dramatically from those in the interstellar medium. this work extends previous studies of stellar evolution in agn disks by exploring a variety of ways in which accretion onto stars in agn disks may differ from bondi accretion. we find that tidal effects from the supermassive black hole significantly alter the evolution of stars in agn disks, and that our results do not depend critically on assumptions about radiative feedback on the accretion stream. thus, in addition to depending on the ambient density and sound speed, the fate of stars in agn disks depends sensitively on the distance to and mass of the supermassive black hole. this affects the location in the disk in which stellar explosions occur, where compact remnants form and potentially merge to produce gravitational waves, and where different types of chemical enrichment take place. | accretion onto stars in the disks of active galactic nuclei |
we explore the potential of using the low-redshift lyman-$\alpha$ (ly$\alpha$) forest surrounding luminous red galaxies (lrgs) as a tool to constrain active galactic nuclei (agn) feedback models. our analysis is based on snapshots from the illustris and illustristng simulations at a redshift of $z=0.1$. these simulations offer an ideal platform for studying the influence of agn feedback on the gas surrounding galaxies, as they share the same initial conditions and underlying code but incorporate different feedback prescriptions. both simulations show significant impacts of feedback on the temperature and density of the gas around massive halos. following our previous work, we adjusted the uv background in both simulations to align with the observed number density of ly$\alpha$ lines ($\rm dn/dz$) in the intergalactic medium and study the ly$\alpha$ forest around massive halos hosting lrgs, at impact parameters ($r_{\perp}$) ranging from 0.1 to 100 pmpc. our findings reveal that $\rm dn/dz$, as a function of $r_{\perp}$, is approximately 1.5 to 2 times higher in illustristng compared to illustris up to $r_{\perp}$ of $\sim 10$ pmpc. to further assess whether existing data can effectively discern these differences, we search for archival data containing spectra of background quasars probing foreground lrgs. through a feasibility analysis based on this data, we demonstrate that ${\rm dn/dz} (r_{\perp})$ measurements can distinguish between feedback models of illustristng and illustris with a precision exceeding 12$\sigma$. this underscores the potential of ${\rm dn/dz} (r_{\perp})$ measurements around lrgs as a valuable benchmark observation for discriminating between different feedback models. | searching for the imprints of agn feedback on the lyman alpha forest around luminous red galaxies |
we present new chandra x-ray observatory and hubble space telescope observations of eight optically selected broad-line active galactic nucleus (agn) candidates in nearby dwarf galaxies (z < 0.055). including archival chandra observations of three additional sources, our sample contains all 10 galaxies from reines et al. (2013) with both broad hα emission and narrow-line agn ratios (six agns, four composites), as well as one low-metallicity dwarf galaxy with broad hα and narrow-line ratios characteristic of star formation. all 11 galaxies are detected in x-rays. nuclear x-ray luminosities range from l 0.5-7kev ≈ 5 × 1039 to 1 × 1042 ergs-1. in all cases except for the star-forming galaxy, the nuclear x-ray luminosities are significantly higher than would be expected from x-ray binaries, providing strong confirmation that agns and composite dwarf galaxies do indeed host actively accreting black holes (bhs). using our estimated bh masses (which range from ∼7 × 104 to 1 × 106 m ⊙), we find inferred eddington fractions ranging from ∼0.1% to 50%, i.e., comparable to massive broad-line quasars at higher redshift. we use the hst imaging to determine the ratio of uv to x-ray emission for these agns, finding that they appear to be less x-ray luminous with respect to their uv emission than more massive quasars (i.e., α ox values an average of 0.36 lower than expected based on the relation between α ox and 2500 å luminosity). finally, we discuss our results in the context of different accretion models onto nuclear bhs. | x-ray and ultraviolet properties of agns in nearby dwarf galaxies |
we study the influence of a high baryonic streaming velocity on the formation of direct collapse black holes (dcbhs) with the help of cosmological simulations carried out using the moving mesh code arepo. we show that a streaming velocity that is as large as three times the root-mean-squared value is effective at suppressing the formation of h2-cooled minihaloes, while still allowing larger atomic cooling haloes (achs) to form. we find that enough h2 forms in the centre of these achs to effectively cool the gas, demonstrating that a high streaming velocity by itself cannot produce the conditions required for dcbh formation. however, we argue that high streaming velocity regions do provide an ideal environment for the formation of dcbhs in close pairs of achs (the `synchronized halo' model). due to the absence of star formation in minihaloes, the gas remains chemically pristine until the achs form. if two such haloes form with only a small separation in time and space, then the one forming stars earlier can provide enough ultraviolet radiation to suppress h2 cooling in the other, allowing it to collapse to form a dcbh. baryonic streaming may therefore play a crucial role in the formation of the seeds of the highest redshift quasars. | the formation of direct collapse black holes under the influence of streaming velocities |
the first stars were born from chemically pristine gas. they were likely massive, and thus they rapidly exploded as supernovae, enriching the surrounding gas with the first heavy elements. in the local group, the chemical signatures of the first stellar population were identified among low-mass, long-lived, very metal-poor ([fe/h] < -2) stars, characterized by high abundances of carbon over iron ([c/fe] > +0.7): the so-called carbon-enhanced metal-poor stars. conversely, a similar carbon excess caused by first-star pollution was not found in dense neutral gas traced by absorption systems at different cosmic time. here we present the detection of 14 very metal-poor, optically thick absorbers at redshift z ~ 3-4. among these, 3 are carbon-enhanced and reveal an overabundance with respect to fe of all the analyzed chemical elements (o, mg, al, and si). their relative abundances show a distribution with respect to [fe/h] that is in very good agreement with those observed in nearby very metal-poor stars. all the tests we performed support the idea that these c-rich absorbers preserve the chemical yields of the first stars. our new findings suggest that the first-star signatures can survive in optically thick but relatively diffuse absorbers, which are not sufficiently dense to sustain star formation and hence are not dominated by the chemical products of normal stars. | evidence of first stars-enriched gas in high-redshift absorbers |
the bright blazar oj 287 routinely parades high brightness bremsstrahlung flares, which are explained as being a result of a secondary supermassive black hole (smbh) impacting the accretion disc of a more massive primary smbh in a binary system. the accretion disc is not rigid but rather bends in a calculable way due to the tidal influence of the secondary. next, we refer to this phenomenon as a variable disc level. we begin by showing that these flares occur at times predicted by a simple analytical formula, based on general relativity inspired modified kepler equation, which explains impact flares since 1888. the 2022 impact flare, namely flare number 26, is rather peculiar as it breaks the typical pattern of two impact flares per 12-yr cycle. this is the third bremsstrahlung flare of the current cycle that follows the already observed 2015 and 2019 impact flares from oj 287. it turns out that the arrival epoch of flare number 26 is sensitive to the level of primary smbh's accretion disc relative to its mean level in our model. we incorporate these tidally induced changes in the level of the accretion disc to infer that the thermal flare should have occurred during 2022 july-august, when it was not possible to observe it from the earth. thereafter, we explore possible observational evidence for certain pre-flare activity by employing spectral and polarimetric data from our campaigns in 2004/05 and 2021/22. we point out theoretical and observational implications of two observed mini-flares during 2022 january-february. | refining the oj 287 2022 impact flare arrival epoch |
the correlation between the broad line region radius and continuum luminosity (r-l relation) of active galactic nuclei (agns) is critical for single-epoch mass estimates of supermassive black holes (smbhs). at z ~ 1-2, where agn activity peaks, the r-l relation is constrained by the reverberation mapping (rm) lags of the mg ii line. we present 25 mg ii lags from the australian dark energy survey rm project based on 6 yr of monitoring. we define quantitative criteria to select good lag measurements and verify their reliability with simulations based on both the damped random walk stochastic model and the rescaled, resampled versions of the observed light curves of local, well-measured agn. our sample significantly increases the number of mg ii lags and extends the r-l relation to higher redshifts and luminosities. the relative iron line strength $\mathcal {r}_{\rm fe}$ has little impact on the r-l relation. the best-fitting mg iir-l relation has a slope α = 0.39 ± 0.08 with an intrinsic scatter $\sigma _{\rm rl} = 0.15^{+0.03}_{-0.02}$ . the slope is consistent with previous measurements and shallower than the h β r-l relation. the intrinsic scatter of the new r-l relation is substantially smaller than previous studies and comparable to the intrinsic scatter of the h β r-l relation. our new r-l relation will enable more precise single-epoch mass estimates and smbh demographic studies at cosmic noon. | ozdes reverberation mapping programme: mg ii lags and r-l relation |
we present, for the first time, dark matter halo (dmh) mass measurement of quasars at z ~ 6 based on a clustering analysis of 107 quasars. spectroscopically identified quasars are homogeneously extracted from the hyper suprime-cam strategic survey program wide layer over 891 deg2. we evaluate the clustering strength by three different autocorrelation functions: projected correlation function, angular correlation function, and redshift-space correlation function. the dmh mass of quasars at z ~ 6 is evaluated as ${5.0}_{-4.0}^{+7.4}\times {10}^{12}\,{h}^{-1}{m}_{\odot }$ with the bias parameter b = 20.8 ± 8.7 by the projected correlation function. the other two estimators agree with these values; though, each uncertainty is large. the dmh mass of quasars is found to be nearly constant ~1012.5 h -1 m ⊙ throughout cosmic time, suggesting that there is a characteristic dmh mass where quasars are always activated. as a result, quasars appear in the most massive halos at z ~ 6, but in less extreme halos thereafter. the dmh mass does not appear to exceed the upper limit of 1013 h -1 m ⊙, which suggests that most quasars reside in dmhs with ${m}_{\mathrm{halo}}\lt {10}^{13}{h}^{-1}{m}_{\odot }$ across most of the cosmic time. our results supporting a significant increasing bias with redshift are consistent with the bias evolution model with inefficient active galactic nucleus feedback at z ~ 6. the duty cycle (f duty) is estimated as 0.019 ± 0.008 by assuming that dmhs in some mass interval can host a quasar. the average stellar mass is evaluated from stellar-to-halo mass ratio as ${m}_{* }={6.5}_{-5.2}^{+9.6}\times {10}^{10}\,{h}^{-1}{m}_{\odot }$ , which is found to be consistent with [c ii] observational results. | subaru high-z exploration of low-luminosity quasars (shellqs). xviii. the dark matter halo mass of quasars at z 6 |
a new, complete sample of 14,584 broad-line active galactic nuclei (agns) at z < 0.35 is presented, which are uncovered homogeneously from the complete database of galaxies and quasars observed spectroscopically in the sloan digital sky survey seventh data release. the stellar continuum is properly removed for each spectrum with significant host absorption line features, and careful analyses of the emission line spectra, particularly in the hα and hβ wavebands, are carried out. the broad balmer emission line, particularly hα, is used to indicate the presence of an agn. the broad hα lines have luminosities in a range of 1038.5- 1044.3 {erg} {{{s}}}-1, and line widths (fwhms) of 500-34,000 {km} {{{s}}}-1. the virial black hole masses, estimated from the broad-line measurements, span a range of 105.1- 1010.3 {m}⊙ , and the eddington ratios vary from -3.3 to 1.3 in logarithmic scale. other quantities such as multiwavelength photometric properties and flags denoting peculiar line profiles are also included in this catalog. we describe the construction of this catalog and briefly discuss its properties. the catalog is publicly available online. this homogeneously selected agn catalog, along with the accurately measured spectral parameters, provides the most updated, largest agn sample data, which will enable further comprehensive investigations of the properties of the agn population in the low-redshift universe. | a comprehensive and uniform sample of broad-line active galactic nuclei from the sdss dr7 |
compressing large data sets to a manageable number of summaries that are informative about the underlying parameters vastly simplifies both frequentist and bayesian inference. when only simulations are available, these summaries are typically chosen heuristically, so they may inadvertently miss important information. we introduce a simulation-based machine learning technique that trains artificial neural networks to find nonlinear functionals of data that maximize fisher information: information maximizing neural networks (imnns). in test cases where the posterior can be derived exactly, likelihood-free inference based on automatically derived imnn summaries produces nearly exact posteriors, showing that these summaries are good approximations to sufficient statistics. in a series of numerical examples of increasing complexity and astrophysical relevance we show that imnns are robustly capable of automatically finding optimal, nonlinear summaries of the data even in cases where linear compression fails: inferring the variance of gaussian signal in the presence of noise, inferring cosmological parameters from mock simulations of the lyman-α forest in quasar spectra, and inferring frequency-domain parameters from lisa-like detections of gravitational waveforms. in this final case, the imnn summary outperforms linear data compression by avoiding the introduction of spurious likelihood maxima. we anticipate that the automatic physical inference method described in this paper will be essential to obtain both accurate and precise cosmological parameter estimates from complex and large astronomical data sets, including those from lsst and euclid. | automatic physical inference with information maximizing neural networks |
we present a study of the metal-enriched halo gas, traced using mg ii and [o ii] emission lines, in two large, blind galaxy surveys - the muse (multi unit spectroscopic explorer) analysis of gas around galaxies (magg) and the muse ultra deep field (mudf). by stacking a sample of ≈600 galaxies (stellar masses $m_*$ ≈ 106-12 $\rm m_\odot$), we characterize for the first time the average metal line emission from a general population of galaxy haloes at 0.7 ≤ z ≤ 1.5. the mg ii and [o ii] line emission extends farther out than the stellar continuum emission, on average out to ≈25 and ≈45 kpc, respectively, at a surface brightness (sb) level of 10-20 $\rm erg\, s^{-1}\, cm^{-2}\, arcsec^{-2}$. the radial profile of the mg ii sb is shallower than that of the [o ii], suggesting that the resonant mg ii emission is affected by dust and radiative transfer effects. the [o ii] to mg ii sb ratio is ≈3 over ≈20-40 kpc, also indicating a significant in situ origin of the extended metal emission. the average sb profiles are intrinsically brighter by a factor of ≈2-3 and more radially extended by a factor of ≈1.3 at 1.0 < z ≤ 1.5 than at 0.7 ≤ z ≤ 1.0. the average extent of the metal emission also increases independently with increasing stellar mass and in overdense group environments. when considering individual detections, we find extended [o ii] emission up to ≈50 kpc around ≈30-40 per cent of the group galaxies, and extended (≈30-40 kpc) mg ii emission around two z ≈ 1 quasars in groups, which could arise from outflows or environmental processes. | metal line emission from galaxy haloes at z ≈ 1 |
although the hubble constant h0 and spatial curvature ωk have been measured with very high precision, they still suffer from some tensions. in this paper, we propose an improved method to combine the observations of ultracompact structure in radio quasars and strong gravitational lensing with quasars acting as background sources to determine h0 and ωk simultaneously. by applying the distance sum rule to the time-delay measurements of seven strong lensing systems and 120 intermediate-luminosity quasars calibrated as standard rulers, we obtain stringent constraints on the hubble constant (h0 = 78.3 ± 2.9 km s-1 mpc-1) and the cosmic curvature (ωk = 0.49 ± 0.24). on the one hand, in the framework of a flat universe, the measured hubble constant ( $h_0=73.6^{+1.8}_{-1.6} \mathrm{\,km\,s^{-1}\,mpc^{-1}}$ ) is strongly consistent with that derived from the local distance ladder, with a precision of 2 per cent. on the other hand, if we use the local h0 measurement as a prior, our results are marginally compatible with zero spatial curvature ( $\omega _k=0.23^{+0.15}_{-0.17}$ ) and there is no significant deviation from a flat universe. finally, we also evaluate whether strongly lensed quasars would produce robust constraints on h0 and ωk in the non-flat and flat λ cold dark matter model, if the compact radio structure measurements are available from very long baseline interferometry observations. | measurements of the hubble constant and cosmic curvature with quasars: ultracompact radio structure and strong gravitational lensing |
we present a study of the relation between x-rays and ultraviolet emission in quasars for a sample of broad-line, radio-quiet objects obtained from the cross-match of the sloan digital sky survey dr14 with the latest chandra source catalog 2.0 (2332 quasars) and the chandra cosmos legacy survey (273 quasars). the non-linear relation between the ultraviolet (at 2500 å, luv) and the x-ray (at 2 kev, lx) emission in quasars has been proved to be characterised by a smaller intrinsic dispersion than the observed one, as long as a homogeneous selection, aimed at preventing the inclusion of contaminants in the sample, is fulfilled. by leveraging on the low background of chandra, we performed a complete spectral analysis of all the data available for the sdss-csc2.0 quasar sample (i.e. 3430 x-ray observations), with the main goal of reducing the uncertainties on the source properties (e.g. flux, spectral slope). we analysed whether any evolution of the lx − luv relation exists by dividing the sample in narrow redshift intervals across the redshift range spanned by our sample, z ≃ 0.5−4. we find that the slope of the relation does not evolve with redshift and it is consistent with the literature value of 0.6 over the explored redshift range, implying that the mechanism underlying the coupling of the accretion disc and hot corona is the same at the different cosmic epochs. we also find that the dispersion decreases when examining the highest redshifts, where only pointed observations are available. these results further confirm that quasars are `standardisable candles', that is we can reliably measure cosmological distances at high redshifts where very few cosmological probes are available. full table 2 is 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/655/a109 | the chandra view of the relation between x-ray and uv emission in quasars |
quasar-driven outflows must have made their most significant impact on galaxy formation during the epoch when massive galaxies were forming most rapidly. to study the impact of quasar feedback, we conducted rest-frame optical integral field spectrograph (ifs) observations of three extremely red quasars (erqs) and one type-2 quasar at z = 2-3, obtained with the nifs and osiris instruments at the gemini north and w. m. keck observatory with the assistance of laser-guided adaptive optics. we use the kinematics and morphologies of the [o iii] 5007 å and h α 6563 å emission lines redshifted into the near-infrared to gauge the extents, kinetic energies and momentum fluxes of the ionized outflows in the quasars host galaxies. for the erqs, the galactic-scale outflows are likely driven by radiation pressure in a high column density environment or due to an adiabatic shock. the outflows in the erqs carry a significant amount of energy ranging from 0.05 to 5 ${{\ \rm per\ cent}}$ of the quasar's bolometric luminosity, powerful enough to have a significant impact on the quasar host galaxies. the outflows are resolved on kpc scales, the observed outflow sizes are generally smaller than other ionized outflows observed at high redshift. the high ratio between the momentum flux of the ionized outflow and the photon momentum flux from the quasar accretion disc and high nuclear obscuration makes these erqs great candidates for transitional objects where the outflows are likely responsible for clearing material in the inner regions of each galaxy, unveiling the quasar accretion disc at optical wavelengths. | powerful winds in high-redshift obscured and red quasars |
we study axion strings of hyperlight axions coupled to photons. hyperlight axions — axions lighter than hubble at recombination — are a generic prediction of the string axiverse. these axions strings produce a distinct quantized polarization rotation of cmb photons which is o (αem). as the cmb light passes many strings, this polarization rotation converts e-modes to b-modes and adds up like a random walk. using numerical simulations we show that the expected size of the final result is well within the reach of current and future cmb experiments through the measurement of correlations of cmb b-modes with e- and t-modes. the quantized polarization rotation angle is topological in nature and can be seen as a geometric phase. its value depends only on the anomaly coefficient and is independent of other details such as the axion decay constant. measurement of the anomaly coefficient by measuring this rotation will provide information about the uv theory, such as the quantization of electric charge and the value of the fundamental unit of charge. the presence of axion strings in the universe relies only on a phase transition in the early universe after inflation, after which the string network rapidly approaches an attractor scaling solution. if there are additional stable topological objects such as domain walls, axions as heavy as 10-15 ev would be accessible. the existence of these strings could also be probed by measuring the relative polarization rotation angle between different images in gravitationally lensed quasar systems. | a cmb millikan experiment with cosmic axiverse strings |
we report the results of james webb space telescope/nircam observations of 19 (sub)millimeter sources detected by the atacama large millimeter array (alma). the accurate alma positions allowed unambiguous identifications of their nircam counterparts. taking gravitational lensing into account, these represent 16 distinct galaxies in three fields and constitute the largest sample of its kind to date. the counterparts' spectral energy distributions cover from rest-frame ultraviolet to near-ir and provide photometric redshifts (1 < z < 4.5) and stellar masses (m * > 1010.5 m ⊙), which are similar to submillimeter galaxies (smgs) studied previously. however, our sample is fainter in (sub)millimeter than the classic smg samples are, and our sources exhibit a wider range of properties. they have dust-embedded star formation rates as low as 10 m ⊙ yr-1, and the sources populate both the star-forming main sequence and the quiescent categories. the deep nircam data allow us to study the rest-frame near-ir morphologies. excluding two multiply imaged systems and one quasar, the majority of the remaining sources are disk-like and show either little or no disturbance. this suggests that secular growth is a potential route for the assembly of high-mass disk galaxies. while a few objects have large disks, the majority have small disks (median half-mass radius of 1.6 kpc). at this time, it is unclear whether this is due to the prevalence of small disks at these redshifts or some unknown selection effects of deep alma observations. a larger sample of alma sources with nircam observations will be able to address this question. | jwst's pearls: a jwst/nircam view of alma sources |
we construct cosmic void catalogues with the dive void finder upon sdss boss dr12 and eboss dr16 galaxy samples with bao reconstruction, and perform a joint bao analysis using different types of galaxies and the corresponding voids. the bao peak is evident for the galaxy-galaxy, galaxy-void, and void-void correlation functions of all data sets, including the ones cross-correlating lrg and elg samples. two multitracer bao fitting schemes are tested, one combining the galaxy and void correlation functions with a weight applied to voids, and the other using a single bao dilation parameter for all clustering measurements. both methods produce consistent results with mock catalogues, and on average ~10 per cent improvements of the bao statistical uncertainties are observed for all samples, compared to the results from galaxies alone. by combining the clustering of galaxies and voids, the uncertainties of bao measurements from the sdss data are reduced by 5-15 per cent, yielding 0.9 per cent, 0.8 per cent, 1.1 per cent, 2.3 per cent, and 2.9 per cent constraints on the distance $d_{_{\rm v}}(z)$, at effective redshifts 0.38, 0.51, 0.70, 0.77, and 0.85, respectively. when combined with bao measurements from sdss mgs, qso, and lyα samples, as well as the bbn results, we obtain $h_0 = 67.58 \pm 0.91\, {\rm km}\, {\rm s}^{-1}\, {\rm mpc}^{-1}$, ωm = 0.290 ± 0.015, and $\omega _\lambda h^2 = 0.3241 \pm 0.0079$ in the flat-λcdm framework, where the 1σ uncertainties are around 6 per cent, 6 per cent, and 17 per cent smaller respectively, compared to constraints from the corresponding anisotropic bao measurements without voids and lrg-elg cross-correlations. | the completed sdss-iv extended baryon oscillation spectroscopic survey: cosmological implications from multitracer bao analysis with galaxies and voids |
massive black holes in the centres of galaxies today must have grown by several orders of magnitude from seed black holes formed at early times. detecting a population of intermediate mass black holes (imbhs) can provide constraints on these elusive bh seeds. here, we use the large volume cosmological hydrodynamical simulation astrid, which includes imbh seeds and dynamical friction to investigate the population of imbh seeds. dynamical friction is largely inefficient at sinking and merging seed imbhs at high-z. this leads to an extensive population (several hundred per galaxy) of wandering imbhs in large haloes at $z\sim 2$. a small fraction of these imbhs are detectable as hlxs, hyper luminous x-ray sources. importantly, at $z\sim 2$, imbhs mergers produce the peak of gw events. we find close to a million gw events in astrid between $z=\rm{2\!-\!3}$ involving seed imbh mergers. these gw events (almost all detectable by lisa) at cosmic noon should provide strong constraints on imbh seed models and their formation mechanisms. at the centre of massive galaxies, where the number of imbhs can be as high as 10-100, smbh-imbh pairs can form. these intermediate mass ratio inspirals (imris) and extreme mass ratio inspirals (emris), will require the next generation of milli-$\mu$hz space-based gw interferometers to be detected. large populations of imbhs around massive black holes will probe their environments and mbh causal structure. | a vast population of wandering and merging imbhs at cosmic noon |
we use 118 hβ quasar (qso) observations in the redshift range 0.0023 ≤ z ≤ 0.89 to simultaneously constrain cosmological model parameters and qso 2-parameter radius-luminosity (r-l) relation parameters in six different cosmological models. we find that the r-l relation parameters for these qsos are independent of the assumed cosmology so these qsos seem to be standardizable through the r-l relation (although there is a complication that might render this untrue). cosmological constraints obtained using these qsos are weak, more favour currently decelerated cosmological expansion, and typically are in ~2σ tension with those obtained from a joint analysis of baryon acoustic oscillation and hubble parameter measurements. extending the r-l relation to a 3-parameter one to try to correct for the accretion rate effect does not result in a reduction of the cosmological constraints discrepancy nor does it result in the hoped-for significant reduction of the intrinsic scatter of the r-l relation. | do reverberation-measured hβ quasars provide a useful test of cosmology? |
we present the first polarimetric space very long baseline interferometry (vlbi) observations of oj 287, observed with radioastron at 22 ghz during a perigee session on 2014 april 4 and five near-in-time snapshots, together with contemporaneous ground vlbi observations at 15, 43, and 86 ghz. ground-space fringes were obtained up to a projected baseline of 3.9 earth diameters during the perigee session, and at a record 15.1 earth diameters during the snapshot sessions, allowing us to image the innermost jet at an angular resolution of ~50μ as, the highest ever achieved at 22 ghz for oj 287. comparison with ground-based vlbi observations reveals a progressive jet bending with increasing angular resolution that agrees with predictions from a supermassive binary black hole model, although other models cannot be ruled out. spectral analyses suggest that the vlbi core is dominated by the internal energy of the emitting particles during the onset of a multiwavelength flare, while the parsec-scale jet is consistent with being in equipartition between the particles and magnetic field. estimated minimum brightness temperatures from the visibility amplitudes show a continued rising trend with projected baseline length up to 1013 k, reconciled with the inverse-compton limit through doppler boosting for a jet closely oriented to the line of sight. the observed electric vector position angle suggests that the innermost jet has a predominantly toroidal magnetic field, which, together with marginal evidence of a gradient in rotation measure across the jet width, indicates that the vlbi core is threaded by a helical magnetic field, in agreement with jet formation models. | probing the innermost regions of agn jets and their magnetic fields with radioastron. v. space and ground millimeter-vlbi imaging of oj 287 |
context. quasi-periodic x-ray eruptions (qpes) are a recently discovered phenomenon, the nature of which remains unclear. based on their discovery in active galactic nuclei (agns), explanations related to an agn accretion disk or potentially a stellar tidal disruption event (tde) have been put forward. alternatives, including highly unequal mass compact object binaries, have also been proposed to explain their properties.aims: we perform a systematic study of the five known qpe host galaxies with the aim of providing new insights as to their nature.methods: we analysed new and archival medium resolution optical spectroscopy of the qpe hosts. we measured emission (and absorption) line fluxes, their ratios, and equivalent widths (ews) to locate the qpe hosts on diagnostic diagrams. we also measured the velocity dispersion of the stellar absorption lines to estimate their black hole masses.results: all qpe host galaxies show emission lines in their optical spectra. based on their ratios and ews, we find evidence for the presence of an agn in all sources, including those previously reported as passive. we measure velocity dispersions between 36 and 90 km s−1, implying the presence of low mass (105−6.7 m⊙) black holes, consistent with literature findings. finally, we find a significant over-representation (two out of the five sources, or a factor of 13−10+13) of quiescent balmer strong (post-starburst) galaxies among qpe hosts.conclusions: the presence of a narrow line region consistent with an agn in all qpe host galaxies implies that a long-lived accretion flow likely plays an integral part in the qpe phenomenon. the strong over-representation of quiescent balmer strong galaxies among qpe hosts can be naturally explained in both the tde and interacting extreme mass ratio inspiral hypotheses. the host galaxy spectra 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/659/l2 | host galaxy properties of quasi-periodically erupting x-ray sources |
our motion through the universe generates a dipole in the temperature anisotropies of the cosmic microwave background (cmb) and also in the angular distribution of sources. if the cosmological principle is valid, these two dipoles are directly linked, such that the amplitude of one determines that of the other. however, it is a longstanding problem that number counts of radio sources and of quasars at low and intermediate redshifts exhibit a dipole that is well aligned with that of the cmb but with about twice the expected amplitude, leading to a tension reaching up to 4.9σ. in this paper, we revisit the theoretical derivation of the dipole in the sources number counts, explicitly accounting for the redshift evolution of the population of sources. we argue that if the spectral index and magnification bias of the sources vary with redshift, the standard theoretical description of the dipole may be inaccurate. we provide an alternative expression which does not depend on the spectral index, but instead on the time evolution of the population of sources. we then determine the values that this evolution rate should have in order to remove the tension with the cmb dipole. | on the kinematic cosmic dipole tension |
the detection of lyα nebulae around z ≳ 6 quasars reveals extended gas reservoirs around the first rapidly growing supermassive black holes. observations of z > 6 quasars can be explained by cosmological models provided that the black holes by which they are powered evolve in rare, massive dark matter haloes. whether these models also explain the observed extended lyα emission remains an open question. we post-process a suite of cosmological, radiation-hydrodynamic simulations, targeting a quasar host halo at z > 6 with the lyα radiative transfer code rascas. a combination of recombination radiation from photo-ionized hydrogen and emission from collisionally excited gas powers lyα nebulae with a surface brightness profile in a close agreement with observations. we also find that, even on its own, resonant scattering of the lyα line associated to the quasar's broad-line region can also generate lyα emission on $\sim 100 \, \rm kpc$ scales, resulting in comparable agreement with observed surface brightness profiles. even if powered by a broad quasar lyα line, lyα nebulae have narrow line-widths $\lesssim 1000 \, \rm km \, s^{-1}$, consistent with observational constraints. even if there is no quasar, we find that halo gas cooling produces a faint, extended lyα glow. however, to explain the brightest lyα nebulae, our simulations unambiguously require quasar-powered outflows to clear out the galactic nucleus and allow the lyα flux to escape and still remain resonant with halo gas. the close match between observations and simulations with quasar outflows suggest that agn feedback already operates before $z \, = \, 6$ and confirms that high-z quasars reside in massive haloes tracing overdensities. | agn-driven outflows and the formation of lyα nebulae around high-z quasars |
we detect the cross-correlation between 2.7 million desi quasar targets across 14,700 deg$^2$ (180 quasars deg$^{-2}$) and planck 2018 cmb lensing at $\sim$30$\sigma$. we use the cross-correlation on very large scales to constrain local primordial non-gaussianity via the scale dependence of quasar bias. the desi quasar targets lie at an effective redshift of 1.51 and are separated into four imaging regions of varying depth and image quality. we select quasar targets from legacy survey dr9 imaging, apply additional flux and photometric redshift cuts to improve the purity and reduce the fraction of unclassified redshifts, and use early desi spectroscopy of 194,000 quasar targets to determine their redshift distribution and stellar contamination fraction (2.6%). due to significant excess large-scale power in the quasar autocorrelation, we apply weights to mitigate contamination from imaging systematics such as depth, extinction, and stellar density. we use realistic contaminated mocks to determine the greatest number of systematic modes that we can fit, before we are biased by overfitting and spuriously remove real power. we find that linear regression with one to seven imaging templates removed per region accurately recovers the input cross-power, $f_{\textrm{nl}}$ and linear bias. as in previous analyses, our $f_{\textrm{nl}}$ constraint depends on the linear primordial non-gaussianity bias parameter, $b_{\phi} = 2(b - p)\delta_c$ assuming universality of the halo mass function. we measure $f_{\textrm{nl}} = -26^{+45}_{-40}$ with $p=1.6$ $(f_{\textrm{nl}} = -18^{+29}_{-27}$ with $p=1.0$), and find that this result is robust under several systematics tests. future spectroscopic quasar cross-correlations with planck lensing lensing can tighten the $f_{\textrm{nl}}$ constraints by a factor of 2 if they can remove the excess power on large scales in the quasar auto power spectrum. | constraining primordial non-gaussianity from desi quasar targets and planck cmb lensing |
we consider the effect of including an active galactic nuclei (agn) component when fitting spectral energy distributions of 109 spectroscopically confirmed z ≈ 3.5-12.5 galaxies with jwst. remarkably, we find that the resulting cosmic star formation history is ≈0.4 dex lower at z ≳ 9.5 when an agn component is included in the fitting. this alleviates previously reported excess star formation at z ≳ 9.5 compared to models based on typical baryon conversion efficiencies inside dark matter halos. we find that the individual stellar masses and star formation rates can be as much as ≈4 dex lower when fitting with an agn component. these results highlight the importance of considering both stellar mass assembly and supermassive black hole growth when interpreting the light distributions of among the first galaxies to ever exist. | star formation and agn activity 500 myr after the big bang: insights from jwst |
context. the z ∼ 0.1 type-2 qso j1430+1339, known as the "teacup", is a complex galaxy showing a loop of ionised gas ∼10 kpc in diameter, co-spatial radio bubbles, a compact (∼1 kpc) jet, and outflow activity. its closeness offers the opportunity to study in detail the intricate interplay between the central supermassive black hole (smbh) and the material in and around the galaxy, both the interstellar medium (ism) and circumgalactic medium (cgm).aims: we characterise the spatially resolved properties and effects of the galactic ionised gas outflow and compare them with those of the radio jet and with theoretical predictions to infer its acceleration mechanism.methods: we used vlt/muse optical integral field spectroscopic observations to obtain flux, kinematic, and excitation maps of the extended (up to ∼100 kpc) ionised gas and to characterise the properties of stellar populations. we built radial profiles of the outflow properties as a function of distance from the active nucleus, from kiloparsec up to tens of kiloparsec scales, at ∼1 kpc resolution.results: we detect a velocity dispersion enhancement (≳300 km s−1) elongated over several kiloparsecs perpendicular to the radio jet, the active galactic nucleus (agn) ionisation lobes, and the fast outflow, similar to what is found in other galaxies hosting compact, low-power jets, indicating that the jet strongly perturbs the host ism during its passage. we observe a decreasing trend with distance from the nucleus for the outflow properties (mass outflow rate, kinetic rate, momentum rate). the mass outflow rate drops from around 100 m⊙ yr−1 in the inner 1-2 kpc to ≲0.1 m⊙ yr−1 at 30 kpc. the mass outflow rate of the ionised outflow is significantly higher (∼1-8 times) than the molecular one, in contrast with what is often quoted in agn. based on energetic and morphological arguments, the driver of the multi-phase outflow is likely a combination of agn radiation and the jet, or agn radiation pressure on dust alone. the outflow mass-loading factor is ∼5-10 and the molecular gas depletion time due to the multi-phase outflow is ≲108 yr, indicating that the outflow can significantly affect the star formation and the gas reservoir in the galaxy. however, the fraction of the ionised outflow that is able to escape the dark matter halo potential is likely negligible. we detect blue-coloured continuum emission co-spatial with the ionised gas loop. here, stellar populations are younger (≲100-150 myr) than in the rest of the galaxy (∼0.5-1 gyr). this constitutes possible evidence for star formation triggered at the edge of the bubble due to the compressing action of the jet and outflow ("positive feedback"), as predicted by theory. all in all, the teacup constitutes a rich system in which agn feedback from outflows and jets, in both its negative and positive flavours, co-exist. based on observations made with eso telescopes at the la silla paranal observatory under programme id 0102.b-0107. | complex agn feedback in the teacup galaxy. a powerful ionised galactic outflow, jet-ism interaction, and evidence for agn-triggered star formation in a giant bubble |
without active galactic nucleus (agn) feedback, simulated massive, star-forming galaxies become too compact relative to observed galaxies at z ≲ 2. in this paper, we perform high-resolution re-simulations of a massive ($m_{\star }\sim 10^{11}\, \rm {{\rm m}_{\odot }}$) galaxy at z ~ 2.3, drawn from the feedback in realistic environments (fire) project. in the simulation without agn feedback, the galaxy experiences a rapid starburst and shrinking of its half-mass radius. we experiment with driving mechanical agn winds, using a state-of-the-art hyper-lagrangian refinement technique to increase particle resolution. these winds reduce the gas surface density in the inner regions of the galaxy, suppressing the compact starburst and maintaining an approximately constant half-mass radius. using radiative transfer, we study the impact of agn feedback on the magnitude and extent of the multiwavelength continuum emission. when agn winds are included, the suppression of the compact, dusty starburst results in lowered flux at fir wavelengths (due to decreased star formation) but increased flux at optical-to-near-ir wavelengths (due to decreased dust attenuation, in spite of the lowered star formation rate), relative to the case without agn winds. the fir half-light radius decreases from ~1 to $\sim 0.1\, \rm {kpc}$ in $\lesssim 40\, \rm {myr}$ when agn winds are not included, but increases to $\sim 2\, \rm {kpc}$ when they are. interestingly, the half-light radius at optical-nir wavelengths remains approximately constant over $35\, \rm {myr}$, for simulations with and without agn winds. in the case without winds, this occurs despite the rapid compaction, and is due to heavy dust obscuration in the inner regions of the galaxy. this work highlights the importance of forward-modelling when comparing simulated and observed galaxy populations. | the impact of agn-driven winds on physical and observable galaxy sizes |
we present a reanalysis of reverberation mapping data from 2005 for the seyfert galaxy ngc 4151, supplemented with additional data from the literature to constrain the continuum variations over a significantly longer baseline than the original monitoring program. modeling of the continuum light curve and the velocity-resolved variations across the hβ emission line constrains the geometry and kinematics of the broad line region (blr). the blr is well described by a very thick disk with similar opening angle (θo≈ 57°) and inclination angle (θi≈ 58°), suggesting that our sight line toward the innermost central engine skims just above the surface of the blr. the inclination is consistent with constraints from geometric modeling of the narrow-line region, and the similarity between the inclination and opening angles is intriguing given previous studies of ngc 4151 that suggest blr gas has been observed temporarily eclipsing the x-ray source. the blr kinematics are dominated by eccentric bound orbits, with ~10% of the orbits preferring near-circular motions. with the blr geometry and kinematics constrained, the models provide an independent and direct black hole mass measurement of $\mathrm{log}{m}_{\mathrm{bh}}/{m}_{\odot }={7.22}_{-0.10}^{+0.11}$ or ${m}_{\mathrm{bh}}={1.66}_{-0.34}^{+0.48}\times {10}^{7}$ m ⊙, which is in good agreement with mass measurements from stellar dynamical modeling and gas dynamical modeling. ngc 4151 is one of the few nearby broad-lined seyferts where the black hole mass may be measured via multiple independent techniques, and it provides an important test case for investigating potential systematics that could affect the black hole mass scales used in the local universe and for high-redshift quasars. | the broad line region and black hole mass of ngc 4151 |
reverberation mapping is a robust method to measure the masses of supermassive black holes outside of the local universe. measurements of the radius-luminosity (r-l) relation using the mg ii emission line are critical for determining these masses near the peak of quasar activity at z ≈ 1-2, and for calibrating secondary mass estimators based on mg ii that can be applied to large samples with only single-epoch spectroscopy. we present the first nine mg ii lags from our 5-yr australian dark energy survey reverberation mapping programme, which substantially improves the number and quality of mg ii lag measurements. as the mg ii feature is somewhat blended with iron emission, we model and subtract both the continuum and iron contamination from the multiepoch spectra before analysing the mg ii line. we also develop a new method of quantifying correlated spectroscopic calibration errors based on our numerous, contemporaneous observations of f-stars. the lag measurements for seven of our nine sources are consistent with both the h β and mg ii r-l relations reported by previous studies. our simulations verify the lag reliability of our nine measurements, and we estimate that the median false positive rate of the lag measurements is $4{{\ \rm per\ cent}}$. | ozdes reverberation mapping programme: the first mg ii lags from 5 yr of monitoring |
the project momo (multiwavelength observations and modelling of oj 287) was set up to test predictions of binary supermassive black hole (smbh) scenarios and to understand disc-jet physics of the blazar oj 287. after a correction, the precessing binary (pb) smbh model predicted the next main outburst of oj 287 in 2022 october, making the outburst well observable and the model testable. we have densely covered this period in our ongoing multifrequency radio, optical, ultraviolet (uv), and x-ray monitoring. the predicted outburst was not detected. instead, oj 287 was at low optical-uv emission levels, declining further into november. the predicted thermal bremsstrahlung spectrum was not observed either, at any epoch. further, applying scaling relations, we estimate an smbh mass of oj 287 of 108 m⊙. the latest in a sequence of deep low states that recur every 1-2 yr is used to determine an upper limit on the eddington ratio and on the accretion-disc luminosity. this limit is at least a factor of 10 lower than required by the pb model with its massive primary smbh of >1010 m⊙. all these results favour alternative binary smbh models of oj 287 that require neither strong orbital precession nor a very large mass of the primary smbh. | absence of the predicted 2022 october outburst of oj 287 and implications for binary smbh scenarios |
this paper presents a survey of mg ii absorbing gas in the vicinity of 380 random galaxies, using 156 background quasi-stellar objects (qsos) as absorption-line probes. the sample comprises 211 isolated (73 quiescent and 138 star-forming galaxies) and 43 non-isolated galaxies with sensitive constraints for both mg ii absorption and h α emission. the projected distances span a range from d = 9 to 497 kpc, redshifts of the galaxies range from z = 0.10 to 0.48, and rest-frame absolute b-band magnitudes range from mb = -16.7 to -22.8. our analysis shows that the rest-frame equivalent width of mg ii, wr(2796), depends on halo radius (rh), b-band luminosity(lb), and stellar mass (mstar) of the host galaxies, and declines steeply with increasing d for isolated, star-forming galaxies. at the same time, wr(2796) exhibits no clear trend for either isolated, quiescent galaxies or non-isolated galaxies. in addition, the covering fraction of mg ii absorbing gas ⟨κ⟩ is high with ⟨κ⟩ ≳ 60 per cent at <40 kpc for isolated galaxies and declines rapidly to ⟨κ⟩ ≈ 0 at d ≳ 100 kpc. within the gaseous radius, the incidence of mg ii gas depends sensitively on both mstar and the specific star formation rate inferred from h α. different from what is known for massive quiescent haloes, the observed velocity dispersion of mg ii absorbing gas around star-forming galaxies is consistent with expectations from virial motion, which constrains individual clump mass to $m_{\rm cl} \gtrsim 10^5 \, \rm m_\odot$ and cool gas accretion rate of $\sim 0.7\!-\!2 \, \mathrm{ m}_\odot \, \rm yr^{-1}$. finally, we find no strong azimuthal dependence of mg ii absorption for either star-forming or quiescent galaxies. our results demonstrate that multiple parameters affect the properties of gaseous haloes around galaxies and highlight the need of a homogeneous, absorption-blind sample for establishing a holistic description of chemically enriched gas in the circumgalactic space. | a complete census of circumgalactic mg ii at redshift z ≲ 0.5 |
the observation of a very high-energy neutrino by icecube (icecube-170922a) and its association with the flaring blazar txs 0506 + 056 provided the first multimessenger observations of blazar jets, demonstrating the important role of protons in their dynamics and emission. in this paper, we present soprano (https://www.amsdc.am/soprano), a new conservative implicit kinetic code that follows the time evolution of the isotropic distribution functions of protons, neutrons, and the secondaries produced in photo-pion and photo-pair interactions, alongside with the evolution of photon and electron/positron distribution functions. soprano is designed to study leptonic and hadronic processes in relativistic sources such as blazars and gamma-ray bursts. here, we use soprano to model the broadband spectrum of txs 0506 + 056 and 3hsp j095507.9 + 355101, which are associated with neutrino events, and of the extreme flaring blazar 3c 279. the seds are interpreted within the guise of both a hadronic and a hybrid model. we discuss the implications of our assumptions in terms of jet power and neutrino flux. | time-dependent lepto-hadronic modelling of the emission from blazar jets with soprano: the case of txs 0506 + 056, 3hsp j095507.9 + 355101, and 3c 279 |
we present the z ≈ 6 type-1 quasar luminosity function (qlf), based on the pan-starrs1 (ps1) quasar survey. the ps1 sample includes 125 quasars at z ≈ 5.7-6.2, with -28 ≲ m 1450 ≲ -25. with the addition of 48 fainter quasars from the shellqs survey, we evaluate the z ≈ 6 qlf over -28 ≲ m 1450 ≲ -22. adopting a double power law with an exponential evolution of the quasar density (φ(z) ∝ 10 k(z-6); k = -0.7), we use a maximum likelihood method to model our data. we find a break magnitude of ${m}^{* }=-{26.38}_{-0.60}^{+0.79}\,\mathrm{mag}$ , a faint-end slope of $\alpha =-{1.70}_{-0.19}^{+0.29}$ , and a steep bright-end slope of $\beta =-{3.84}_{-1.21}^{+0.63}$ . based on our new qlf model, we determine the quasar comoving spatial density at z ≈ 6 to be $n({m}_{1450}\lt -26)={1.16}_{-0.12}^{+0.13}\,{\mathrm{cgpc}}^{-3}$ . in comparison with the literature, we find the quasar density to evolve with a constant value of k ≈ -0.7, from z ≈ 7 to z ≈ 4. additionally, we derive an ionizing emissivity of ${\epsilon }_{912}(z=6)={7.23}_{-1.02}^{+1.65}\times {10}^{22}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{hz}}^{-1}\,{\mathrm{cmpc}}^{-3}$ , based on the qlf measurement. given standard assumptions, and the recent measurement of the mean free path by becker et al. at z ≈ 6, we calculate an h i photoionizing rate of γh i(z = 6) ≈ 6 × 10-16 s-1, strongly disfavoring a dominant role of quasars in hydrogen reionization. | the pan-starrs1 z > 5.6 quasar survey. iii. the z ≈ 6 quasar luminosity function |
we present bolometric luminosities, black hole masses, and eddington ratios for 42 luminous quasars at z ≳ 6 using high signal-to-noise ratio vlt/x-shooter spectra, acquired as part of the enlarged eso large programme xqr-30. in particular, we derived the bolometric luminosities from the rest-frame 3000 å luminosities using a bolometric correction from the literature, as well as the black hole masses by modeling the spectral regions around the c iv 1549 å and the mg ii 2798 å emission lines, with scaling relations calibrated in the local universe. we find that the black hole masses derived from both emission lines are in the same range and the scatter of the measurements agrees with expectations from the scaling relations. the mg ii-derived masses are between ∼(0.8−12) ×109 m⊙ and the derived eddington ratios are within ∼0.13−1.73, with a mean (median) of 0.84(0.72). by comparing the total sample of quasars at z > 5.8, from this work and from the literature, to a bolometric luminosity distribution-matched sample at z ∼ 1.5, we find that quasars at high redshift host slightly less massive black holes, which accrete slightly more rapidly than those at lower z, with a difference in the mean eddington ratios of the two samples of ∼0.27. these findings are in agreement with the results of recent works in the literature. | xqr-30: black hole masses and accretion rates of 42 z ≳ 6 quasars |
previously, we demonstrated that mgii and civ reverberation-mapped quasars (rm qsos) are standardizable and that the cosmological parameters inferred using the broad-line region radius-luminosity (r-l) relation are consistent with those determined from better-established cosmological probes. with more data expected from ongoing and future spectroscopic and photometric surveys, it is imperative to examine how new qso data sets of varied quality, with their own specific luminosity and time-delay distributions, can be best used to determine more restrictive cosmological parameter constraints. in this study, we test the effect of adding 25 ozdes mgii rm qsos as well as 25 lower-quality sdss rm civ qsos, which increases the previous sample of rm qsos by $\sim 36\%$. although cosmological parameter constraints become tighter for some cosmological models after adding these new qsos, the new combined data sets have increased differences between r-l parameter values obtained in different cosmological models and thus a lower standardizability for the larger mgii + civ compilation. different time-delay methodologies, particularly the iccf and cream methods used for inferring time delays of sdss rm qsos, slightly affect cosmological and r-l relation parameter values, however, the effect is negligible for (smaller) compilations of robust time-delay detections. our analysis indicates that increasing the sample size is not sufficient for tightening cosmological constraints and a quality cut is necessary to obtain a standardizable rm qso sample. | effects of heterogeneous data sets and time-lag measurement techniques on cosmological parameter constraints from mgii and civ reverberation-mapped quasar data |
cosmological models and their parameters are widely debated because of theoretical and observational mismatches of the standard cosmological model, especially the current discrepancy between the value of the hubble constant, $h_{0}$, obtained by type ia supernovae (sne ia), and the cosmic microwave background radiation (cmb). thus, considering high-redshift probes like quasars (qsos), having intermediate redshifts between sne ia and cmb, is a necessary step. in this work, we use sne ia and the most updated qso sample, reaching redshifts up to $z\sim7.5$, applying the risaliti-lusso qso relation based on a non-linear relation between ultraviolet and x-ray luminosities. we consider this relation both in its original form and corrected for selection biases and evolution in redshift through a reliable statistical method also accounting for the circularity problem. we also explore two approaches: with and without calibration on sne ia. we then investigate flat and non-flat standard cosmological models and a flat $w$cdm model, with a constant dark energy equation of state parameter $w$. remarkably, when correcting for the evolution as a function of cosmology, we obtain closed constraints on $\omega_m$ using only non-calibrated qsos. we find that considering non-calibrated qsos combined with sne ia and accounting for the same correction, our results are compatible with a flat $\lambda$cdm model with $\omega_m = 0.3$ and $h_0 = 70 \, \mathrm{km\,s^{-1}\,mpc^{-1}}$. intriguingly, the $h_0$ values obtained place halfway between the one from sne ia and cmb, paving the way for new insights into the $h_0$ tension. | a bias-free cosmological analysis with quasars alleviating $h_0$ tension |
red quasars are candidate young objects in an early transition stage of massive galaxy evolution. our team recently discovered a population of extremely red quasars (erqs) in the baryon oscillation spectroscopic survey (boss) that has a suite of peculiar emission-line properties including large rest equivalent widths (rews), unusual `wingless' line profiles, large n v/lyα, n v/c iv, si iv/c iv and other flux ratios, and very broad and blueshifted [o iii] λ5007. here we present a new catalogue of c iv and n v emission-line data for 216 188 boss quasars to characterize the erq line properties further. we show that they depend sharply on uv-to-mid-ir colour, secondarily on rew(c iv), and not at all on luminosity or the baldwin effect. we identify a `core' sample of 97 erqs with nearly uniform peculiar properties selected via i-w3 ≥ 4.6 (ab) and rew(c iv) ≥ 100 å at redshifts 2.0-3.4. a broader search finds 235 more red quasars with similar unusual characteristics. the core erqs have median luminosity <log l(ergs s-1)> ∼ 47.1, sky density 0.010 deg-2, surprisingly flat/blue uv spectra given their red uv-to-mid-ir colours, and common outflow signatures including bals or bal-like features and large c iv emission-line blueshifts. their seds and line properties are inconsistent with normal quasars behind a dust reddening screen. we argue that the core erqs are a unique obscured quasar population with extreme physical conditions related to powerful outflows across the line-forming regions. patchy obscuration by small dusty clouds could produce the observed uv extinctions without substantial uv reddening. | extremely red quasars in boss |
we study the broad emission line blazars detected in the γ-ray band by the large area telescope onboard the fermi satellite and with the optical spectrum studied by shaw et al. the observed broad line strength provides a measure of the ionizing luminosity of the accretion disc, while the γ-luminosity is a proxy for the bolometric non-thermal beamed jet emission. the resulting sample, composed by 217 blazars, is the best suited to study the connection between accretion and jet properties. we compare the broad emission line properties of these blazars with those of radio-quiet and radio-loud quasars present in the sloan digital sky survey, to asses differences and similarities of the disc luminosity and the virial black hole mass. for most sources, we could derive the black hole mass by reproducing the ir-optical-uv data with a standard accretion disc spectrum, and we compared the black hole masses derived with the two methods. the distributions of the masses estimated in the two ways agree satisfactorily. we then apply a simple, one-zone, leptonic model to all the 217 objects of our sample. the knowledge of the black hole mass and disc luminosity helps to constrain the jet parameters. on average, they are similar to what found by previous studies of smaller samples of sources. | fermi/lat broad emission line blazars |
we report new iram/pdbi, jcmt/scuba-2, and vla observations of the ultraluminous quasar sdss j010013.02+280225.8 (hereafter, j0100+2802) at z = 6.3, which hosts the most massive supermassive black hole (smbh), 1.24× {10}10 {m}⊙ , that is known at z > 6. we detect the [c ii] 158 μm fine structure line and molecular co(6-5) line and continuum emission at 353, 260, and 3 ghz from this quasar. the co(2-1) line and the underlying continuum at 32 ghz are also marginally detected. the [c ii] and co detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. the redshift determined with the [c ii] and co lines shows a velocity offset of ∼ 1000 {km} {{{s}}}-1 from that measured with the quasar mg ii line. the co (2-1) line luminosity provides a direct constraint on the molecular gas mass, which is about (1.0+/- 0.3)× {10}10 {m}⊙ . we estimate the fir luminosity to be (3.5+/- 0.7)× {10}12 {l}⊙ , and the uv-to-fir spectral energy distribution of j0100+2802 is consistent with the templates of the local optically luminous quasars. the derived [c ii]-to-fir luminosity ratio of j0100+2802 is 0.0010 ± 0.0002, which is slightly higher than the values of the most fir luminous quasars at z ∼ 6. we investigate the constraint on the host galaxy dynamical mass of j0100+2802 based on the [c ii] line spectrum. it is likely that this ultraluminous quasar lies above the local smbh-galaxy mass relationship, unless we are viewing the system at a small inclination angle. | probing the interstellar medium and star formation of the most luminous quasar at z = 6.3 |
we report new alma observations of the co(3-2) line emission from the 2.1+/- 0.3× {10}10 {m}⊙molecular gas reservoir in the central galaxy of the phoenix cluster. the cold molecular gas is fueling a vigorous starburst at a rate of 500{--}800 {m}⊙{{yr}}-1 and powerful black hole activity in the forms of both intense quasar radiation and radio jets. the radio jets have inflated huge bubbles filled with relativistic plasma into the hot, x-ray atmospheres surrounding the host galaxy. the alma observations show that extended filaments of molecular gas, each 10{--}20 {kpc} long with a mass of several billion solar masses, are located along the peripheries of the radio bubbles. the smooth velocity gradients and narrow line widths along each filament reveal massive, ordered molecular gas flows around each bubble, which are inconsistent with gravitational free-fall. the molecular clouds have been lifted directly by the radio bubbles, or formed via thermal instabilities induced in low-entropy gas lifted in the updraft of the bubbles. these new data provide compelling evidence for close coupling between the radio bubbles and the cold gas, which is essential to explain the self-regulation of feedback. the very feedback mechanism that heats hot atmospheres and suppresses star formation may also paradoxically stimulate production of the cold gas required to sustain feedback in massive galaxies. | alma observations of massive molecular gas filaments encasing radio bubbles in the phoenix cluster |
we demonstrate the presence of an extended and massive circumgalactic medium (cgm) around messier 31 using archival hst cosmic origins spectrograph ultraviolet spectroscopy of 18 qsos projected within two virial radii of m31 ({{r}vir}=300 kpc). we detect absorption from si iii at -300≲ {{v}lsr}≲ -150 km s-1 toward all three sightlines at r≲ 0.2{{r}vir}, 3 of 4 sightlines at 0.8≲ r/{{r}vir}≲ 1.1, and possibly 1 of 11 at 1.1< r/{{r}vir}≲ 1.8. we present several arguments that the gas at these velocities observed in these directions originates from the m31 cgm rather than the local group or milky way cgm or magellanic stream. we show that the dwarf galaxies located in the cgm of m31 have very similar velocities over similar projected distances from m31. we find a non-trivial relationship only at these velocities between the column densities (n) of all the ions and r, whereby n decreases with increasing r. at r< 0.8{{r}vir}, the covering fraction is close to unity for si iii and c iv ({{f}c}∼ 60%-97% at the 90% confidence level), but drops to {{f}c}≲ 10%-20% at r≳ {{r}vir}. we show that the m31 cgm gas is bound, multiphase, predominantly ionized, and is more highly ionized gas at larger r. we estimate using si ii, si iii, and si iv, a cgm metal mass of ≳ 2× {{10}6} m⊙and gas mass of ≳ 3× {{10}9}({{z}⊙ }/z) m⊙within 0.2{{r}vir}, and possibly a factor of ∼10 larger within {{r}vir}, implying substantial metal and gas masses in the cgm of m31. 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 no. nas5-26555. | evidence for a massive, extended circumgalactic medium around the andromeda galaxy |
the gravitationally lensed galaxy a1689-zd1 is one of the most distant spectroscopically confirmed sources (z = 7.5). it is the earliest known galaxy where the interstellar medium (ism) has been detected; dust emission was detected with the atacama large millimetre array (alma). a1689-zd1 is also unusual among high-redshift dust emitters as it is a sub-l★ galaxy and is therefore a good prospect for the detection of gaseous ism in a more typical galaxy at this redshift. we observed a1689-zd1 with alma in bands 6 and 7 and with the green bank telescope (gbt) in band q. to study the structure of a1689-zd1, we map the mm-thermal dust emission and find two spatial components with sizes about 0.4 - 1.7 kpc (lensing-corrected). the rough spatial morphology is similar to what is observed in the near-infrared with hst and points to a perturbed dynamical state, perhaps indicative of a major merger or a disc in early formation. the alma photometry is used to constrain the far-infrared spectral energy distribution, yielding a dust temperature (tdust ∼ 35-45 k for β = 1.5 - 2). we do not detect the co(3-2) line in the gbt data with a 95 per cent upper limit of 0.3 mjy observed. we find a slight excess emission in alma band 6 at 220.9 ghz. if this excess is real, it is likely due to emission from the [c ii] 158.8 μm line at z_[c ii] = 7.603. the stringent upper limits on the [c ii] lfir luminosity ratio suggest a [c ii] deficit similar to several bright quasars and massive starbursts. | a merger in the dusty, z = 7.5 galaxy a1689-zd1? |
in the last few years, it became possible to observationally resolve galaxies with two distinct nuclei in their centre. for separations smaller than 10 kpc, dual and offset active galactic nuclei (agn) are distinguished: in dual agn, both nuclei are active, whereas in offset agn only one nucleus is active. to study the origin of such agn pairs, we employ a cosmological, hydrodynamic simulation with a large volume of (182 mpc)3 from the set of magneticum pathfinder simulations. the simulation self-consistently produces 35 resolved black hole (bh) pairs at redshift z = 2, with a comoving distance smaller than 10 kpc. 14 of them are offset agn and nine are dual agn, resulting in a fraction of (1.2 ± 0.3) per cent agn pairs with respect to the total number of agn. in this paper, we discuss fundamental differences between the bh and galaxy properties of dual agn, offset agn and inactive bh pairs and investigate their different triggering mechanisms. we find that in dual agn the bhs have similar masses and the corresponding bh from the less massive progenitor galaxy always accretes with a higher eddington ratio. in contrast, in offset agn the active bh is typically more massive than its non-active counterpart. furthermore, dual agn in general accrete more gas from the intergalactic medium than offset agn and non-active bh pairs. this highlights that merger events, particularly minor mergers, do not necessarily lead to strong gas inflows and thus, do not always drive strong nuclear activity. | origin and properties of dual and offset active galactic nuclei in a cosmological simulation at z=2 |
we recently used hydrochemical simulations to demonstrate that molecular outflows observed in luminous quasars can be explained by molecule formation within the active galactic nucleus (agn) wind. however, these simulations cover a limited parameter space due to their computational cost. we have therefore developed an analytic model to follow cooling in the shocked interstellar medium (ism) layer of an agn wind. we explore different ambient densities (1-104 {cm}^{-3}), density profile slopes (0-1.5), agn luminosities (1044-10^{47} {erg} {s}^{-1}), and metallicities (0.1-3 z⊙). the swept-up gas mostly cools within ∼1 myr. based on our previous simulations, we predict that this gas would produce observable molecular outflows. the instantaneous momentum boost initially increases as the outflow decelerates. however, it reaches a maximum of ≈20, due to work done against the gravitational potential. the predicted time-averaged observational estimate of the molecular outflow momentum boost reaches a maximum of ≈1-2, partly due to our assumed molecular fraction, 0.2, but also because the instantaneous and observational, time-averaged definitions are not equivalent. thus recent observational estimates of order unity momentum boosts do not necessarily rule out energy-driven outflows. finally, we find that dust grains are likely to re-form by accretion of metals after the shocked ism layer has cooled, assuming that a small fraction of dust grains swept up after this layer has cooled are able to mix into the cool phase, and assuming that grain growth remains efficient in the presence of the strong agn radiation field. this would enable rapid molecule formation, as assumed in our models. | radiative cooling of swept-up gas in agn-driven galactic winds and its implications for molecular outflows |
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