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in area and depth, the pan-starrs1 (ps1) 3π survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. ps1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike sdss, not simultaneously across the... | finding, characterizing, and classifying variable sources in multi-epoch sky surveys: qsos and rr lyrae in ps1 3π data |
cosmograil is a long-term photometric monitoring of gravitationally lensed quasars aimed at implementing refsdal's time-delay method to measure cosmological parameters, in particular h0. given the long and well sampled light curves of strongly lensed quasars, time-delay measurements require numerical techniques whose q... | cosmograil: the cosmological monitoring of gravitational lenses. xv. assessing the achievability and precision of time-delay measurements |
the lyman-α forest is a powerful probe for cosmology, but it is also strongly impacted by galaxy evolution and baryonic processes such as active galactic nucleus (agn) feedback, which can redistribute mass and energy on large scales. we constrain the signatures of agn feedback on the 1d power spectrum of the lyman-α fo... | the impact of agn feedback on the 1d power spectra from the ly α forest using the horizon-agn suite of simulations |
we describe a multiwavelength program of monitoring of a sample of bright γ-ray blazars, which the boston university (bu) group has being carrying out since june 2007. the program includes monthly monitoring with the very long baseline array at 43 ghz, optical photometric and polarimetric observations, construction and... | the vlba-bu-blazar multi-wavelength monitoring program |
we use the sky-average spectrum measured by edges high-band (90-190 mhz) to constrain parameters of early galaxies independent of the absorption feature at 78 mhz reported by bowman et al. these parameters represent traditional models of cosmic dawn and the epoch of reionization produced with the 21cmfast simulation co... | results from edges high-band. ii. constraints on parameters of early galaxies |
we investigate the blazar contribution to the cumulative neutrino intensity assuming a generic relationship between neutrino and gamma-ray luminosities, ${l}_{\nu }\propto {({l}_{\mathrm{ph}})}^{{\gamma }_{\mathrm{lw}}}$ l ν ∝ ( l ph ) γ lw . using the gamma-ray luminosity functions for blazars, including flat-spectrum... | complementarity of stacking and multiplet constraints on the blazar contribution to the cumulative high-energy neutrino intensity |
gravitational lensing has emerged as a powerful probe of the matter distribution on subgalactic scales, which itself may contain important clues about the fundamental origins and properties of dark matter. broadly speaking, two different approaches have been taken in the literature to map the small-scale structure of t... | beyond subhalos: probing the collective effect of the universe's small-scale structure with gravitational lensing |
to extend the search for quasars in the epoch of reionization beyond the tip of the luminosity function, we explore point-source candidates at redshift z ∼ 8 in superborg, a compilation of ∼0.4 deg2 archival medium-deep (mf160w ∼ 26.5 abmag, 5σ) parallel infrared (ir) images taken with the hubble space telescope (hst).... | superborg: exploration of point sources at z ∼ 8 in hst parallel fields |
we report the discovery and analysis of the most metal-poor damped lyman α (dla) system currently known, based on observations made with the keck hires spectrograph. the metal paucity of this system has only permitted the determination of three element abundances: [c/h] = -3.43 ± 0.06, [o/h] = -3.05 ± 0.05 and [si/h] =... | discovery of the most metal-poor damped lyman-α system |
galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of h0 from the time-delay technique. we present the results of a systematic spectroscopic identification of the galaxies in the f... | h0licow - ii. spectroscopic survey and galaxy-group identification of the strong gravitational lens system he 0435-1223 |
the lyα forest transmission probability distribution function (pdf) is an established probe of the intergalactic medium (igm) astrophysics, especially the temperature-density relationship of the igm. we measure the transmission pdf from 3393 baryon oscillations spectroscopic survey (boss) quasars from sloan digital sky... | igm constraints from the sdss-iii/boss dr9 lyα forest transmission probability distribution function |
active galactic nuclei (agn) vary in their brightness across all wavelengths. moreover, longer wavelength ultraviolet-optical continuum light curves appear to be delayed with respect to shorter wavelength light curves. a simple way to model these delays is by assuming thermal reprocessing of a variable point source (a ... | accretion disc time lag distributions: applying cream to simulated agn light curves |
we investigate the dependence of gas kinematics and column densities in the {{mg}} {{ii}}-absorbing circumgalactic medium on galaxy color, azimuthal angle, and inclination to trace baryon cycle processes. our sample of 30 foreground isolated galaxies at 0.3\lt {z}{{gal}}\lt 1.0, imaged with the hubble space telescope, ... | magiicat v. orientation of outflows and accretion determine the kinematics and column densities of the circumgalactic medium |
the chandra x-ray observatory has discovered dozens of resolved, kiloparsec-scale jets associated with powerful quasars in which the x-ray fluxes are observed to be much higher than the expected level based on the radio-optical synchrotron spectrum. the most popular explanation for the anomalously high and hard x-ray f... | ruling out ic/cmb x-rays in pks 0637-752 and the implications for tev emission from large-scale quasar jets |
recently, risaliti and lusso [nat. astron. 3, 272 (2019), 10.1038/s41550-018-0657-z] reported new measurements of the expansion rate of the universe by constructing the hubble diagram of 1598 quasars in the redshift range 0.5 <z <5.5 . it is claimed a 4 σ tension with the standard concordance λ cdm concerning bot... | is the hubble diagram of quasars in tension with concordance cosmology? |
we present alma band 7 observations at 850 μm of 20 luminous (log l_bol > 46.9 [erg s-1]) unobscured quasars at z ∼ 2. we detect continuum emission for 19/20 quasars. after subtracting an agn contribution, we measure the total far-ir luminosity for 18 quasars, assuming a modified blackbody model, and attribute the e... | no signs of star formation being regulated in the most luminous quasars at z ∼ 2 with alma |
the flat spectrum radio quasar 3c 279 is known to exhibit pronounced variability in the high-energy (100 mev < e < 100 gev) γ-ray band, which is continuously monitored with fermi-lat. during two periods of high activity in april 2014 and june 2015 target-of-opportunity observations were undertaken with the high e... | constraints on the emission region of 3c 279 during strong flares in 2014 and 2015 through vhe γ-ray observations with h.e.s.s. |
we present results from spectroscopic observations with x-shooter at the very large telescope of seven h2-bearing damped lyman-α systems (dlas) at high redshifts (zabs ∼ 2.5-3). these dlas were originally selected from the presence of strong h2 lines directly seen at the dla redshift in low-resolution low signal-to-noi... | x-shooter observations of strong h2-bearing dlas at high redshift |
in this manuscript, we report a new changing-look qso (clqso) sdss j2241 at z = 0.059. based on the multi-epoch sloan digital sky survey spectra from 2011 to 2017, the flux ratio of broad hα to broad hβ has changed from 7 in 2011 to 2.7 in 2017, leading sdss j2241 with a spectral index αλ ~ -5.21 ± 0.02 (λ < 4000) i... | the bluest changing-look qso sdss j224113-012108 |
the upcoming radio interferometer square kilometre array (ska) is expected to directly detect the redshifted 21-cm signal from the neutral hydrogen present during the cosmic dawn. temperature fluctuations from x-ray heating of the neutral intergalactic medium can dominate the fluctuations in the 21-cm signal from this ... | evaluating the qso contribution to the 21-cm signal from the cosmic dawn |
we report the discovery of six spatially extended (10-100 kpc) line-emitting nebulae in the z ≈ 0.57 galaxy group hosting pks 0405-123, one of the most luminous quasars at z < 1. the discovery is enabled by the multi unit spectroscopic explorer and provides tantalizing evidence connecting large-scale gas streams wit... | galaxy and quasar fueling caught in the act from the intragroup to the interstellar medium |
we investigate possible factors that drive fast quasar outflows using a sample of 39,249 quasars at median redshift $\langle z \rangle \approx$ 2.17. unique to this study, the quasar redshifts are re-measured based on the mg ii emission line, allowing for exploration of unprecedented outflow velocities (>6000 km/s) ... | boss quasar outflows traced by c iv |
we present constraints on the amplitude of local primordial non-gaussianities (png), $f_{\rm nl}$, using the quasar sample in the sloan digital sky survey iv extended baryon oscillation spectroscopic survey data release 16. we analyze the power spectrum monopole, testing for the presence of scale dependent galaxy bias ... | optimal constraints on primordial non-gaussianity with the eboss dr16 quasars in fourier space |
recently, the lyman-$\alpha$ (ly$\alpha$) forest flux auto-correlation function has been shown to be sensitive to the mean free path of hydrogen-ionizing photons, $\lambda_{\text{mfp}}$, for simulations at $z \geq 5.4$. measuring $\lambda_{\text{mfp}}$ at these redshifts will give vital information on the ending of rei... | measurements of the $z > 5$ lyman-$\\alpha$ forest flux auto-correlation functions from the extended xqr-30 data set |
a characteristic feature of quasars is the observed non-linear relationship between their monochromatic luminosities at rest-frame 2500 å and 2 kev. this relationship is evident across all redshifts and luminosities and, due to its non-linearity, can be implemented to estimate quasar distances and construct a hubble di... | quasars as standard candles v. evaluation of a $\\leq$ 0.06 dex intrinsic dispersion in the lx-luv relation |
the flux ratios of gravitationally lensed quasars provide a powerful probe of the nature of dark matter. importantly, these ratios are sensitive to small-scale structure, irrespective of the presence of baryons. this sensitivity may allow us to study the halo mass function even below the scales where galaxies form obse... | jwst lensed quasar dark matter survey i: description and first results |
we study the dipole signal in the spectral index (x) of the differential number counts using quasars in the catwise2020 catalog of infrared sources. the index is extracted by using the log-likelihood method. we obtain the value $x=1.579 \pm 0.001$ for a quasar sample of 1355352 sources. we extract the dipole signal in ... | probing cosmological principle using the spectral index of quasar flux distribution |
we present a free-form lens model for the multiply lensed quasar in the galaxy cluster sdss j$1004+4112$. our lens model makes minimal assumptions about the distribution of mass in the lens plane. we pay particular attention to the model uncertainties on the predicted time delay, originating from the particular configu... | parameter free hubble constant from the quadruply lensed quasar sdss j1004 + 4112 |
the well-studied blazar 3c 279 underwent a giant γ-ray outburst in 2014 march-april. the measured γ-ray flux (1.21 ± 0.10 × 10-5 ph c{{m}-2} {{s}-1} in a 0.1-300 gev energy range) is the highest detected from 3c 279 by the fermi large area telescope. hour-scale γ-ray flux variability is observed, with a flux doubling t... | multi-wavelength observations of 3c 279 during the extremely bright gamma-ray flare in 2014 march-april |
the correlation between the x-ray and uv luminosities observed in quasars, spanning a wide redshift range and holding true for several decades in both spectral bands, suggests the presence of a universal mechanism governing the transfer of energy from the accretion disc to the hot corona. in this study, we leverage x-r... | the relation between x-ray and uv emission in quasars |
we study the time lags between the continuum emission of quasars at different wavelengths, based on more than four years of multi-band (g, r, i, z) light curves in the pan-starrs medium deep fields. as photons from different bands emerge from different radial ranges in the accretion disk, the lags constrain the sizes o... | detection of time lags between quasar continuum emission bands based on pan-starrs light curves |
a complete census of baryons in the late universe is a long-standing challenge due to the intermediate temperate and rarefied character of the majority of cosmic gas. to gain insight into this problem, we extract measurements of the kinematic sunyaev-zel'dovich (ksz) effect from the cross-correlation of angular redshif... | measuring the evolution of intergalactic gas from z = 0 to 5 using the kinematic sunyaev-zel'dovich effect |
context. qso b0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. the gravitational lensing splits the emitted radiation into two components that are spatially indistinguishable by gamma-ray instruments, but separated by a 10-12 day delay. in july 2014, qso b0218+357 experienced a violent flare ... | detection of very high energy gamma-ray emission from the gravitationally lensed blazar qso b0218+357 with the magic telescopes |
accreting supermassive black holes (smbhs) frequently power jets that interact with the interstellar/circumgalactic medium (ism/cgm), regulating star-formation in the galaxy. highly supersonic jets launched by active galactic nuclei (agn) power a cocoon that confines them and shocks the ambient medium. we build upon th... | dissipation of agn jets in a clumpy interstellar medium |
in theoretical models of galaxy evolution, black hole feedback is a necessary ingredient in order to explain the observed exponential decline in number density of massive galaxies. most contemporary black hole feedback models in cosmological simulations rely on a constant radiative efficiency (usually $\eta \sim 0.1$) ... | three regimes of black hole feedback |
cosmological simulations of the low-density intergalactic medium exhibit a strikingly tight power-law relation between temperature and density that holds over two decades in density. it is found that this relation should roughly apply δz ∼ 1-2 after a reionization event, and this limiting behaviour has motivated the po... | on the intergalactic temperature-density relation |
we examine the 2008-2016 γ-ray and optical light curves of three bright bl lac objects, 0716+714, mrk 421, bl lac, which exhibit large structured variability. we searched for periodicities by using a fully bayesian approach. for two out of three sources investigated, no significant periodic variability was found. in th... | gamma-ray and optical oscillations of 0716+714, mrk 421, and bl lacertae |
we examine the properties of the host galaxies of $z=7$ quasars using the large volume, cosmological hydrodynamical simulation bluetides. we find that the 10 most massive black holes and the 191 quasars in the simulation (with $m_{\textrm{uv,agn}}\lt m_{\textrm{uv,host}}$) are hosted by massive galaxies with stellar ma... | the host galaxies of z = 7 quasars: predictions from the bluetides simulation |
context. icecube has reported a very-high-energy neutrino (icecube-170922a) in a region containing the blazar txs 0506+056. correlated gamma-ray activity has led to the first high-probability association of a high-energy neutrino with an extragalactic source. this blazar has been found to be in a radio outburst during ... | apparent superluminal core expansion and limb brightening in the candidate neutrino blazar txs 0506+056 |
proximity zones of high-redshift quasars are unique probes of supermassive black hole formation, but simultaneously explaining proximity zone sizes and black hole masses has proved to be challenging. we study the robustness of some of the assumptions that are usually made to infer quasar lifetimes from proximity zone s... | the need for obscured supermassive black hole growth to explain quasar proximity zones in the epoch of reionization |
we present new 5 ghz very large array observations of a sample of eight active intermediate-mass black holes with masses 104.9 m⊙ < m < 106.1 m⊙ found in galaxies with stellar masses m* < 3 × 109 m⊙. we detected five of the eight sources at high significance. of the detections, four were consistent with a poin... | intermediate-mass black holes and the fundamental plane of black hole accretion |
we propose a solution to the problem of accretion disc sizes in active galactic nuclei being larger when measured by reverberation mapping than predicted by theory. considering the disc's exposed-surface thickness profile h(r), our solution invokes a steep rim or rippled structures irradiated by the central lamp-post. ... | rimmed and rippled accretion disc models to explain agn continuum lags |
we study dual agn host galaxy morphologies at $z=2$ using the astrid simulation, selecting black hole (bh) pairs with small separation ($\delta r<30\rm{kpc}$), high mass ($m_{\text{bh,12}}>10^7m_\odot$), and luminosity ($l_{\text{bol,12}}>10^{43}\rm{erg/s}$). we kinematically decompose (using mordor) $\sim1000... | z~2 dual agn host galaxies are disky: stellar kinematics in the astrid simulation |
using mock data for the hubble diagrams of type ia supernovae (snia) and quasars (qsos) generated based on the standard model of cosmology, and using the least-squares method based on the markov-chain-monte-carlo (mcmc) algorithm, we first put constraints on the cosmographic parameters in the context of the various mod... | can high-redshift hubble diagrams rule out the standard model of cosmology in the context of cosmography? |
synthetic data sets are used in cosmology to test analysis procedures, to verify that systematic errors are well understood and to demonstrate that measurements are unbiased. in this work we describe the methods used to generate synthetic datasets of lyman-$\alpha$ quasar spectra aimed for studies with the dark energy ... | synthetic spectra for lyman-$\\alpha$ forest analysis in the dark energy spectroscopic instrument |
the link between the circumgalactic medium (cgm) and the stellar growth of massive galaxies at high-z depends on the properties of the widespread cold molecular gas. as part of the supercold-cgm survey (survey of protocluster elane revealing co/[c i] in the lyα-detected cgm), we present the radio-loud qso q1228+3128 at... | massive molecular outflow and 100 kpc extended cold halo gas in the enormous lyα nebula of qso 1228+3128 |
we use zoom simulations to show how merger-driven disruption of the gas disc in a galaxy provides its central active galactic nucleus (agn) with fuel to drive outflows that entrain and expel a significant fraction of the circumgalactic medium (cgm). this in turn suppresses replenishment of the interstellar medium, caus... | galaxy mergers can initiate quenching by unlocking an agn-driven transformation of the baryon cycle |
quasar accretion-disc outflows might play an important role in galaxy evolution, but they are notoriously difficult to study due to line saturation and blending problems in the ly α forest. we circumvent these problems by constructing median composite spectra of diverse broad absorption lines (bals) and `mini-bals' in ... | on the structure and energetics of quasar broad absorption-line outflows |
we perform the first broadband study of mrk421 from radio to tev gamma rays with simultaneous measurements of the x-ray polarization from ixpe. the data were collected within an extensive multiwavelength campaign organized between may and june 2022 using magic, fermi-lat, nustar, xmm-newton, swift, and several optical ... | first characterization of the emission behavior of mrk421 from radio to vhe gamma rays with simultaneous x-ray polarization measurements |
the legacy survey of space and time (lsst) by the vera c. rubin observatory is expected to discover tens of millions of quasars. a significant fraction of these could be powered by coalescing massive black hole (mbh) binaries, since many quasars are believed to be triggered by mergers. we show that under plausible assu... | ultra-short-period massive black hole binary candidates in lsst as lisa 'verification binaries' |
we derive the statistical properties of neutral gas at redshifts 0.11 < z < 1.65 from ultraviolet (uv) measurements of quasar ly α absorption lines corresponding to 369 mg ii systems with w^{λ 2796}0 ≥ 0.3 å. in addition to the 41 damped lyman alpha (dla) systems presented in rao et al. (2006), the current dla sa... | the statistical properties of neutral gas at z < 1.65 from uv measurements of damped lyman alpha systems |
we present a new model-independent method to determine spatial curvature and to mitigate the circularity problem affecting the use of quasars as distance indicators. cosmic-chronometer measurements are used to construct the curvature-dependent luminosity distance ${d}_{l}^{\mathrm{cal}}({{\rm{\omega }}}_{k},z)$ using a... | model-independent distance calibration and curvature measurement using quasars and cosmic chronometers |
deep observations have detected extended lyα emission nebulae surrounding tens of quasars at redshift 2-6. however, the metallicity of such extended halos is still poorly understood. we perform a detailed analysis on a large sample of 80 quasars at z ∼ 3 based on muse-vlt data. we find clear evidence of extended emissi... | metal enrichment in the circumgalactic medium and lyα halos around quasars at z ∼ 3 |
we present a hubble space telescope space telescope imaging spectrograph spectrum of asassn-14li, the first rest-frame ultraviolet (uv) spectrum of a tidal disruption flare (tdf). the underlying continuum is well fit by a blackbody with {t}{uv}=3.5× {10}4 k, an order of magnitude smaller than the temperature inferred f... | an ultraviolet spectrum of the tidal disruption flare asassn-14li |
in the context of the flashlight survey, we obtained deep narrowband images of 15 z ∼ 2 quasars with the gemini multi-object spectrograph on gemini south in an effort to measure lyα emission from circum- and intergalactic gas on scales of hundreds of kpc from the central quasar. we do not detect bright giant lyα nebula... | the stacked lyα emission profile from the circum-galactic medium of z ∼ 2 quasars |
we combine cosmological hydrodynamic simulations with analytic models to evaluate the role of galaxy-scale gravitational torques on the evolution of massive black holes at the centers of star-forming galaxies. we confirm and extend our earlier results to show that torque-limited growth yields black holes and host galax... | torque-limited growth of massive black holes in galaxies across cosmic time |
we use the observed unresolved cosmic x-ray background (cxrb) in the 0.5-2 kev band and existing upper limits on the 21-cm power spectrum to constrain the high-redshift population of x-ray sources, focusing on their effect on the thermal history of the universe and the cosmic 21-cm signal. because the properties of the... | constraining the redshifted 21-cm signal with the unresolved soft x-ray background |
in these proceedings we describe the weave-qso survey, which will observe around 400,000 high redshift quasars starting in 2018. this survey is part of a broader weave survey to be conducted at the 4.2m william herschel telescope. we will focus on chiefly on the science goals, but will also briefly summarise the target... | weave-qso: a massive intergalactic medium survey for the william herschel telescope |
we present detailed image analysis of rest-frame optical images of 235 low-redshift (z ≲ 0.35) type 1 active galactic nuclei (agns) observed with the hubble space telescope. the high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the hos... | stellar photometric structures of the host galaxies of nearby type 1 active galactic nuclei |
we study the link between supermassive black hole growth and the stellar mass assembly of their host galaxies in the state-of-the-art romulus suite of simulations. the cosmological simulations romulus25 and romulusc employ innovative recipes for the seeding, accretion, and dynamics of black holes in the field and clust... | tracing black hole and galaxy co-evolution in the romulus simulations |
aims: the aim of this paper is to investigate the claim that stars in the lensing galaxy of a gravitationally lensed quasar system can always account for the observed microlensing of the individual quasar images.methods: a small sample of gravitationally lensed quasar systems was chosen where the quasar images appear t... | the signature of primordial black holes in the dark matter halos of galaxies |
we present spatially resolved echelle spectroscopy of an intervening mg ii-fe ii-mg i absorption-line system detected at zabs = 0.73379 towards the giant gravitational arc psz1 g311.65-18.48. the absorbing gas is associated with an inclined disc-like star-forming galaxy, whose major axis is aligned with the two arc-seg... | slicing the cool circumgalactic medium along the major axis of a star-forming galaxy at z = 0.7 |
strongly lensed explosive transients such as supernovae, gamma-ray bursts, fast radio bursts, and gravitational waves are very promising tools to determine the hubble constant (h0) in the near future in addition to strongly lensed quasars. in this work, we show that the transient nature of the point source provides an ... | improved time-delay lens modelling and h0 inference with transient sources |
hot, dust-obscured galaxies, or “hot dogs,” are a rare, dusty, hyperluminous galaxy population discovered by the wise mission. predominantly at redshifts 2-3, they include the most luminous known galaxies in the universe. their high luminosities likely come from accretion onto highly obscured supermassive black holes (... | eddington-limited accretion in z ∼ 2 wise-selected hot, dust-obscured galaxies |
in the coming decade, a new generation of telescopes, including jwst and wfirst, will probe the period of the formation of first galaxies and quasars, and open up the last frontier for structure formation. recent simulations and observations have suggested that these galaxies are strongly clustered (with large-scale bi... | cosmic variance of z > 7 galaxies: prediction from bluetides |
measurements of the lyα forest based on large numbers of quasar spectra from sky surveys such as sdss/eboss accurately probe the distribution of matter on small scales and thus provide important constraints on several ingredients of the cosmological model. a main summary statistic derived from those measurements is the... | simulating intergalactic gas for desi-like small scale lymanα forest observations |
understanding the fe ii emission from active galactic nuclei (agns) has been a grand challenge for many decades. the rewards from understanding the agn spectra would be immense, involving both quasar classification schemes such as "eigenvector 1" and tracing the chemical evolution of the cosmos. recently, three large f... | improved fe ii emission-line models for agns using new atomic data sets |
the leading contenders for the seeds of z > 6 quasars are direct-collapse black holes (dcbhs) forming in atomically cooled haloes at z ~ 20. however, the lyman-werner (lw) uv background required to form dcbhs of 105 m⊙ are extreme, about 104 j21, and may have been rare in the early universe. here we investigate the ... | radiation hydrodynamical simulations of the birth of intermediate-mass black holes in the first galaxies |
we present the results from 685 mhz observations with the upgraded giant metrewave radio telescope (ugmrt) of 22 quasars belonging to the palomar-green (pg) quasar sample. only four sources reveal extended radio structures on ∼10-30 kpc scales, while the rest are largely a combination of a radio core unresolved at the ... | probing the origin of low-frequency radio emission in pg quasars with the ugmrt - i |
active galactic nuclei (agns) have long been observed to "twinkle" (i.e., their brightness varies with time) on timescales from days to years in the uv/optical bands. such agn uv/optical variability is essential for probing the physics of supermassive black holes (smbhs), the accretion disk, and the broad-line region. ... | corona-heated accretion-disk reprocessing: a physical model to decipher the melody of agn uv/optical twinkling |
the standard model of cosmology, lambda cold dark matter (λcdm), is the simplest model that matches the current observations, but it relies on two hypothetical components, to wit, dark matter and dark energy. future galaxy surveys and cosmic microwave background (cmb) experiments will independently shed light on these ... | cosmological constraints from a joint analysis of cosmic microwave background and spectroscopic tracers of the large-scale structure |
we propose that one of the sources in the recently detected system cr7 by sobral et al. through spectrophotometric measurements at z = 6.6 harbours a direct collapse black hole (dcbh). we argue that the lw radiation field required for direct collapse in source a is provided by sources b and c. by tracing the lw product... | detecting direct collapse black holes: making the case for cr7 |
we present multi-wavelength observations and modeling of the exceptionally bright long γ-ray burst grb 160625b. the optical and x-ray data are well fit by synchrotron emission from a collimated blastwave with an opening angle of {θ }j≈ 3\buildrel{\circ}\over{.} 6 and kinetic energy of {e}k≈ 2× {10}51 erg, propagating i... | a reverse shock and unusual radio properties in grb 160625b |
context. the kids strongly lensed quasar detection project (kids-squad) is aimed at finding as many previously undiscovered gravitational lensed quasars as possible in the kilo degree survey. this is the second paper of this series where we present a new, automatic object-classification method based on the machine lear... | kids-squad. ii. machine learning selection of bright extragalactic objects to search for new gravitationally lensed quasars |
we use star, galaxy and quasar spectra taken by the sloan digital sky survey to map out the distribution of diffuse interstellar bands (dibs) induced by the milky way. after carefully removing the intrinsic spectral energy distribution of each source, we show that by stacking thousands of spectra, it is possible to mea... | exploring the diffuse interstellar bands with the sloan digital sky survey |
we present multi-frequency (1-8 ghz) very large array data, combined with visible multiobject spectrograph integral field unit data and hubble space telescope imaging, of a z = 0.085 radio-quiet type 2 quasar (with l 1.4 ghz ≈ 5 × 1023 w hz-1 and l agn ≈ 2 × 1045 erg s-1). due to the morphology of its emission-line reg... | storm in a "teacup": a radio-quiet quasar with ≈10 kpc radio-emitting bubbles and extreme gas kinematics |
flat-spectrum radio-loud narrow-line seyfert 1 galaxies (nls1s) are a recently discovered class of γ-ray emitting active galactic nuclei (agn), that exhibit some blazar-like properties which are explained with the presence of a relativistic jet viewed at small angles. when blazars are observed at larger angles they app... | parent population of flat-spectrum radio-loud narrow-line seyfert 1 galaxies |
we perform long-term (≈15 years, observed-frame) x-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (agns) in the 6 ms chandra deep field-south survey; the majority are in the redshift range of 0.6-3.1, providing access to penetrating rest-frame x-rays up to ≈10-30 kev. of the 68 sources,... | long-term x-ray variability of typical active galactic nuclei in the distant universe |
we investigate the presence of extended ionized outflows in 18 luminous type 2 agns (11 quasars and 7 high-luminosity seyfert 2s) at 0.3 < z < 0.6 based on vlt-fors2 spectroscopy. we infer typical lower limits on the radial sizes of the outflows ro ≳ several × 100 pc and upper limits ro ≲ 1-2 kpc. our results are... | ionized outflows in luminous type 2 agns at z < 0.6: no evidence for significant impact on the host galaxies |
the origin, geometry, and kinematics of the broad-line region (blr) gas in quasars and active galactic nuclei (agn) are uncertain. we demonstrate that clumpy biconical disc winds illuminated by an agn continuum can produce blr-like spectra. we first use a simple toy model to illustrate that disc winds make quite good b... | stratified disc wind models for the agn broad-line region: ultraviolet, optical, and x-ray properties |
quasars have long been known as intrinsically variable sources, but the physical mechanism underlying the temporal optical/uv variability is still not well understood. we propose a novel nonparametric method for modeling and forecasting the optical variability of quasars utilizing an ae neural network to gain insight i... | deep modeling of quasar variability |
we use the sloan digital sky survey (sdss) quasar data release 12 (dr12q), containing nearly 300,000 active galactic nuclei (agns), to calculate the monochromatic luminosities at 5100, 3000, and 1350 å, derived from the broadband extinction-corrected sdss magnitudes. after matching these sources to their counterparts f... | virial black hole mass estimates for 280,000 agns from the sdss broadband photometry and single-epoch spectra |
we used muse adaptive optics data in narrow field mode to study the properties of the ionised gas in mr 2251-178 and pg 1126-041, two nearby (z ≃ 0.06) bright quasars (qsos) hosting sub-pc scale ultra-fast outflows (ufos) detected in the x-ray band. we decomposed the optical emission from diffuse gas into a low- and a ... | galaxy-scale ionised winds driven by ultra-fast outflows in two nearby quasars |
a diverse array of science goals requires accurate flux calibration of observations with the atacama large millimeter/submillimeter array (alma); however, this goal remains challenging due to the stochastic time-variability of the "grid" quasars alma uses for calibration. in this work, we use 343.5 ghz (band 7) alma at... | on the accuracy of the alma flux calibration in the time domain and across spectral windows |
improving our understanding of the nuclear properties of high-eddington-ratio (λedd) active galactic nuclei (agn) is necessary since at this regime the radiation pressure is expected to affect the structure and efficiency of the accretion disc-corona system. this may cause departures from the typical nuclear properties... | x-ray spectroscopic survey of highly accreting agn |
the outstanding mass growth of supermassive black holes (smbhs) at the epoch of reionisation and its relation to the concurrent growth of their host galaxies poses challenges to theoretical models aimed at explaining how these systems formed on short timescales (< 1 gyr). to trace the average evolutionary paths of q... | black hole and host galaxy growth in an isolated z ∼ 6 qso observed with alma |
eight years after the first detection of high-energy astrophysical neutrinos by icecube, we are still almost clueless as regards to their origin, although the case for blazars being neutrino sources is getting stronger. after the first significant association at the $3\!-\!3.5\, \sigma$ level in time and space with ice... | the spectra of icecube neutrino (sin) candidate sources - ii. source characterization |
we investigate the mass structure of a strong gravitational lens galaxy at z = 0.350, taking advantage of the milliarcsecond (mas) angular resolution of very long baseline interferometric (vlbi) observations. in the first analysis of its kind at this resolution, we jointly infer the lens model parameters and pixellated... | a lensed radio jet at milliarcsecond resolution i: bayesian comparison of parametric lens models |
black hole accretion discs can produce powerful outflowing plasma (disc winds), seen as blue-shifted absorption lines in stellar and supermassive systems. these winds in quasars have an essential role in controlling galaxy formation across cosmic time, but there is no consensus on how these are physically launched. a s... | what powers the wind from the black hole accretion disc in gro j1655-40? |
we ask how the inclusion of various physical heating processes due to the metal content of gas affects the evolution of central massive galaxies and compute a suite of cosmological hydrodynamical simulations that follow these systems and their supermassive black holes. we use a smoothed particle hydrodynamics code with... | physics of galactic metals: evolutionary effects due to production, distribution, feedback, and interaction with black holes |
we use the soux sample of ~700 active galactic nucleus (agn) to form average optical-ultraviolet (uv)-x-rays spectral energy distributions (seds) on a two-dimensional (2d) grid of mbh and l2500. we compare these with the predictions of a new agn sed model, qsosed, which includes prescriptions for both hot and warm comp... | the soux agn sample: optical/uv/x-ray seds and the nature of the disc |
the standard λ cold dark matter (λcdm) model is recently reported to deviate from the high-redshift hubble diagram of type ia supernovae (sne) and quasars (qsos) at ~4σ confidence level. in this work, we combine the page approximation (a nearly model-independent parametrization) and a high-quality qso sample to search ... | redshift evolution and non-universal dispersion of quasar luminosity correlation |
we study the rest-frame optical properties of 74 luminous (lbol=1046.2-48.2 erg s-1), 1.5< z< 3.5 broad-line quasars with near-ir (jhk) slit spectroscopy. systemic redshifts based on the peak of the [o iii] λ5007 line reveal that redshift estimates from the rest-frame uv broad emission lines (mostly mg ii) are in... | rest-frame optical properties of luminous 1.5 < z < 3.5 quasars: the hβ-[o iii] region |
celestial objects exhibit a wide range of variability in brightness at different wavebands. surprisingly, the most common methods for characterizing time series in statistics - parametric autoregressive modeling - is rarely used to interpret astronomical light curves. we review standard arma, arima and arfima (autoregr... | autoregressive times series methods for time domain astronomy |
enormous lyα nebulae (elane) represent the extrema of lyα nebulosities. they have detected extents of >200 kpc in lyα and lyα luminosities >1044 erg s-1. the elan population is an ideal laboratory to study the interactions between galaxies and the intergalactic/circumgalactic medium (igm/cgm) given their brightne... | keck/palomar cosmic web imagers reveal an enormous lyα nebula in an extremely overdense quasi-stellar object pair field at z = 2.45 |
relativistic effects in clustering observations have been shown to introduce scale-dependent corrections to the galaxy overdensity field on large scales, which may hamper the detection of primordial non-gaussianity fnl through the scale-dependent halo bias. the amplitude of relativistic corrections depends not only on ... | impact of relativistic effects on the primordial non-gaussianity signature in the large-scale clustering of quasars |
until recently, determining the rotational properties of galaxies in the early universe (z> 4, universe age < 1.5 gyr) was impractical, with the exception of a few strongly lensed systems. combining the high resolution and sensitivity of alma at (sub-)millimeter wavelengths with the typically high strength of the... | dynamical characterization of galaxies at z ∼ 4-6 via tilted ring fitting to alma [c ii] observations |
the existence of axionlike particles (alps) is predicted by many extensions of the standard model of elementary particles and in particular by theories of superstrings and superbranes. alps are very light, neutral, pseudoscalar bosons which are supposed to interact with two photons. they can play an important role in h... | behavior of axionlike particles in smoothed out domainlike magnetic fields |
theory suggests that there are two primary modes of accretion through which dark-matter halos acquire the gas to form and fuel galaxies: hot- and cold-flow accretion. in cold-flow accretion, gas streams along cosmic web filaments to the centre of the halo, allowing for the efficient delivery of star-forming fuel. recen... | multi-filament gas inflows fuelling young star-forming galaxies |
observations of the emission from spatially extended cold gas around bright high-redshift quasars (qsos) reveal surprisingly large velocity widths exceeding 2000 km s- 1, out to projected distances as large as 30 kpc. the high-velocity widths have been interpreted as the signature of powerful agn-driven outflows. naive... | fast cold gas in hot agn outflows. |
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