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we present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the seyfert 1 galaxy ngc 5548. this includes 12 years of new unpublished observations (2003 to 2015). we compiled about 1600 hβ spectra and analyzed the long-term spectral variations of the 5100 å continuum and the hβ line. our analysis ... | evidence for periodicity in 43 year-long monitoring of ngc 5548 |
we present vlt/sinfoni imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z ≳ 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formatio... | the sinfoni survey of powerful radio galaxies at z 2: jet-driven agn feedback during the quasar era |
in preparation for the tomography study of the intergalactic medium (igm) by subaru prime focus spectrograph (pfs) survey and other large future telescopes such as tmt/elt/gmt, we present the results of our pilot study on lyα forest and igm tomography statistics using the gadget3-osaka cosmological smoothed particle hy... | probing feedback via igm tomography and the lyα forest with subaru pfs, tmt/elt, and jwst |
the dominant gaseous structure in the galactic halo is the magellanic stream, an extended network of neutral and ionized filaments surrounding the large and small magellanic clouds (lmc/smc), the two most massive satellite galaxies of the milky way. recent observations indicate that the clouds are on their first passag... | the magellanic corona as the key to the formation of the magellanic stream. |
context. broad emission lines are the most characteristic features in the spectra of galaxies with an active galactic nucleus (agn). they mostly show either single-peaked or double-peaked profiles and originate from a complex dynamics of the likely discrete clouds moving in a spatially extended region known as the broa... | radiation pressure on dust explaining the low ionized broad emission lines in active galactic nuclei. dust as an important driver of line shape |
we present an analysis of the metallicity distribution of the dense circumgalactic medium (cgm) of galaxies at 0.1 ≲ z ≲ 1.1 as probed by partial lyman limit systems (pllss, 16.1 < log {n}{{h}{{i}}} < 17.2) and llss (17.2 ≤ log {n}{{h}{{i}}} < 17.7 in our sample). the new h i-selected sample, drawn from our hu... | low-metallicity absorbers account for half of the dense circumgalactic gas at z ≲ 1 |
we study the sizes of galaxies in the epoch of reionization using a sample of ${\sim 100\, 000}$ galaxies from the bluetides cosmological hydrodynamical simulation from z = 7 to 11. we measure the galaxy sizes from stellar mass and luminosity maps, defining the effective radius as the minimum radius that could enclose ... | the impact of dust on the sizes of galaxies in the epoch of reionization |
we analyse the effect of stochastic torque fluctuations on the orbital evolution and the gravitational wave (gw) emission of gas-embedded sources with intermediate and extreme mass ratios. we show that gas-driven fluctuations imprint additional harmonic content in the gws of the binary system, which we dub dirty wavefo... | dirty waveforms: multiband harmonic content of gas-embedded gravitational wave sources |
we present the goals, design, and first results of the muse ultra deep field (mudf) survey, a large programme using the multi unit spectroscopic explorer (muse) instrument at the eso very large telescope. the mudf survey is collecting ≈150 h on-source of integral field optical spectroscopy in a 1.5 × 1.2 arcmin2 region... | the muse ultra deep field (mudf). ii. survey design and the gaseous properties of galaxy groups at 0.5 < z < 1.5 |
we present the results of an extensive analysis of the optical, ultraviolet, x-ray, and γ-ray data collected from the observations of the bl lac objects prototype bl lacertae carried out over a period of nearly 13 yr, between 2008 august and 2021 march. the source is characterized by strongly variable emission at all f... | a 13-yr-long broad-band view of bl lac |
we report on quasi-periodic variability found in two blazars included in the steward observatory blazar monitoring data sample: the bl lac object 3c 66a and the flat spectrum radio quasar b2 1633+38. we collect optical photometric and polarimetric data in v and r bands of these sources from different observatories: st.... | quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3c 66a and b2 1633+38 |
we present the design, methods, and first results of the muse analysis of gas around galaxies (magg) survey, a large programme on the multi-unit spectroscopic explorer (muse) instrument at the very large telescope (vlt), which targets 28 z > 3.2 quasars to investigate the connection between optically thick gas and g... | muse analysis of gas around galaxies (magg) - i: survey design and the environment of a near pristine gas cloud at z ≈ 3.5 |
pristine, atomically cooled haloes may be the sites of primordial quasar formation because atomic cooling triggers rapid baryon collapse that can create 104-105 m⊙ black hole seeds. however, no numerical simulation has ever followed the collapse of these haloes for the times required to form supermassive stars and dire... | the collapse of atomically cooled primordial haloes - i. high lyman-werner backgrounds |
we report the 888 mhz radio detection in the rapid askap continuum survey (racs) of vik j2318−3113, a z = 6.44 quasar. its radio luminosity (1.2 × 1026 w hz−1 at 5 ghz) compared to the optical luminosity (1.8 × 1024 w hz−1 at 4400 å) makes it the most distant radio-loud quasar observed so far, with a radio loudness r ∼... | radio detection of vik j2318−3113, the most distant radio-loud quasar (z = 6.44) |
we analyse near-infrared integral field spectrograph (nifs) observations of the type-2 quasar (qso2) sdss j094521.33+173753.2 to investigate its warm molecular and ionized gas kinematics. this qso2 has a bolometric luminosity of 1045.7 erg s−1 and a redshift of z = 0.128. the k-band spectra provided by nifs cover a ran... | warm molecular and ionized gas kinematics in the type-2 quasar j0945+1737 |
we present the discovery of the radio-loud quasar pso j352.4034-15.3373 at z = 5.84 ± 0.02. this quasar is the radio brightest source known, by an order of magnitude, at z ∼ 6 with a flux density in the range of 8-100 mjy from 3 ghz to 230 mhz and a radio loudness parameter r={f}ν ,5{ghz}/{f}ν ,4400\mathringa ≳ 1000. t... | a powerful radio-loud quasar at the end of cosmic reionization |
we report the discovery of serenity-18, a galaxy at z ≃ 5.939 for which we could measure the content of molecular gas, m(h2) ≃ 5 × 109 m ⊙, traced by the co(6-5) emission, together with the metal-poor ([fe/h] =-3.08 ± 0.12, [si/h] = -2.86 ± 0.14) gas clump/filament which is possibly feeding its growth. the galaxy has a... | witnessing galaxy assembly at the edge of the reionization epoch |
turbulence in the intracluster, intragroup, and circumgalactic medium plays a crucial role in the self-regulated feeding and feedback loop of central supermassive black holes. we dissect the 3d turbulent 'weather' in a high-resolution eulerian simulation of active galactic nucleus (agn) feedback, shown to be consistent... | dissecting the turbulent weather driven by mechanical agn feedback |
we use herschel 70 to 160 μm images to study the size of the far-infrared emitting region in about 400 local galaxies and quasar (qso) hosts. the sample includes normal "main-sequence" star-forming galaxies, as well as infrared luminous galaxies and palomar-green qsos, with different levels and structures of star forma... | the far-infrared emitting region in local galaxies and qsos: size and scaling relations |
we describe a consequence of the eddington bias which occurs when a single astrophysical neutrino event is used to infer the neutrino flux of the source. a trial factor is introduced by the potentially large number of similar sources that remain undetected; if this factor is not accounted for the luminosity of the obse... | eddington bias for cosmic neutrino sources |
we constrain the average episodic quasar lifetime (as in steady-state accretion) using two statistics of quasars that are recently turned off (i.e., dimmed by a large factor): (1) the fraction of turned-off quasars in a statistical sample photometrically observed over an extended period (e.g., δt = 20 yr) and (2) the f... | extreme variability and episodic lifetime of quasars |
we present a systematic search for periodically varying quasars and supermassive black hole binary (smbhb) candidates in the pan-starrs1 (ps1) medium deep survey’s md09 field. from a color-selected sample of 670 quasars extracted from a multi-band deep-stack catalog of point sources, we locally select variable quasars ... | a systematic search for periodically varying quasars in pan-starrs1: an extended baseline test in medium deep survey field md09 |
we use the combined data from the cos-gass and cos-halos surveys to characterize the circum-galactic medium (cgm) surrounding typical low-redshift galaxies in the mass range {m}* ∼ {10}9.5-11.5 {m}⊙ , and over a range of impact parameters extending to just beyond the halo virial radius (r vir). we find the radial scale... | the properties of the circumgalactic medium in red and blue galaxies: results from the cos-gass+cos-halos surveys |
quasar-driven outflows on galactic scales are a routinely invoked ingredient for galaxy formation models. we report the discovery of ionized gas nebulae surrounding three luminous red quasars at z ~ 0.4 from gemini integral field unit observations. all these nebulae feature unprecedented pairs of "superbubbles" extendi... | discovery of spectacular quasar-driven superbubbles in red quasars |
we study the angular clustering of quaia, a gaia- and unwise-based catalog of over a million quasars with an exceptionally well-defined selection function. with it, we derive cosmology constraints from the amplitude and growth of structure across cosmic time. we divide the sample into two redshift bins, centered at z =... | constraining cosmology with the gaia-unwise quasar catalog and cmb lensing: structure growth |
the origin of the radio emission in radio-quiet quasars (rqq) is not established yet. we present new vlba observations at 1.6 and 4.9 ghz of 10 rqq (9 detected), which together with published earlier observations of 8 rqq (5 detected), forms a representative sample of 18 rqq drawn from the palomar-green sample of low z... | the radio emission in radio-quiet quasars: the vlba perspective |
the continued operation of the wide-field infrared survey explorer (wise), combined with several ground-based optical transient surveys (e.g., crts, asas-sn, and ptf), offers an unprecedented opportunity to explore the dust structures in luminous active galactic nuclei (agns). we use these data for a mid-ir dust reverb... | mid-ir variability and dust reverberation mapping of low-z quasars. i. data, methods, and basic results |
we detected a possible quasi-periodic oscillation (qpo) of ∼71 d in the 0.1-300 gev γ-ray fermi-large area telescope light curve of the high-redshift flat spectrum radio quasar b2 1520+31. we identify and confirm that quasi-period by lomb-scargle periodogram and weighted wavelet z-transform analyses. using this qpo per... | detection of a quasi-periodic oscillation in γ-ray light curve of the high-redshift blazar b2 1520+31 |
context. high-redshift quasars signpost the early accretion history of the universe. the penetrating nature of x-rays enables a less absorption-biased census of the population of these luminous and persistent sources compared to optical/near-infrared colour selection. the ongoing srg/erosita x-ray all-sky survey offers... | first constraints on the agn x-ray luminosity function at z 6 from an erosita-detected quasar |
we investigate the infrared (ir) emission of high-redshift (z ∼ 6), highly star-forming ( ${{\rm sfr}\gt 100\,{\rm m}_{\odot }\, {\rm yr}^{-1}}$ ) galaxies, with/without active galactic nuclei (agn), using a suite of cosmological simulations featuring dust radiative transfer. synthetic spectral energy distributions (se... | infrared emission of z ∼ 6 galaxies: agn imprints |
in this work, we present the first results of the long-term high-cadence spectroscopic monitoring of 15 pg quasars with relatively strong fe ii emission, as a part of a broader reverberation mapping campaign performed using the calar alto observatory's 2.2 m telescope. the v-band, 5100 å continuum, and hβ broad emissio... | supermassive black holes with high accretion rates in active galactic nuclei. xii. reverberation mapping results for 15 pg quasars from a long-duration high-cadence campaign |
we considered the fourth catalog of gamma-ray point sources produced by the fermi large area telescope (lat) and selected only jetted active galactic nuclei (agn) or sources with no specific classification, but with a low-frequency counterpart. our final list is composed of 2980 gamma-ray point sources. we then searche... | a new sample of gamma-ray emitting jetted active galactic nuclei |
quasar broad emission lines are largely powered by photoionization from the accretion continuum. increased central luminosity will enhance line emissivity in more distant clouds, leading to increased average distance of the broad-line-emitting clouds and decreased averaged line width, which is known as the "breathing" ... | the sloan digital sky survey reverberation mapping project: how broad emission line widths change when luminosity changes |
using blazar light curves from the optical all-sky automated survey for supernovae (asas-sn) and the γ-ray fermi-lat telescope, we performed the most extensive statistical correlation study between both bands, using a sample of 1180 blazars. this is almost an order of magnitude larger than other recent studies. blazars... | optical/γ-ray blazar flare correlations: understanding the high-energy emission process using asas-sn and fermi light curves |
the recent evidence of a stochastic background of gravitational waves in the nhz band by pulsar timing array (pta) experiments has shed new light on the formation and evolution of massive black hole binaries with masses ∼108- 109m⊙ . the pta data are consistent with a population of such binaries merging efficiently aft... | implications of the pulsar timing array detections for massive black hole mergers in the lisa band |
recent studies have suggested that red quasars are a phase in quasar evolution when feedback from black hole accretion evacuates obscuring gas from the nucleus of the host galaxy. here, we report a direct link between dust-reddening and molecular outflows in quasars at z ~ 2.5. by examining the dynamics of warm molecul... | red quasars blow out molecular gas from galaxies during the peak of cosmic star formation |
context. the most highly accreting quasars are of special interest in studies of the physics of active galactic nuclei (agns) and host galaxy evolution. quasars accreting at high rates (l/ledd ∼ 1) hold promise for use as "standard candles": distance indicators detectable at very high redshift. however, their observati... | highly accreting quasars: the sdss low-redshift catalog |
we investigate the multi-wavelength properties of host galaxies of 3701 x-ray-selected active galactic nuclei (agns) out to z ∼ 5 in the chandra-cosmos legacy survey. thanks to the extensive multi-wavelength photometry available in the cosmos field, we derive agn luminosities, host stellar masses, and star formation ra... | multi-wavelength properties of type 1 and type 2 agn host galaxies in the chandra-cosmos legacy survey |
we present the first systematic study of 50 low-redshift (0.66 < z < 1.63) iron low-ionization broad absorption-line quasars (felobalqs) using simbal, which represents a more than five-fold increase in the number of felobalqs with detailed absorption line spectral analyses. we found the outflows have a wide range... | the physical properties of low-redshift felobal quasars. i. spectral-synthesis analysis of the broad absorption-line (bal) outflows using simbal |
context. galaxy evolution scenarios predict that the feedback of star formation and nuclear activity (agn) can drive the transformation of gas-rich spiral mergers into (ultra) luminous infrared galaxies and, eventually, lead to the build-up of qso/elliptical hosts.aims: we study the role that star formation and agn fee... | high-resolution imaging of the molecular outflows in two mergers: iras 17208-0014 and ngc 1614 |
the cosmological process of hydrogen (h i) reionization in the intergalactic medium is thought to be driven by uv photons emitted by star-forming galaxies and ionizing active galactic nuclei (agn). the contribution of quasars (qsos) to h i reionization at z > 4 has been traditionally believed to be quite modest. how... | constraining the uv emissivity of agn throughout cosmic time via x-ray surveys |
recent results have suggested that active galactic nuclei (agn) could provide enough photons to reionize the universe. we assess the viability of this scenario using a semi-numerical framework for modelling reionization, to which we add a quasar contribution by constructing a quasar halo occupancy distribution (qhod) b... | constraining the contribution of active galactic nuclei to reionization |
gaia’s precision astrometry allows systematic identification of optically selected subkiloparsec dual active galactic nuclei (agns), off-nucleus agns, and small-scale lensed quasars by “varstrometry”—where variability-induced astrometric jitter, i.e., temporal displacements of photocenter in unresolved sources, can be ... | varstrometry for off-nucleus and dual subkiloparsec agn (vodka): methodology and initial results with gaia dr2 |
very long baseline interferometry (vlbi) from the ground at millimeter wavelengths can resolve the black hole shadow around two supermassive black holes, sagittarius a∗ and m87. the addition of modest telescopes in space would allow the combined array to produce higher-resolution, higher-fidelity images of these and ot... | imaging black holes and jets with a vlbi array including multiple space-based telescopes |
intermediate-mass black holes (imbhs; masses between 100{ and }106 m_{\odot }) historically comprise of an elusive population compared to stellar-mass and supermassive black holes (bhs). recently, imbhs have started to be observed at the centres of low-mass galaxies. we perform cosmological hydrodynamical simulations o... | intermediate-mass black hole growth and feedback in dwarf galaxies at high redshifts |
heavily obscured, compton thick (ct, nh> 1024 cm-2) active galactic nuclei (agn) may represent an important phase in agn/galaxy co-evolution and are expected to provide a significant contribution to the cosmic x-ray background at its peak. however, unambiguously identifying ct agn beyond the local universe is a chal... | compton thick agn in the xmm-cosmos survey |
we present the infrared (ir) and x-ray properties of a sample of 33 mid-ir luminous quasars (νl6 μm ≥ 6 × 1044 erg s-1) at redshift z ≈ 1-3, identified through detailed spectral energy distribution analyses of distant star-forming galaxies, using the deepest ir data from spitzer and herschel in the goods-herschel field... | mid-infrared luminous quasars in the goods-herschel fields: a large population of heavily obscured, compton-thick quasars at z ≈ 2 |
to study the impact of active galactic nuclei (agn) feedback on their galactic ism, we present magellan long-slit spectroscopy of 12 luminous nearby obscured agn ({l}{bol}∼ {10}45.0-46.5 {erg} {{{s}}}-1, z ∼ 0.1). these objects are selected from a parent sample of spectroscopically identified agn to have high [o iii]λ5... | sizes and kinematics of extended narrow-line regions in luminous obscured agn selected by broadband images |
we use the sherwood-relics suite of hybrid hydrodynamical and radiative transfer simulations to model the effect of inhomogeneous reionization on the 1d power spectrum of the lyman α (lyα) forest transmitted flux at redshifts 4.2 ≤ z ≤ 5. relative to models that assume a homogeneous ultraviolet background, reionization... | the effect of inhomogeneous reionization on the lyman α forest power spectrum at redshift z > 4: implications for thermal parameter recovery |
context. the detection of quasi-periodic oscillations (qpos) in the light curves of active galactic nuclei (agns) can provide insights into the physics of the super-massive black holes (smbhs) powering these systems and could represent a signature of the existence of smbh binaries, setting fundamental constraints on sm... | quasi-periodic oscillations in the γ-ray light curves of bright active galactic nuclei |
mildly relativistic shocks that are embedded in colliding magnetohydrodynamic flows are prime sites for relativistic particle acceleration and the production of strongly variable, polarized multi-wavelength emission from relativistic jet sources such as blazars and gamma-ray bursts. the principal energization mechanism... | multi-wavelength variability signatures of relativistic shocks in blazar jets |
we present a new measurement of the lyα forest power spectrum at 1.8 < z < 3.4 using 74 keck/hires and vlt/uves high-resolution, high-signal-to-noise-ratio quasar spectra. we developed a custom pipeline to measure the power spectrum and its uncertainty, which fully accounts for finite resolution and noise and cor... | a new precision measurement of the small-scale line-of-sight power spectrum of the lyα forest |
it has been known for over three decades that the monochromatic x-ray and uv luminosities in quasars are correlated, though non-linearly. this offers the possibility of using high-z quasars as standard candles for cosmological testing. in this paper, we use a recently assembled, high-quality catalogue of 1598 quasars e... | cosmological test using the hubble diagram of high-z quasars |
we present and make publicly available the first data release (dr1) of the keck observatory database of ionized absorption toward quasars (kodiaq) survey. the kodiaq survey is aimed at studying galactic and circumgalactic gas in absorption at high redshift, with a focus on highly ionized gas traced by o vi, using the h... | the first data release of the kodiaq survey |
we report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the sdss-iii baryon oscillation spectroscopic survey (boss). we adopted a methodology similar to that used in the sdss quasar lens search (sqls). in addition to the confirmed lenses, we report ... | the sdss-iii boss quasar lens survey: discovery of 13 gravitationally lensed quasars |
we present qsfit (quasar spectral fitting package), a new software package to automatically perform the analysis of active galactic nuclei (agns) optical spectra. the software provides luminosity estimates for the agn continuum, the balmer continuum, both optical and ultraviolet iron blended complex, host galaxy and em... | qsfit: automatic analysis of optical agn spectra |
we study the multiphase feedback processes in the central ∼3 kpc of the barred seyfert 2 galaxy ngc 5643. we used observations of the cold molecular gas (alma co(2-1) transition) and ionized gas (muse ifu optical emission lines). we studied different regions along the outflow zone, which extends out to ∼2.3 kpc in the ... | multiphase feedback processes in the sy2 galaxy ngc 5643 |
the first generation of galaxies is expected to form in minihaloes, accreting gas through h2 cooling, and possessing unique properties. although unlikely to be directly detected in uv/infrared surveys, the radiation from these molecular-cooling galaxies (mcgs) could leave an imprint in the 21-cm signal from the cosmic ... | a tale of two sites - ii. inferring the properties of minihalo-hosted galaxies with upcoming 21-cm interferometers |
context. agn outflows are thought to influence the evolution of their host galaxies and of super massive black holes. our deep multiwavelength campaign on ngc 5548 has revealed a new, unusually strong x-ray obscuration, accompanied by broad uv absorption troughs observed for the first time in this object. the x-ray obs... | anatomy of the agn in ngc 5548. ii. the spatial, temporal, and physical nature of the outflow from hst/cos observations |
we report on the search for galaxies in the proximity of two very metal-poor gas clouds at z ∼ 3 towards the quasar q0956+122. with a 5-hour multi-unit spectroscopic explorer (muse) integration in a ∼500 × 500 kpc2 region centred at the quasar position, we achieve a ≥80 per cent complete spectroscopic survey of continu... | muse searches for galaxies near very metal-poor gas clouds at z ∼ 3: new constraints for cold accretion models |
we present a detailed analysis of a large-scale galactic outflow in the circumgalactic medium of a massive ({m}{{h}}∼ {10}12.5 {m}⊙ ), star-forming (∼ 6.9 {m}⊙yr-1), sub-l* (∼ 0.5{l}b*) galaxy at z = 0.39853 that exhibits a wealth of metal-line absorption in the spectra of the background quasar q 0122-003 at an impact ... | an extreme metallicity, large-scale outflow from a star-forming galaxy at z ~ 0.4 |
most active galactic nuclei (agns) are radio quiet, and the origin of their radio emission is not well understood. one hypothesis is that this radio emission is a byproduct of quasar-driven winds. in this paper, we present the radio properties of 108 extremely red quasars (erqs) at z = 2-4. erqs are among the most lumi... | winds as the origin of radio emission in z = 2.5 radio-quiet extremely red quasars |
the origin of the radio emission in radio-quiet (rq) quasars is not established yet. important hints can be provided by the spectral slope, and its relation to other emission properties. we compiled the highest resolution 5 and 8.4 ghz very large array observations available of the rq optically selected palomar-green (... | what drives the radio slopes in radio-quiet quasars? |
off-nucleus active galactic nuclei (agn) can be signposts of inspiraling supermassive black holes (smbhs) on galactic scales, or accreting smbhs recoiling after the coalescence of an smbh binary or slingshot from three-body interactions. because of the stochastic variability of agn, the measured photocenter of an unres... | varstrometry for off-nucleus and dual sub-kpc agn (vodka): how well centered are low-z agn? |
the 4most cosmology redshift survey (crs) will perform stringent cosmological tests via spectroscopic clustering measurements that will complement the best lensing, cosmic microwave background and other surveys in the southern hemisphere. the combination of carefully selected samples of bright galaxies, luminous red ga... | 4most consortium survey 8: cosmology redshift survey (crs) |
here we present the spectropolarimetric observations of a sample of 30 type 1 active galactic nuclei (agns) and an analysis of the observed polarization in these agns. the observations have been performed with the 6 m telescope of sao ras using the modified scorpio-2 spectropolarimeter. we measured the stokes parameter... | spectropolarimetry of seyfert 1 galaxies with equatorial scattering: black hole masses and broad-line region characteristics |
we present a markov chain monte carlo (mcmc)-based parameter estimation package, cosmoreionmc, to jointly constrain cosmological parameters of the lambda cold dark matter (λcdm) model and the astrophysical parameters related to hydrogen reionization. the package is based on a previously developed physically motivated s... | cosmoreionmc: a package for estimating cosmological and astrophysical parameters using cmb, lyman-α absorption, and global 21 cm data |
the epoch of reionization (eor) depends on the complex astrophysics governing the birth and evolution of the first galaxies and structures in the intergalactic medium. eor models rely on cosmic microwave background (cmb) observations, and in particular the large-scale e-mode polarization power spectra (ee ps), to help ... | reionization inference from the cmb optical depth and e-mode polarization power spectra |
we study the mass assembly and spin evolution of supermassive black holes (bhs) across cosmic time as well as the impact of gravitational recoil on the population of nuclear and wandering bhs (wbhs) by using the semi-analytical model l-galaxies run on top of millennium merger trees. we track spin changes that bhs exper... | from galactic nuclei to the halo outskirts: tracing supermassive black holes across cosmic history and environments |
we have recently used the faint images of the radio sky at twenty-centimeters (first) survey to show that red quasars have fundamentally different radio properties to typical blue quasars: a significant (factor ≈3) enhancement in the radio-detection fraction, which arises from systems around the radio-quiet threshold w... | fundamental differences in the radio properties of red and blue quasars: enhanced compact agn emission in red quasars |
quasars whose broad emission lines show temporal, bulk radial velocity (rv) shifts have been proposed as candidate sub-parsec (sub-pc), binary supermassive black holes (bsbhs). we identified a sample of 16 bsbh candidates based on two-epoch spectroscopy among 52 quasars with significant rv shifts over a few rest-frame ... | constraining sub-parsec binary supermassive black holes in quasars with multi-epoch spectroscopy - iii. candidates from continued radial velocity tests |
in this paper, the multiwavelength data from radio to x-ray bands for 2709 blazars in the 4fgl-dr3 catalog are compiled to calculate their spectral energy distributions using a parabolic equation $\mathrm{log}(\nu {f}_{\nu })={p}_{1}{\left(\mathrm{log}\nu -{p}_{2}\right)}^{2}+{p}_{3}$ . some important parameters includ... | the spectral energy distributions for 4fgl blazars |
the vera c. rubin observatory's legacy survey of space and time (lsst) will detect an unprecedentedly large sample of actively accreting supermassive black holes with typical accretion disk (ad) sizes of a few light days. this brings us to face challenges in the reverberation mapping (rm) measurement of ad sizes in act... | the lsst era of supermassive black hole accretion disk reverberation mapping |
we present the discovery of pso j083.8371+11.8482, a weak emission line quasar with extreme star formation rate at z = 6.3401. this quasar was selected from pan-starrs1, uhs, and unwise photometric data. gemini/gnirs spectroscopy follow-up indicates a mg ii-based black hole mass of ${m}_{\mathrm{bh}}=\left({2.0}_{-0.4}... | probing the nature of high-redshift weak emission line quasars: a young quasar with a starburst host galaxy |
the statistics of galactic-scale quasar pairs can elucidate our understanding of the dynamical evolution of supermassive black hole (smbh) pairs, the duty cycles of quasar activity in mergers, or even the nature of dark matter, but they have been challenging to measure at cosmic noon, the prime epoch of massive galaxy ... | statistics of galactic-scale quasar pairs at cosmic noon |
the study of the properties of galaxies in the first billion years after the big bang is one of the major topics of current astrophysics. optical and near-infrared spectroscopy of the afterglows of long gamma-ray bursts (grbs) provides a powerful diagnostic tool to probe the interstellar medium (ism) of their host gala... | dissecting the interstellar medium of a z = 6.3 galaxy. x-shooter spectroscopy and hst imaging of the afterglow and environment of the swift grb 210905a |
recent x-ray observations have revealed remarkable correlations between the masses of central supermassive black holes (smbhs) and the x-ray properties of the hot atmospheres permeating their host galaxies, thereby indicating the crucial role of the atmospheric gas in tracing smbh growth in the high-mass regime. we exa... | correlations between supermassive black holes and hot gas atmospheres in illustristng and x-ray observations |
using moderate-resolution optical spectra from 58 background lyman-break galaxies and quasars at z∼ 2.3{{{--}}}3 within a 11.‧5 × 13.‧5 area of the cosmos field (∼ 1200 {{deg}}-2 projected area density or ∼ 2.4 {h}-1mpc mean transverse separation), we reconstruct a 3d tomographic map of the foreground lyα forest absorp... | shadow of a colossus: a z = 2.44 galaxy protocluster detected in 3d lyα forest tomographic mapping of the cosmos field |
we analyze differences in positions of active galactic nuclei (agns) between gaia data release 2 and very long baseline interferometry (vlbi) and compare the significant vlbi-to-gaia offsets in more than 1000 objects with their jet directions. remarkably at least three-fourths of the significant offsets are confirmed t... | dissecting the agn disk-jet system with joint vlbi-gaia analysis |
based on constraints from big bang nucleosynthesis and the cosmic microwave background, the baryon content of the high-redshift universe can be precisely determined. however, at low redshift, about one-third of the baryons remain unaccounted for, which poses the long-standing missing baryon problem. the missing baryons... | detection of the missing baryons toward the sightline of h1821+643 |
we investigate the large-scale structure of lyα emission intensity in the universe at redshifts z = 2-3.5 using cross-correlation techniques. our lyα emission samples are spectra of boss luminous red galaxies from data release 12 with the best-fitting model galaxies subtracted. we cross-correlate the residual flux in t... | intensity mapping with sdss/boss lyman-α emission, quasars, and their lyman-α forest |
in this paper, we present the long-term optical spectral monitoring of a changing-look active galactic nucleus (agn), ngc 3516, covering 22 yr (from 1996 to 2018). we explore a variability in the broad lines and continuum, finding that the continuum is changing by more than a factor of 2, while the broad lines are vary... | long-term optical spectral monitoring of a changing-look active galactic nucleus ngc 3516 - i. continuum and broad-line flux variability |
aims: the co-evolution of galaxies and supermassive black holes (smbhs) requires that some sort of feedback mechanism is operating during the active galactic nuclei (agn) phases. agn driven winds are the most likely candidates for such feedback mechanism, but direct observational evidence of their existence and of thei... | galaxy-wide outflows in z ~ 1.5 luminous obscured quasars revealed through near-ir slit-resolved spectroscopy |
we report a bimodality in the azimuthal angle (φ) distribution of gas around galaxies traced by o vi absorption. we present the mean φ probability distribution function of 29 hubble space telescope-imaged o vi absorbing (ew > 0.1 å) and 24 non-absorbing (ew < 0.1 å) isolated galaxies (0.08 \lt z \lt 0.67) within ... | the azimuthal dependence of outflows and accretion detected using o vi absorption |
multiwavelength surveys covering large sky volumes are necessary to obtain an accurate census of rare objects such as high-luminosity and/or high-redshift active galactic nuclei (agns). stripe 82x is a 31.3 x-ray survey with chandra and xmm-newton observations overlapping the legacy sloan digital sky survey stripe 82 f... | agn populations in large-volume x-ray surveys: photometric redshifts and population types found in the stripe 82x survey |
context. over the past few years, on several occasions, large, continuous rotations of the electric vector position angle (evpa) of linearly polarized optical emission from blazars have been reported. these events are often coincident with high energy γ-ray flares and they have attracted considerable attention, since t... | polarization angle swings in blazars: the case of 3c 279 |
the qubrics (quasars as bright beacons for cosmology in the southern hemisphere) survey aims at constructing a sample of the brightest quasars with $z \lower.5ex\hbox{$\,\, \buildrel\gt \over \sim \,\,$}2.5$, observable with facilities in the southern hemisphere. qubrics makes use of the available optical and ir wide-f... | spectroscopy of qubrics quasar candidates: 1672 new redshifts and a golden sample for the sandage test of the redshift drift |
the flat-spectrum radio quasar cta 102 experienced a prolonged state of enhanced activity across the entire observed electromagnetic spectrum during 2016-2017, most pronounced during a major outburst between 2016 december and 2017 may. fermi-lat observed a flux of (2.2 ± 0.2) × 10-5 photons cm-2 s-1 at energies above 1... | short-timescale γ-ray variability in cta 102 |
the specifics of how galaxies form from, and are fuelled by, gas from the intergalactic medium remain uncertain. hydrodynamic simulations suggest that `cold accretion flows'--relatively cool (temperatures of the order of 104 kelvin), unshocked gas streaming along filaments of the cosmic web into dark-matter halos--are ... | a giant protogalactic disk linked to the cosmic web |
upcoming ultrahigh power lasers at 10 pw level will make it possible to experimentally explore electron-positron (e-e+) pair cascades and subsequent relativistic e-e+ jets formation, which are supposed to occur in extreme astrophysical environments, such as black holes, pulsars, quasars and gamma-ray bursts. in the lat... | qed cascade saturation in extreme high fields |
recent measurements of the parameters of the concordance cosmology model ($\lambda$cdm) done in the low-redshift universe with supernovae ia/cepheids, and in the distant universe done with cosmic microwave background (cmb) imply different values for the hubble constant (67.4 $\pm$ 0.5 km s$^{-1}$ mpc$^{-1}$ from planck... | dark energy constraintsfrom quasar observations |
we proposed a model-independent method to constrain cosmological parameters using the distance sum rule of the friedmann-lemaître-robertson-walker metric by combining the time delay distances and the comoving distances through a multi-messenger approach. the time delay distances are measured from lensed gravitational w... | constraining cosmological parameters in the flrw metric with lensed gw+em signals |
theoretical models of galaxy formation suggest that the presence of an active galactic nucleus (agn) is required to regulate the growth of its host galaxy through feedback mechanisms, produced by, for example, agn-driven outflows. although many observational studies have revealed that such outflows are common both at l... | super. i. toward an unbiased study of ionized outflows in z ∼ 2 active galactic nuclei: survey overview and sample characterization |
using parallaxes from gaia data release 2 (gaia dr2), we estimate the distance to the globular clusters 47 tuc and ngc 362, taking advantage of the background stars in the small magellanic cloud and quasars to account for various parallax systematics. we found the parallax to be dependent on the gaia dr2 g-band apparen... | distances to the globular clusters 47 tucanae and ngc 362 using gaia dr2 parallaxes |
we report the discovery, spectroscopic confirmation, and first lens models of the first, strongly lensed quasars from a combined search in wise and gaia-dr1 over the des footprint. their einstein radii span a range between ≈2.0 arcsec and ≈0.4 arcsec. two of these (wgd2038-4008, ra = 20:38:02.65, dec. = -40:08:14.64; w... | des meets gaia: discovery of strongly lensed quasars from a multiplet search |
we review the reports of possible year-long quasi-periodicities of bl lac objects in the γ-ray and optical bands, and present a homogeneous time analysis of the light curves of pks2155-304, pg1553+113, and bl lac. based on results from a survey covering the entire fermi γ-ray sky we have estimated the fraction of possi... | quasi-periodicities of bl lacertae objects |
we present the discovery of two z > 6 quasars, selected as i-band dropouts in the very large telescope survey telescope atlas survey. our first quasar has redshift, z = 6.31 ± 0.03, z-band magnitude, zab = 19.63 ± 0.08 and rest frame 1450 å absolute magnitude, m1450 = -27.8 ± 0.2, making it the joint second most lum... | two bright z > 6 quasars from vst atlas and a new method of optical plus mid-infrared colour selection. |
high-redshift quasars are believed to reside in highly biased regions of the universe, where black hole growth is sustained by an enhanced number of mergers and by being at the intersection of filaments bringing fresh gas. this assumption should be supported by an enhancement of the number counts of galaxies in the fie... | the diverse galaxy counts in the environment of high-redshift massive black holes in horizon-agn |
accretion states, which are universally observed in stellar mass black holes in x-ray binaries, might be expected in active galactic nuclei (agn). this is the case at low luminosities, when the jet-corona coupling dominates the energy output in both populations. previous attempts to extend this framework to a wider agn... | x-ray binary accretion states in active galactic nuclei? sensing the accretion disc of supermassive black holes with mid-infrared nebular lines |
we present a comprehensive analysis of all xmm-newton spectra of oj 287 spanning 15 yr of x-ray spectroscopy of this bright blazar. we also report the latest results from our dedicated swift uvot and xrt monitoring of oj 287, which started in 2015, along with all earlier public swift data since 2005. during this time i... | x-ray spectral components of the blazar and binary black hole candidate oj 287 (2005-2020) |
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