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we have developed a parallel code called the voigt profile parameter estimation routine (viper) for automatically fitting the h i lyα forest seen in the spectra of quasi-stellar objects (qsos). we obtained the h i column density distribution function (cddf) and linewidth (b) parameter distribution for z < 0.45 using... | voigt profile parameter estimation routine (viper): h i photoionization rate at z < 0.5 |
during the peak of their accretion phase, supermassive black holes in galactic cores are known to emit very high levels of ionizing radiation, becoming visible over intergalactic distances as quasars or active galactic nuclei (agn). here, we quantify the extent to which the activity of the supermassive black hole at th... | the habitability of the milky way during the active phase of its central supermassive black hole |
we have observed 104 gravitationally lensed quasars at z ∼ 1-4 with herschel/spire, the largest such sample ever studied. by targeting gravitational lenses, we probe intrinsic far-infrared (fir) luminosities and star formation rates (sfrs) more typical of the population than the extremely luminous sources that are othe... | gravitational lensing reveals extreme dust-obscured star formation in quasar host galaxies |
even with several thousand fermi-large area telescope (lat) blazar detections, the γ-ray emission mechanism is poorly understood. we explore correlated optical/γ-ray flux variations for 178 fermi-lat blazars regularly monitored by the katzman automatic imaging telescope, the small and moderate aperture research telesco... | probing blazar emission processes with optical/gamma-ray flare correlations |
in order to better understand how active galactic nuclei (agns) affect the interstellar media of their host galaxies, we perform a meta-analysis of the co emission for a sample of z = 0.01-4 galaxies from the literature with existing co detections and well-constrained agn contributions to the infrared (67 galaxies). us... | co emission in infrared-selected active galactic nuclei |
we present the discovery of a very hot gas phase of the milky way circumgalactic medium (cgm) at t ≈ 107 k, using deep xmm-newton reflection grating spectrometer observations of the blazar 1es 1553+113. the hot gas, coexisting with a warm-hot phase at t ≈ 106 k is α-enhanced, with [{{o}}/{fe}]={0.9}-0.3+0.7, indicating... | discovery of a very hot phase of the milky way circumgalactic medium with non-solar abundance ratios |
galaxy evolution is thought to be driven in large part by the flow of gas between galaxies and the circumgalactic medium (cgm), a halo of metal-enriched gas extending out to ≳100 kpc from each galaxy. studying the spatial structure of the cgm holds promise for understanding these gas flow mechanisms; however, the commo... | kinematics of the circumgalactic medium of a z = 0.77 galaxy from mg ii tomography |
recently, it was shown that quark matter with only u and d quarks (u d qm ) can be the ground state of matter for baryon numbers a >amin with amin≳300 . in this paper, we explore u d quark stars (u d qss ) that are composed of u d qm , in the context of the two-families scenario in which u d qss and hadronic stars (... | probing up-down quark matter via gravitational waves |
at redshifts of z ≲ 1.3, early-type galaxies (etgs) and passive galaxies are mainly found in dense environments, such as galaxy clusters. however, it remains unclear whether these well-known morphology-density and passive-density relations have already been established at higher redshifts. to address this question, we ... | morphology-density relation, quenching, and mergers in carla clusters and protoclusters at 1.4 < z < 2.8 |
combining the exquisite angular resolution of gaia with optical light curves and wise photometry, the gaia gravitational lenses group (gral) uses machine-learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars from the gaia data release 2. this pap... | gaia gral: gaia dr2 gravitational lens systems. vi. spectroscopic confirmation and modeling of quadruply imaged lensed quasars |
to understand the active galactic nuclei (agns) phenomenon and their impact on the evolution of galaxies, a complete agn census is required; however, finding heavily obscured agns is observationally challenging. here we use the deep and extensive multiwavelength data in the cosmos field to select a complete sample of 5... | a panchromatic view of infrared quasars: excess star formation and radio emission in the most heavily obscured systems |
we present the first full catalog and science results for the nuclear spectroscopic telescope array (nustar) serendipitous survey. the catalog incorporates data taken during the first 40 months of nustar operation, which provide ≈20 ms of effective exposure time over 331 fields, with an areal coverage of 13 deg2, and 4... | the nustar serendipitous survey: the 40-month catalog and the properties of the distant high-energy x-ray source population |
we present the results of our alma observations of three active galactic nucleus (agn)-dominated nuclei in optical seyfert 1 galaxies (ngc 7469, i zw 1, and ic 4329 a) and eleven luminous infrared galaxies (lirgs) with various levels of infrared estimated energetic contributions by agns at the hcn and hco+ j = 3 - 2 em... | alma hcn and hco+ j =3-2 observations of optical seyfert and luminous infrared galaxies: confirmation of elevated hcn-to-hco+ flux ratios in agns |
as part of the megamaser cosmology project, we present vlbi maps of nuclear water masers toward five galaxies. the masers originate in sub-parsec circumnuclear disks. for three of the galaxies, we fit keplerian rotation curves to estimate their supermassive black hole (smbh) masses, and determine (2.9 ± 0.3) × 106 m⊙ f... | the megamaser cosmology project. ix. black hole masses for three maser galaxies |
we utilize the multi unit spectroscopic explorer (muse) on the very large telescope to search for extended lyα emission around the z ∼ 6.6 qso j0305-3150. after carefully subtracting the point spread function, we reach a nominal 5σ surface-brightness limit of sb5σ= 1.9 × 10-18 erg s-1 cm-2 arcsec-2 over a 1 arcsec2 ape... | mapping the lyα emission around a z ∼ 6.6 qso with muse: extended emission and a companion at a close separation |
we analysed the parsec-scale linear polarization properties of 436 active galactic nuclei (agns) based on 15 ghz polarimetric very long baseline array observations. we present polarization and total intensity images averaged over at least five epochs since 1996 january 19 through 2019 august 4. stacking improves the im... | mojave - xx. persistent linear polarization structure in parsec-scale agn jets |
two groups of astronomers used the large telescopes keck and vlt for decades to observe trajectories of bright stars near the galactic centre. based on results of their observations, the astronomers concluded that trajectories of the stars are roughly elliptical and foci of the orbits are approximately coincide with th... | testing the galactic centre potential with s-stars |
the quest for extrasolar planets and their characterisation as well as studies of fundamental physics on cosmological scales rely on capabilities of high-resolution astronomical spectroscopy. a central requirement is a precise wavelength calibration of astronomical spectrographs allowing for extraction of subtle wavele... | broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb |
the expected level of γγ absorption in the broad line region (blr) radiation field of γ-ray loud flat spectrum radio quasars (fsrqs) is evaluated as a function of the location of the γ-ray emission region. this is done self-consistently with parameters inferred from the shape of the spectral energy distribution (sed) i... | gamma-gamma absorption in the broad line region radiation fields of gamma-ray blazars |
we present results from deep observations toward the cygnus region using 300 hr of very high energy (vhe) γ-ray data taken with the veritas cerenkov telescope array and over 7 yr of high-energy γ-ray data taken with the fermi satellite at an energy above 1 gev. as the brightest region of diffuse γ-ray emission in the n... | a very high energy γ-ray survey toward the cygnus region of the galaxy |
we present a neutral hydrogen-selected absorption-line survey of gas with h i column densities 15< {log}{n}{{h}{{i}}}< 19 at z≲ 1 using the cosmic origins spectrograph on the hubble space telescope. our main aim is to determine the metallicity distribution of these absorbers. our sample consists of 224 absorbers ... | the cos cgm compendium. i. survey design and initial results |
changing-look active galactic nuclei (cl-agns) as a new subpopulation challenge some fundamental physics of agns because the timescales of the phenomenon can hardly be reconciled with accretion disk models. in this letter, we demonstrate the extreme case: close binaries of supermassive black holes (cb-smbhs) with high ... | changing-look active galactic nuclei: close binaries of supermassive black holes in action |
coalescing, massive black-hole (mbh) binaries are the most powerful sources of gravitational waves (gws) in the universe, which makes mbh science a prime focus for ongoing and upcoming gw observatories. the laser interferometer space antenna (lisa) -- a gigameter scale space-based gw observatory -- will grant us access... | astro2020 science white paper: the gravitational wave view of massive black holes |
we report on an observation of the galactic black hole candidate grs 1739-278 during its 2014 outburst, obtained with nustar. the source was captured at the peak of a rising "low/hard" state, at a flux of ~0.3 crab. a broad, skewed iron line and disk reflection spectrum are revealed. fits to the sensitive nustar spectr... | new constraints on the black hole low/hard state inner accretion flow with nustar |
we present results from a survey designed to probe the star formation properties of 32 damped lyman α systems (dlas) at z ∼ 2.7. by using the `double-dla' technique that eliminates the glare of the bright background quasars, we directly measure the rest-frame far-ultraviolet flux from dlas and their neighbouring galaxi... | directly imaging damped ly α galaxies at z > 2 - iii. the star formation rates of neutral gas reservoirs at z ∼ 2.7 |
using two-dimensional radiation hydrodynamic simulations, we investigate the origin of the ultra-fast outflows (ufos) that are often observed in luminous active galactic nuclei (agns). we found that the radiation force due to the spectral lines generates strong winds (line-driven disk winds) that are launched from the ... | radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows |
magnetic penrose process (mpp) is not only the most exciting and fascinating process mining the rotational energy of black hole but it is also the favored astrophysically viable mechanism for high energy sources and phenomena. it operates in three regimes of efficiency, namely low, moderate and ultra, depending on the ... | fifty years of energy extraction from rotating black hole: revisiting magnetic penrose process |
different massive black hole mass - host galaxy scaling relations suggest that the growth of massive black holes is entangled with the evolution of their host galaxies. the number of measured black hole masses is still limited and additional measurements are necessary to understand the underlying physics of this appare... | six new supermassive black hole mass determinations from adaptive-optics assisted sinfoni observations |
it is not yet clear what triggers the activity of active galactic nuclei (agns), but galaxy merging has been suspected to be one of the main mechanisms fueling the activity. using deep optical images taken at various ground-based telescopes, we investigate the fraction of galaxy mergers in 39 luminous agns (mr ≲ -22.6 ... | correlation between galaxy mergers and luminous active galactic nuclei |
gravitational lens flux-ratio anomalies provide a powerful technique for measuring dark matter substructure in distant galaxies. however, before using these flux-ratio anomalies to test galaxy formation models, it is imperative to ascertain that the given anomalies are indeed due to the presence of dark matter substruc... | sharp - ii. mass structure in strong lenses is not necessarily dark matter substructure: a flux ratio anomaly from an edge-on disc in b1555+375 |
we present and make publicly available the second data release (dr2) of the keck observatory database of ionized absorption toward quasars (kodiaq) survey. kodiaq dr2 consists of a fully reduced sample of 300 quasars at 0.07< {z}{em}< 5.29 observed with hires at high resolution (36,000 ≤ r ≤ 103,000). dr2 contain... | the second data release of the kodiaq survey |
the existence of luminous quasars (qsos) at the epoch of reionization (eor; i.e., z > 6) powered by well-grown supermassive black holes (smbhs) with masses ≳109 m⊙ challenges models of early smbh formation and growth. to shed light on the nature of these sources, we started a multiwavelength program based on a sampl... | hyperluminous quasars at the epoch of reionization (hyperion): a new regime for the x-ray nuclear properties of the first quasars |
we present xmm-newton x-ray observations and analysis of three dark energy survey z > 6.5 quasars (vdes j0020-3653 at z = 6.824, vdes j0244-5008 at z = 6.724, and vdes j0224-4711 at z = 6.526) and six other quasars with 6.438 < z < 6.747 from the xmm-newton public archive. two of the nine quasars are detected ... | x-ray properties of z ≳ 6.5 quasars |
we study the x-ray variability properties of distant active galactic nuclei (agns) in the chandradeep field-south region over 17 yr, up to z ∼ 4, and compare them with those predicted by models based on local samples. we use the results of monte carlo simulations to account for the biases introduced by the discontinuou... | tracing the accretion history of supermassive black holes through x-ray variability: results from the chandradeep field-south |
we use the eagle cosmological, hydrodynamical simulations to predict the column density and equivalent width distributions of intergalactic o vii (e=574 {ev}) and o viii (e=654 {ev}) absorbers at low redshift. these two ions are predicted to account for 40 per cent of the gas-phase oxygen, which implies that they are k... | the abundance and physical properties of o vii and o viii x-ray absorption systems in the eagle simulations |
we present karl g. jansky very large array observations of the co (2-1) line emission toward three far-infrared luminous quasars at z ∼ 6: sdss j231038.88+185519.7 and sdss j012958.51-003539.7 with ∼0.″6 resolution and sdss j205406.42-000514.8 with ∼2.″1 resolution. all three sources are detected in the co (2-1) line e... | star formation and ism properties in the host galaxies of three far-infrared luminous quasars at z ∼ 6 |
intermediate-mass black holes (imbhs) with masses between 100 {and} {10}5{m}⊙are crucial to our understanding of black hole seed formation and are the prime targets for the laser interferometer space antenna, yet black holes in this mass range have eluded detection by traditional optical spectroscopic surveys aimed at ... | the limitations of optical spectroscopic diagnostics in identifying active galactic nuclei in the low-mass regime |
the amount of cold, molecular gas in high-redshift galaxies is typically inferred from proxies of molecular hydrogen (h2), such as carbon monoxide (co) or neutral atomic carbon ([c i]) and molecular gas mass conversion factors. the use of these proxies, however, relies on modeling and observations that have not been di... | direct measurement of the [c i] luminosity to molecular gas mass conversion factor in high-redshift star-forming galaxies |
recent observations and simulations have challenged the long-held paradigm that mergers are the dominant mechanism driving the growth of both galaxies and supermassive black holes (smbh), in favour of non-merger (secular) processes. in this pilot study of merger-free smbh and galaxy growth, we use keck cosmic web image... | kiloparsec-scale agn outflows and feedback in merger-free galaxies |
changing-look active galactic nuclei (clagn) are agn that change type as their broad emission lines appear or disappear, which is usually accompanied by strong flux changes in their blue featureless continuum. we search for turn-on clagn by selecting type-2 agn from the spectroscopic six-degree field galaxy survey (6df... | skymapper colours of seyfert galaxies and changing-look agn - ii. newly discovered changing-look agn |
proximity zones of high-redshift quasars are unique probes of their central supermassive black holes as well as the intergalactic medium (igm) in the last stages of reionization. we present 22 new measurements of proximity zones of quasars with redshifts between 5.8 and 6.6, using the enlarged xqr-30 sample of high-res... | new quasar proximity zone size measurements at z 6 using the enlarged xqr-30 sample |
putting constraints on a possible lorentz invariance violation (liv) from astrophysical sources such as gamma-ray bursts (grbs) is essential for finding evidences of new theories of quantum gravity (qg) that predict an energy-dependent speed of light. this search has its own difficulties, so usually, the effect of the ... | impact of cosmology on lorentz invariance violation constraints from grb time-delays |
we determine here the peculiar motion of the solar system, first time from the m-z hubble diagram of quasars. observer's peculiar motion causes a systematic shift in the m-z plane between sources lying along the velocity vector and those in the opposite direction, providing a measure of the peculiar velocity. according... | solar system peculiar motion from the hubble diagram of quasars and testing the cosmological principle |
the novel gaia multi peak (gmp) technique has proven to be able to successfully select dual and lensed agn candidates at sub-arcsec separations. both populations are important because dual agns represent one of the central, still largely untested, predictions of lamdacdm cosmology, and compact lensed quasars allow to p... | muse ao spectroscopy confirms five dual agns and two strongly lensed qsos at sub-arcsec separation |
one of the most protracted problems in astronomy has been understanding the evolution of galaxy morphology. much discussion has surrounded how lenticular galaxies may form a bridging population between elliptical and spiral galaxies. however, with recourse to a galaxy's central black hole mass, accretion-built spiral g... | resequencing the hubble sequence and the quadratic (black hole mass)-(spheroid stellar mass) relation for elliptical galaxies |
large-scale magnetic fields in the nuclear regions of protogalaxies can promote the formation and early growth of supermassive black holes (smbhs) by direct collapse and magnetically boosted accretion. turbulence associated with gravitational infall and star formation can drive the rms field strength toward equipartiti... | magnetic fields catalyse massive black hole formation and growth |
modern hydrodynamical simulations reproduce many properties of the real universe. these simulations model various physical processes, but many of these are included using 'subgrid models' due to resolution limits. although different subgrid models have been successful in modelling the effects of supernovae (sne) and ac... | apostle-auriga: effects of different subgrid models on the baryon cycle around milky way-mass galaxies |
we present a comprehensive 5-43 ghz vlba study of the blazar 3c 273 initiated after an onset of a strong γ-ray flare in this source. we have analysed the kinematics of newborn components, light curves and position of the apparent core to pinpoint the location of the γ-ray emission. estimated location of the γ-ray emiss... | a connection between γ-ray and parsec-scale radio flares in the blazar 3c 273 |
the mechanisms that bring galaxies to strongly reduce their star formation activity (star-formation quenching) remain poorly understood. to better study galaxy evolution, we propose a classification based on maps of ionised hydrogen distribution traced by the kiloparsec-resolved, equivalent width of hα maps, and the nu... | star formation quenching stages of active and non-active galaxies |
galaxies and galaxy groups located along the line of sight towards gravitationally lensed quasars produce high-order perturbations of the gravitational potential at the lens position. when these perturbation are too large, they can induce a systematic error on h0 of a few per cent if the lens system is used for cosmolo... | h0licow - x. spectroscopic/imaging survey and galaxy-group identification around the strong gravitational lens system wfi 2033-4723 |
large-scale outflows are believed to be an important mechanism in the evolution of galaxies. we can determine the impact of these outflows by studying either current galaxy outflows and their effect in the galaxy or by studying the effect of past outflows on the gas surrounding the galaxy. in this work, we examine the ... | evidence of extended cold molecular gas and dust haloes around z 2.3 extremely red quasars with alma |
we investigate the abundance and distribution of metals in the high-redshift intergalactic medium and circum-galactic medium through the analysis of a sample of almost 600 si iv absorption lines detected in high- and intermediate-resolution spectra of 147 quasars. the evolution of the number density of si iv lines, the... | the evolution of the si iv content in the universe from the epoch of reionization to cosmic noon |
we reanalyze the mid-infrared (5-40 μm) spitzer spectra of 86 low-redshift (z < 0.5) palomar-green quasars to investigate the nature of polycyclic aromatic hydrocarbon (pah) emission and its utility as a star formation rate (sfr) indicator for the host galaxies of luminous active galactic nuclei (agns). we decompose... | the ionization and destruction of polycyclic aromatic hydrocarbons in powerful quasars |
we totally published 9,026,365 targets in this table, including 8,183,160 stars, 152,863 galaxies, 52,453 quasars, and 637,889 unknown objects. in addition, there are 5,808,985 objects with g band s/ns larger than 10, 7,701,235 objects with i band s/ns larger than 10, and 5,734,239 objects with g band s/ns larger than ... | vizier online data catalog: lamost dr5 catalogs (luo+, 2019) |
we conduct a comprehensive study of the effects of incorporating galaxy morphology information in photometric redshift estimation. using machine learning methods, we assess the changes in the scatter and outlier fraction of photometric redshifts when galaxy size, ellipticity, sérsic index, and surface brightness are in... | morpho-z: improving photometric redshifts with galaxy morphology |
we present a spectroscopically complete sample of 147 infrared-color-selected active galactic nuclei (agns) down to a 22 μm flux limit of 20 mjy over the ∼270 deg2 of the sloan digital sky survey stripe 82 region. most of these sources are in the qso luminosity regime (l bol ≳ 1012 l ⊙) and are found out to z ≃ 3. we c... | luminous wise-selected obscured, unobscured, and red quasars in stripe 82 |
we investigate the effects of extended multiyear light curves (9 yr photometry and 5 yr spectroscopy) on the detection of time lags between the continuum variability and broad-line response of quasars at z ≳ 1.5, and compare with the results using 4 yr photometry+spectroscopy presented in a companion paper. we demonstr... | the sloan digital sky survey reverberation mapping project: improving lag detection with an extended multiyear baseline |
the origin of supermassive black holes (smbhs) in galactic nuclei is one of the major unsolved problems in astrophysics. one hypothesis is that they grew from ≳ 105 m⊙ black holes that formed in the `direct collapse' of massive gas clouds that have low concentrations of both metals and molecular hydrogen (h2). such clo... | the suppression of direct collapse black hole formation by soft x-ray irradiation |
we report a candidate centi-parsec supermassive black hole binary (smbhb) in the radio-quiet quasar sdss j0159+0105 at z = 0.217. with a modified lomb-scargle code (glsdedrw) and auto-correlation analysis, we detect two significant (at p > 99%) periodic signals at ∼741 day and ∼1500 day from the 8.1 yr catalina v-ba... | sdss j0159+0105: a radio-quiet quasar with a centi-parsec supermassive black hole binary candidate |
we present a catalog of quasars with their corresponding redshifts derived from the photometric kilo-degree survey (kids) data release 4. we achieved it by training machine learning (ml) models, using optical ugri and near-infrared zyjhks bands, on objects known from sloan digital sky survey (sdss) spectroscopy. we def... | photometric selection and redshifts for quasars in the kilo-degree survey data release 4 |
narrow-line seyfert 1 galaxies (nls1s) are an interesting subclass of active galactic nuclei (agn), which tipically does not exhibit any strong radio emission. seven percent of them, though, are radio-loud and often show a flat radio-spectrum (f-nls1s). this, along to the detection of γ-ray emission coming from them, i... | compact steep-spectrum sources as the parent population of flat-spectrum radio-loud narrow-line seyfert 1 galaxies |
we use the high-resolution simulation massiveblackii to examine scaling relations between black hole (bh) mass and host galaxy properties (σ, total m* and lv), finding good agreement with recent observational data, especially at the high-mass end. we find gaussian intrinsic scatter (∼half the observed scatter) about al... | scaling relations between black holes and their host galaxies: comparing theoretical and observational measurements, and the impact of selection effects |
accretion is thought to primarily contribute to the mass accumulation history of supermassive black holes (smbhs) throughout cosmic time. while this may be true at high redshifts, at lower redshifts and for the most massive black holes (bhs) mergers themselves might add significantly to the mass budget. we explore this... | understanding black hole mass assembly via accretion and mergers at late times in cosmological simulations |
we discuss 76 large amplitude transients (δm > 1.5) occurring in the nuclei of galaxies, nearly all with no previously known active galactic nucleus (agn). they have been discovered as part of the pan-starrs1 (ps1) 3π survey, by comparison with sloan digital sky survey (sdss) photometry a decade earlier, and then mo... | slow-blue nuclear hypervariables in panstarrs-1 |
we introduce an intrinsic lyα emission-line profile reconstruction method for high-z quasars (qsos). this approach utilises a covariance matrix of emission-line properties obtained from a large, moderate-z (2 ≤ z ≤ 2.5), high signal to noise (s/n > 15) sample of boss qsos. for each qso, we complete a monte carlo mar... | lyα emission-line reconstruction for high-z qsos |
supermassive binary black holes at subparsec orbital separations have yet to be discovered, with the possible exception of blazar oj 287. in parallel to the global hunt for nanohertz gravitational waves from supermassive binaries using pulsar timing arrays, there has been a growing sample of candidates reported from el... | toward the unambiguous identification of supermassive binary black holes through bayesian inference |
primordial supermassive stars (smss) formed in atomic-cooling halos at z ~ 15-20 are leading candidates for the seeds of the first quasars. past numerical studies of the evolution of smss have typically assumed constant accretion rates rather than the highly variable flows in which they form. we model the evolution of ... | on the evolution of supermassive primordial stars in cosmological flows |
massive black hole binaries (mbhbs) form as a consequence of galaxy mergers. however, it is still unclear whether they typically merge within a hubble time, and how accretion may affect their evolution. these questions will be addressed by pulsar timing arrays (ptas), which aim to detect the gravitational wave (gw) bac... | the effect of differential accretion on the gravitational wave background and the present-day mbh binary population |
in this paper we use a newly compiled sample of ultra-compact structure in radio quasars and strong gravitational lensing systems with quasars acting as background sources to constrain six spatially flat and non-flat cosmological models (λcdm, pede, and dgp). these two sets of quasar data (time-delay measurements of si... | revising the hubble constant, spatial curvature and dark energy dynamics with the latest observations of quasars |
we present atacama large millimeter/submillimeter array (alma) sub-kiloparsec- to kiloparsec-scale resolution observations of the [c ii], co (9-8), and oh+ (11-01) lines along with their dust continuum emission toward the far-infrared (fir) luminous quasar sdss j231038.88+185519.7 at z = 6.0031, to study the interstell... | the interstellar medium distribution, gas kinematics, and system dynamics of the far-infrared luminous quasar sdss j2310+1855 at z = 6.0 |
blazars are a peculiar class of active galactic nuclei that enlighten the sky at all wavelengths. the electromagnetic emission of these sources is jet-dominated, resulting in a spectral energy distribution (sed) that has a typical double-humped shape. x-ray photons provide a wealth of information on the physics of each... | the first hard x-ray spectral catalogue of blazars observed by nustar |
we study the demographics of z ~ 6 broad-line quasars in the black hole (bh) mass-luminosity plane using a sample of more than 100 quasars at 5.7 < z < 6.5. these quasars have well-quantified selection functions and nearly one-third of them also have virial bh masses estimated from near-ir spectroscopy. we use fo... | demographics of z 6 quasars in the black hole mass-luminosity plane |
high resolution spectra of quasar absorption systems provide the best constraints on temporal or spatial changes of fundamental constants in the early universe. an important systematic that has never before been quantified concerns model non-uniqueness. the absorption structure is generally complicated, comprising many... | non-uniqueness in quasar absorption models and implications for measurements of the fine structure constant |
we present a model for spectrophotometric calibration errors in observations of quasars from the third generation of the sloan digital sky survey baryon oscillation spectroscopic survey (boss) and describe the correction procedure we have developed and applied to this sample. calibration errors are primarily due to atm... | improved spectrophotometric calibration of the sdss-iii boss quasar sample |
although the speed of light has been measured with very high precision, most of these measurements were carried out on earth or in our close cosmic surroundings. in this letter, we propose an original idea to combine the observations of ultra-compact structure in radio quasars and strong gravitational lensing with quas... | precise measurements of the speed of light with high-redshift quasars: ultra-compact radio structure and strong gravitational lensing |
we present muse observations of the field of the quasar q0152$-$020 whose spectrum shows a lyman limit system (lls) at redshift $z_{\rm abs} = 0.38$, with a metallicity z $\gtrsim 0.06$ z$_\odot$. the low ionization metal lines associated with the lls present two narrow distinct absorption components with a velocity se... | observational signatures of a warped disk associated with cold-flow accretion |
we present a detailed analysis of a recent, 2013 suzaku campaign on the nearby (z = 0.184) luminous (lbol ∼ 1047 erg s-1) quasar pds 456. this consisted of three observations, covering a total duration of ∼1 ms and a net exposure of 455 ks. during these observations, the x-ray flux was unusually low, suppressed by a fa... | short-term x-ray spectral variability of the quasar pds 456 observed in a low-flux state |
red quasi-stellar objects (qsos) are a subset of the luminous end of the cosmic population of active galactic nuclei (agns), most of which are reddened by intervening dust along the line of sight towards their central engines. in recent work from our team, we developed a systematic technique to select red qsos from the... | fundamental differences in the radio properties of red and blue quasars: insight from the lofar two-metre sky survey (lotss) |
we present a detailed study of ionized outflows in a large sample of ∼650 hard x-ray-detected active galactic neuclei (agns). using optical spectroscopy from the bat agn spectroscopic survey (bass), we are able to reveal the faint wings of the [o iii] emission lines associated with outflows covering, for the first time... | bat agn spectroscopic survey - xix. type 1 versus type 2 agn dichotomy from the point of view of ionized outflows |
blazars, one of the most extreme classes of active galaxies, constitute so far the largest known population of γ-ray sources, and their number is continuously growing in the fermi catalogs. however, in the latest release of the fermi catalog there is still a large fraction of sources that are classified as blazar candi... | optical spectroscopic observations of gamma-ray blazar candidates. vi. further observations from tng, wht, oan, soar, and magellan telescopes |
in this paper, we report on the observational performance of the swift ultra-violet/optical telescope (uvot) in response to the gravitational wave (gw) alerts announced by the advanced laser interferometer gravitational wave observatory and the advanced virgo detector during the o3 period. we provide the observational ... | swift/uvot follow-up of gravitational wave alerts in the o3 era |
we present the discovery of eight quasars at z∼ 6 identified in the sloan digital sky survey (sdss) overlap regions. individual sdss imaging runs have some overlap with each other, leading to repeat observations over an area spanning >4000 deg2 (more than one-fourth of the total footprint). these overlap regions pro... | discovery of eight z ∼ 6 quasars in the sloan digital sky survey overlap regions |
we review results from our monitoring observations of several lensed quasars performed in the optical, uv, and x-ray bands. modeling of the multi-wavelength light curves provides constraints on the extent of the optical, uv, and x-ray emission regions. one of the important results of our analysis is that the optical si... | gravitational lensing size scales for quasars |
we report the discovery of rapid variations of a high-velocity c iv broad absorption line trough in the quasar sdss j141007.74+541203.3. this object was intensively observed in 2014 as a part of the sloan digital sky survey reverberation mapping project, during which 32 epochs of spectroscopy were obtained with the bar... | the sloan digital sky survey reverberation mapping project: rapid civ broad absorption line variability |
the formation of supermassive stars is believed to be an essential intermediate step for the formation of the massive black hole seeds that become the supermassive black holes powering the quasars observed in the early universe. numerical simulations have shown that supermassive stars can form in atomic-cooling haloes ... | formation of supermassive stars in the first star clusters |
we propose a new method for fitting the full-shape of the lyman-α (ly α) forest 3d correlation function in order to measure the alcock-paczynski (ap) effect. our method preserves the robustness of baryon acoustic oscillations (bao) analyses, while also providing extra cosmological information from a broader range of sc... | cosmology beyond bao from the 3d distribution of the lyman-α forest |
we present alma band 9 continuum observation of the ultraluminous quasi-stellar object (qso) sdss j0100+2802 providing a ~10σ detection at ~670 ghz. sdss j0100+2802 is the brightest qso with the most massive supermassive black hole (smbh) known at z > 6, and we study its dust spectral energy distribution in order to... | accurate dust temperature and star formation rate in the most luminous z > 6 quasar in the hyperluminous quasars at the epoch of reionization (hyperion) sample |
dusty quasars might be in a young stage of galaxy evolution with prominent quasar feedback. a recently discovered population of luminous, extremely red quasars at z ~ 2-4 has extreme spectral properties related to exceptionally powerful quasar-driven outflows. we present keck/kcwi observations of the reddest known erq,... | probing the inner circumgalactic medium and quasar illumination around the reddest 'extremely red quasar' |
intervening c iv absorbers are key tracers of metal-enriched gas in galaxy haloes over cosmic time. previous studies suggest that the c iv cosmic mass density ($\omega _{\rm c \, \small {iv}}$) decreases slowly over 1.5 $\lesssim \, z\lesssim$ 5 before declining rapidly at z ≳ 5, but the cause of this downturn is poorl... | examining the decline in the c iv content of the universe over 4.3 ≲ z ≲ 6.3 using the e-xqr-30 sample |
as the universe evolves, it develops a web of filamentary structure of matter. this cosmic web is filled with gas, with the most diffuse gas lying in the intergalactic regions. at low redshift, the gas is predominantly warm-hot, and one of its best tracers is x-ray absorption in sightlines to background quasars. in thi... | absorption studies of the most diffuse gas in the large scale structure |
the largest fluctuation in the cmb sky is the cmb dipole, which is believed to be caused by the motion of our observation frame with respect to the cmb rest frame. this motion accounts for the known motion of the solar system barycentre with a best-fit amplitude of 369 km/s, in the direction (ℓ= 264°, b=48°) in galacti... | bayesian estimation of our local motion from the planck-2018 cmb temperature map |
we report the constraints of h0 obtained from wilkinson microwave anisotropy probe (wmap) 9-year data combined with the latest baryonic acoustic oscillations (bao) measurements. we use the bao measurements from 6df galaxy survey (6dfgs), the sdss dr7 main galaxies sample (mgs), the boss dr12 galaxies, and the eboss dr1... | constraints on h 0 from wmap and bao measurements |
we present the novel algorithmically regularized integration method mstar for high-accuracy (|δe/e| ≳ 10-14) integrations of n-body systems using minimum spanning tree coordinates. the twofold parallelization of the o(n_part^2) force loops and the substep divisions of the extrapolation method allow for a parallel scali... | mstar - a fast parallelized algorithmically regularized integrator with minimum spanning tree coordinates |
after the discovery of powerful relativistic jets from narrow-line seyfert 1 galaxies, and the understanding of their similarity with those of blazars, a problem of terminology was born. the word blazar is today associated to bl lac objects and flat-spectrum radio quasars, which are somehow different from narrow-line s... | what we talk about when we talk about blazars? |
we present alma observations of cold dust and molecular gas in four high-luminosity, heavily reddened (av ∼ 2.5-6 mag) type 1 quasars at z ∼ 2.5 with virial mbh ∼ 1010 m⊙, to test whether dusty, massive quasars represent the evolutionary link between submillimetre-bright galaxies and unobscured quasars. all four quasar... | the discovery of gas-rich, dusty starbursts in luminous reddened quasars at z ∼ 2.5 with alma |
while molecular quasar absorption systems provide unique probes of the physical and chemical properties of the gas as well as original constraints on fundamental physics and cosmology, their detection remains challenging. here we present the results from a complete survey for molecular gas in thirty-nine absorption sys... | spotting high-z molecular absorbers using neutral carbon. results from a complete spectroscopic survey with the vlt |
using an ultra-deep blind survey with the muse integral field spectrograph on the european southern observatory very large telescope, we obtain spectroscopic redshifts to a depth never before explored: galaxies with observed magnitudes m ab ≳ 30-32. specifically, we detect objects via lyα emission at 2.9 < z < 6.... | muse spectroscopic identifications of ultra-faint emission line galaxies with m uv ∼ -15 |
we develop a semi-analytic model to explore different prescriptions of supermassive black hole (smbh) fuelling. this model utilizes a merger-triggered burst mode in concert with two possible implementations of a long-lived steady mode for assembling the mass of the black hole in a galactic nucleus. we improve modelling... | exploring smbh assembly with semi-analytic modelling |
recent theoretical models suggest that the early phase of galaxy formation could involve an epoch when galaxies are gas rich but inefficient at forming stars: a “dark galaxy” phase. here, we report the results of our multi-unit spectroscopic explorer (muse) survey for dark galaxies fluorescently illuminated by quasars ... | dark galaxy candidates at redshift ∼3.5 detected with muse |
we propose to solve the dark energy problem by postulating the massless sector of closed strings. this sector constitutes the gravitational multiplet of string theory and, when applied to four-dimensional cosmology, predicts that the expansion of an open universe defined in string frame is readily accelerating. we conf... | late-time cosmology without dark sector but with closed string massless sector |
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