Bringing faint active galactic nuclei (AGNs) to light: a view from large-scale cosmological simulations
Adrian P. Schirra, Melanie Habouzit, Ralf S. Klessen, Francesca Fornasini, Dylan Nelson, Annalisa Pillepich, Daniel Anglés-Alcázar, Romeel Davé, Francesca Civano
备注：
Published version - MNRAS
发表信息：
MNRAS, Volume 508, Issue 4, December 2021, Pages 4816-4843
The sensitivity of X-ray facilities and our ability to detect fainter active galactic nuclei (AGNs) will increase with the upcoming Athena mission and the AXIS and Lynx concept missions, thus improving our understanding of supermassive black holes (BHs) in a luminosity regime that can be dominated by X-ray binaries. We analyze the population of faint AGN (L_x (2-10 keV) < 10^42 erg/s) in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations, and find that the properties of their host galaxies vary from one simulation to another. In Illustris and EAGLE, faint AGN are powered by low-mass BHs located in low-mass star-forming galaxies. In TNG100 and SIMBA, they are mostly associated with more massive BHs in quenched massive galaxies. We model the X-ray binary populations (XRB) of the simulated galaxies, and find that AGN often dominate the galaxy AGN+XRB hard X-ray luminosity at z>2, while XRBs dominate in some simulations at z<2. Whether the AGN or XRB emission dominates in star-forming and quenched galaxies depends on the simulations. These differences in simulations can be used to discriminate between galaxy formation models with future high-resolution X-ray observations. We compare the luminosity of simulated faint AGN host galaxies to observations of stacked galaxies from Chandra. Our comparison indicates that the simulations post-processed with our X-ray modeling tend to overestimate the AGN+XRB X-ray luminosity; luminosity that can be strongly affected by AGN obscuration. Some simulations reveal clear AGN trends as a function of stellar mass (e.g., galaxy luminosity drop in massive galaxies), which are not apparent in the observations.
Finding the sources responsible for the hydrogen reionization is one of the most pressing issues in cosmology. Bright QSOs are known to ionize their surrounding neighborhood, but they are too few to ensure the required HI ionizing background. A significant contribution by faint AGNs, however, could solve the problem, as recently advocated on the basis of a relatively large space density of faint active nuclei at z>4. We have carried out an exploratory spectroscopic program to measure the HI ionizing emission of 16 faint AGNs spanning a broad U-I color interval, with I~21-23 and 3.6<z<4.2. Thes…
Infrared-Faint Radio Sources (IFRS) represent an unexpected class of objects relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S_{1.4GHz} >= 10 mJy) has provided evidence that most of them (if not all) contain an AGN. Still uncertain is the nature of the radio-faintest ones (S_{1.4GHz} <= 1 mJy). The scope of this paper is to assess the nature of the radio-faintest IFRSs, testing their classification and improving the knowledge of their IR properties making use of the most sensitive…
It is now established that the faint radio population is a mixture of star-forming galaxies and faint active galactic nuclei (AGNs), with the former dominating below S(1.4GHz) \sim 100 muJy and the latter at larger flux densities. The faint radio AGN component can itself be separated into two main classes, mainly based on the host-galaxy properties: sources associated with red/early-type galaxies (like radio galaxies) are the dominant class down to \sim 100 muJy; quasar/Seyfert--like sources contribute an additional 10-20\%. One of the major open questions regarding faint radio AGNs is the phy…
We present new Keck/MOSFIRE K-band spectroscopy for a sample of 14 faint, X-ray-selected active galactic nuclei (AGNs) in the COSMOS field. The data cover the spectral region surrounding the broad Balmer emission lines, which enables the estimation of black hole masses (M_BH) and accretion rates (in terms of L/L_Edd). We focus on 10 AGN at z~3.3, where we observe the Hbeta spectral region, while for the other four z~2.4 sources we use the Halpha broad emission line. Compared with previous detailed studies of unobscured AGNs at these high redshifts, our sources are fainter by an order of magnit…
Infrared-faint radio sources (IFRS) form a new class of galaxies characterised by radio flux densities between tenths and tens of mJy and faint or absent infrared counterparts. It has been suggested that these objects are radio-loud active galactic nuclei (AGNs) at significant redshifts (z >~ 2). Whereas the high redshifts of IFRS have been recently confirmed based on spectroscopic data, the evidence for the presence of AGNs in IFRS is mainly indirect. So far, only two AGNs have been unquestionably confirmed in IFRS based on very long baseline interferometry (VLBI) observations. In this work, …
Identifying the source population of ionizing radiation, responsible for the reionization of the universe, is currently a hotly debated subject with conflicting results. Studies of faint, high-redshift star-forming galaxies, in most cases, fail to detect enough escaping ionizing radiation to sustain the process. Recently, the capacity of bright quasi-stellar objects to ionize their surrounding medium has been confirmed also for faint active galactic nuclei (AGNs), which were found to display an escaping fraction of ~74% at z~4. Such levels of escaping radiation could sustain the required UV ba…
Inconsistent conclusions are obtained from recent active galactic nuclei (AGNs) accretion disk inter-band time-lag measurements. While some works show that the measured time lags are significantly larger (by a factor of $\sim 3$) than the theoretical predictions of the Shakura \& Sunyaev disk (SSD) model, others find that the time-lag measurements are consistent with (or only slightly larger than) that of the SSD model. These conflicting observational results might be symptoms of our poor understanding of AGN accretion physics. Here we show that sources with larger-than-expected time lags tend…
Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combinat…
In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at $z>4$ in the CANDELS GOODS-South field which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer and various groundbased telescopes. We have adopted a relatively novel criterion. As a first step high redshift galaxies are selected in the NIR $H$ band down to very faint levels ($H\leq27$) using reliable photometric redshifts. This corresponds at $z>4$ to a selection criterion based on the galaxy rest-frame UV flux. AGN candidates ar…
Identifying Active Galactic Nuclei (AGNs) through their X-ray emission is efficient, but necessarily biased against X-ray-faint objects. We aim to characterize this bias by comparing X-ray-selected AGNs to the ones identified through optical variability and mid-IR colours. We present a catalogue of AGNs selected through optical variability using all publicly available z-band Hubble Space Telescope images in the GOODS-South field. For all objects in the catalogue, we compute X-ray upper limits or discuss detections in the deepest available 7 Ms Chandra Deep Field South images and present the Sp…
Building a large sample of kiloparsec (kpc)-scale dual active galactic nuclei (AGNs) amongst merging galaxies is of vital importance to understand the co-evolution between host galaxies and their central super massive black holes (SMBHs). Doing so, with just such a sample, we have developed an innovative method of systematically searching and identifying dual AGNs of amongst kpc scale merging galaxies and selected 222 candidates at redshifts $\leqslant$ 0.25. All the selected candidates have FIRST radio detection and at least one of two cores previously revealed as AGN spectroscopically. We re…
We investigate the Eddington ratio distribution of X-ray selected broad-line active galactic nuclei (AGN) in the redshift range 1.0<z<2.2, where the number density of AGNs peaks. Combining the optical and Subaru/FMOS near-infrared spectroscopy, we estimate black hole masses for broad-line AGNs in the Chandra Deep Field-South (CDF-S), Extended Chandra Deep Field-South (E-CDF-S), and the XMM-Newton Lockman Hole (XMM-LH) surveys. AGNs with similar black hole masses show a broad range of AGN bolometric luminosities, which are calculated from X-ray luminosities, indicating that the accretion rate o…
We present results of single-epoch very long baseline interferometry (VLBI) observations of gamma-ray bright active galactic nuclei (AGNs) using the Korean VLBI Network (KVN) at 22, 43, 86, and 129~GHz bands, which are part of a KVN key science program, Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA). We selected a total of 34 radio-loud AGNs of which 30 sources are gamma-ray bright AGNs with flux densities of $>6\times10^{-10}$~ph~cm$^{-2}$~s$^{-1}$. Single-epoch multi-frequency VLBI observations of the target sources were conducted during a 24-hr session on 2013 November 19 and…
We present a sample of 10 low-mass active galactic nuclei (AGNs) selected from the 40-month NuSTAR serendipitous survey. The sample is selected to have robust NuSTAR detections at $3 - 24$~keV, to be at $z < 0.3$, and to have optical r-band magnitudes at least 0.5~mag fainter than an $L_\star$ galaxy at its redshift. The median values of absolute magnitude, stellar mass and 2--10 X-ray luminosity of our sample are $\langle M_r\rangle = -20.03$, $\langle M_\star\rangle = 4.6\times10^{9}M_\odot$, and $\langle L_{2-10\mathrm{keV}}\rangle = 3.1\times10^{42}$ erg s$^{-1}$, respectively. Five object…
We report the result of optical identifications of FIRST radio sources with the Hyper Suprime-Cam Subaru Strategic Program survey (HSC-SSP). The positional cross-match within 1" between the FIRST and HSC-SSP catalogs (i ~< 26) produced more than 3600 optical counterparts in the 156 deg^2 of the HSC-SSP field. The matched counterparts account for more than 50% of the FIRST sources in the search field, which substantially exceed previously reported fractions of SDSS counterparts (i ~< 22) of ~30%. Among the matched sample, 9% are optically unresolved sources such as radio-loud quasars. The optic…
We present new measurements of the evolution of the X-ray luminosity functions (XLFs) of unabsorbed and absorbed Active Galactic Nuclei (AGNs) out to z~5. We construct samples containing 2957 sources detected at hard (2-7 keV) X-ray energies and 4351 sources detected at soft (0.5-2 keV) energies from a compilation of Chandra surveys supplemented by wide-area surveys from ASCA} and ROSAT. We consider the hard and soft X-ray samples separately and find that the XLF based on either (initially neglecting absorption effects) is best described by a new flexible model parametrization where the break …
The study of the space density of bright AGNs at $z>4$ has been subject to extensive effort given its importance for the estimate of the cosmological ionizing emissivity and growth of supermassive black holes. In this context we have recently derived high space densities of AGNs at $z\sim 4$ and $-25<M_{1450}<-23$ in the COSMOS field from a spectroscopically complete sample. In the present paper we attempt to extend the knowledge of the AGN space density at fainter magnitudes ($-22.5<M_{1450}<-18.5$) in the $4<z<6.1$ redshift interval by means of a multiwavelength sample of galaxies in the CAN…
In this paper, we utilize high-quality rest-UV spectra of three radio galaxies at $z \sim$ 3 observed with VLT/FORS2 to measure the flux of several emission lines including relatively faint ones, such as NIV]$λ$1486, OIII]$λ$1663, and [NeIV]$λ$2424. Additionally, we collect fluxes of faint rest-UV emission lines in 12 $z \sim$ 3 radio galaxies from the literature. Previously, physical and chemical properties of narrow-line regions (NLRs) in high-$z$ active galactic nuclei (AGNs) have been investigated mostly by using only strong rest-UV emission-lines (e.g., NV$λ$1240, CIV$λ$1549, HeII$λ$1640,…
We present an analysis of the nuclear variability of $\sim28,000$ nearby ($z<0.15$) galaxies with Sloan Digital Sky Survey (SDSS) spectroscopy in Stripe 82. We construct light curves using difference imaging of SDSS g-band images, which allows us to detect subtle variations in the central light output. We select variable AGN by assessing whether detected variability is well-described by a damped random walk model. We find 135 galaxies with AGN-like nuclear variability. While most of the variability-selected AGNs have narrow emission lines consistent with the presence of an AGN, a small fractio…
The spatial clustering of active galactic nuclei (AGNs) is considered to be one of the important diagnostics for the understanding of the underlying processes behind their activities complementary to measurements of the luminosity function (LF). We analyse the AGN clustering from a recent semi-analytic model performed on a large cosmological $N$-body simulation covering a cubic gigaparsec comoving volume. We have introduced a new time-scale of gas accretion on to the supermassive black holes to account for the loss of the angular momentum on small scales, which is required to match the faint e…
We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES) and data in the radio (WSRT 1.4 GHz), X-rays (Chandra XBootes), and mid-IR (IRAC Shallow Survey). The radio, X-ray, and IR AGN samples show modest overlap, indicating that to the flux limits of the survey, they represent largely distinct cl…
We present a joint analysis of the rest-frame ultraviolet (UV) luminosity functions of continuum-selected star-forming galaxies and galaxies dominated by active galactic nuclei (AGNs) at $z \sim$ 4. These 3,740 $z \sim$ 4 galaxies are selected from broad-band imaging in nine photometric bands over 18 deg$^2$ in the \textit{Spitzer}/HETDEX Exploratory Large Area Survey (SHELA) field. The large area and moderate depth of our survey provide a unique view of the intersection between the bright end of the galaxy UV luminosity function (M$_{AB}<-$22) and the faint end of the AGN UV luminosity functi…
We present arcsecond-scale observations of the active galactic nuclei (AGNs) of seven nearby Seyfert galaxies observed from the Stratospheric Observatory For Infrared Astronomy (SOFIA) using the 31.5 and 37.1 um filters of the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We isolate unresolved emission from the torus and find extended diffuse emission in six 37.1 um residual images in our sample. Using Spitzer/IRS spectra, we determine the dominant mid-infrared (MIR) extended emission source and attribute it to dust in the narrow line region (NLR) or star formation. We compar…
We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have two optical AGN emission components separated by >0.2", and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without follow-up observations, the sources of the double-peaked narrow emission lines are uncertain, and may be produced by kpc-scale separation dual active supermassive black holes, AGN outflows, or disk rotation. In this work, we propose a new methodology to…
Studies of the high-redshift rest-frame ultraviolet (UV) luminosity functions (LFs) have typically treated the star-forming galaxy and active galactic nuclei (AGN) populations separately, as they have different survey depth and area requirements. However, the recent advent of wide-area deep ground-based imaging surveys now probe volumes large enough to discover AGNs, at depths sensitive enough for fainter star-forming galaxies, bridging these two populations. Using results from such surveys as observational constraints, we present a methodology to jointly empirically model the evolution of the…
We present infrared K'- (2.1 micron) and L'-band (3.8 micron) high-spatial-resolution (<0.3") imaging observations of 17 nearby (z < 0.17) ultraluminous infrared galaxies (ULIRGs) assisted with the adaptive optics of the Subaru Telescope. We search for compact red K'-L' color emission as the indicator of luminous active galactic nuclei (AGNs) due to AGN-heated hot dust emission. Two luminous dual AGN candidates are revealed. Combining these results with those of our previous study, we can state that the detected fraction of luminous dual AGNs in nearby ULIRGs is much less than unity (<20%), ev…
We present a flux-limited sample of $z\sim0.3$ Ly$α$ emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism spectroscopic data. The published GALEX $z\sim0.3$ LAE sample is pre-selected from continuum-bright objects and thus is biased against high equivalent width (EW) LAEs. We remove this continuum pre-selection and compute the EW distribution and the luminosity function of the Ly$α$ emission line directly from our sample. We examine the evolution of these quantities from $z\sim0.3$ to $2.2$ and find that the EW distribution shows little evidence for evolution over this redshift range. …
We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared (IR) wavebands from the wide-field (9 deg^2) Bootes survey. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES). We find that radio and X-ray AGNs reside in relatively large dark matter halos (M_halo ~ 3x10^13 and 10^13 h^-1 M_sun, respectively) and are found in galaxies with red and "green" …
We study the redshift evolution of the quasar UV Luminosity Function (LF) for 0.5 < z < 6.5, by collecting the most up to date observational data and, in particular, the recently discovered population of faint AGNs. We fit the QSO LF using either a double power-law or a Schechter function, finding that both forms provide good fits to the data. We derive empirical relations for the LF parameters as a function of redshift and, based on these results, predict the quasar UV LF at z=8. From the inferred LF evolution, we compute the redshift evolution of the QSO/AGN comoving ionizing emissivity and …
JWST Spectroscopic Census of ALMA Faint Submillimeter Galaxies in the Hubble Ultra Deep Field
The Graduate University for Advanced Studies, SOKENDAI（日本高级研究院）；National Astronomical Observatory of Japan（日本国立天文台）；Institute for Cosmic Ray Research, The University of Tokyo（东京大学宇宙射线研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo（东京大学 Kavli 宇宙物理数学研究所）；David A. Dunlap Department of Astronomy and Astrophysics, University of Toronto（多伦多大学大卫·邓普天文学与天体物理学系）；Dunlap Institute for Astronomy and Astrophysics（邓普天文学与天体物理学研究所）
HI 21-cm absorption in low- and high-excitation radio-loud AGNs at $z<0.5$ from MALS
Inter-University Centre for Astronomy and Astrophysics（大学间天体物理中心）；University of Cape Town（开普敦大学）；SARAO（南非射电天文台）；Université Lyon1（里昂第一大学）；ENS de Lyon（里昂高等师范学校）；CNRS（法国国家科学研究中心）；Centre de Recherche Astrophysique de Lyon（里昂天体物理研究中心）；French-Chilean Laboratory for Astronomy（法智利天文联合实验室）；Universidad de Chile（智利大学）；Ioffe Institute（约费研究所）；Department of Astronomy and Astrophysics, The University of Chicago（芝加哥大学天文与天体物理系）；Observatoire de Paris（巴黎天文台）；Collège de France（法兰西公学院）；PSL University（巴黎文理研究大学）；Sorbonne University（索邦大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Institut d’Astrophysique de Paris（巴黎天体物理研究所）
Back to basics: Little Red Dots as galaxies and dust-obscured AGNs in a synthetic NIRCam sky simulated with L-GalaxiesBH
Donostia International Physics Centre (DIPC)（多诺斯蒂亚国际物理中心）；University of the Basque Country UPV/EHU（巴斯克国立大学）；Como Lake Center for AstroPhysics, University of Insubria（因斯布鲁克大学科莫湖天体物理中心）；Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca（米兰比可卡大学 G. Occhialini 物理系）；INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰比可卡分部）；Key Laboratory for Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台计算天体物理学重点实验室）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天文与天体物理研究所）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（加泰罗尼亚高等研究学院，西班牙国家科研委员会））
We present a study of spectral properties of galaxies in underdense large-scale structures, voids. Our void galaxy sample (75,939 galaxies) is selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) with $\rm z < 0.107$. We find that there are no significant differences in the luminosities, stellar masses, stellar populations, and specific star formation rates between void galaxies of specific spectral types and their wall counterparts. However, the fraction of star-forming galaxies in voids is significantly higher ($\ge 9\%$) than that in walls. Void galaxies, when considering …
The rapidly declining population of bright quasars at z~3 appears to make an increasingly small contribution to the ionising background at the HI Lyman limit. It is then generally though that massive stars in (pre-)galactic systems may provide the additional ionising flux needed to complete HI reionisation by z>6. A galaxy dominated background, however, may require that the escape fraction of Lyman continuum radiation from high redshift galaxies is as high as 10%, a value somewhat at odds with (admittedly scarce) observational constraints. High escape fractions from dwarf galaxies have been ad…
We construct a sample of X-ray bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared source catalogs. 53 X-ray sources satisfying i band magnitude fainter than 23.5 mag and X-ray counts with EPIC-PN detector larger than 70 are selected from 9.1 deg^2, and their spectral energy distributions (SEDs) and X-ray spectra are analyzed. 44 objects with an X-ray to i-band flux ratio F_X/F_i>10 are classified as extreme X-ray-to-optical flux sources. SEDs of 48 among 53 are represented by templates of type 2 AGNs or starforming galaxies and show si…
Galaxy-scale outflows are nowadays observed in many active galactic nuclei (AGNs); however, their characterisation in terms of (multi-) phase nature, amount of flowing material, effects on the host galaxy, is still unsettled. In particular, ionized gas mass outflow rate and related energetics are still affected by many sources of uncertainties. In this respect, outflowing gas plasma conditions, being largely unknown, play a crucial role. Taking advantage of the spectroscopic analysis results we obtained studying the X-ray/SDSS sample of 563 AGNs at z $<0.8$ presented in our companion paper, we…
We present the Lya luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3,137 Lya emitters (LAEs) at $z = 2.2$ in five independent blank fields. The sample of these LAEs is the largest, to date, and covers a very wide Lya luminosity range of $\log L_{Lyα} = 41.7-44.4$ erg s$^{-1}$. We determine the Lya LF at $z = 2.2$ with unprecedented accuracies, and obtain the best-fit Schechter parameters of $L^{*}_{Lyα} = 5.29^{+1.67}_{-1.13} \times 10^{42}$ erg s$^{-1}$, $ϕ^{*}_{Lyα} = 6.32^{+3.08}_{-2.31} \times 10^{-4}$ Mpc$^{-3}$, and $α= -1.75^{+0.10}_{-0…
We present the luminosity function of z=4 quasars based on the Hyper Suprime-Cam Subaru Strategic Program Wide layer imaging data in the g, r, i, z, and y bands covering 339.8 deg^2. From stellar objects, 1666 z~4 quasar candidates are selected by the g-dropout selection down to i=24.0 mag. Their photometric redshifts cover the redshift range between 3.6 and 4.3 with an average of 3.9. In combination with the quasar sample from the Sloan Digital Sky Survey in the same redshift range, the quasar luminosity function covering the wide luminosity range of M1450=-22 to -29 mag is constructed. It is…
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 rates (SFRs) via a multi-component SED fitting technique. Type 1 and Type 2 AGNs follow the same intrinsic Lx-L6um relation, suggesting that mid-infrared emission is a reasonably good measure of the AGN accretion power regardless of obscuration. We find that there is a strong increas…
Cold Dark Matter (CDM) models struggle to match the observations at galactic scales. The tension can be reduced either by dramatic baryonic feedback effects or by modifying the particle physics of CDM. Here, we consider an ultra-light scalar field DM particle manifesting a wave nature below a DM particle mass-dependent Jeans scale. For DM mass $m\sim10^{-22}{\rm eV}$, this scenario delays galaxy formation and avoids cusps in the center of the dark matter haloes. We use new measurements of half-light mass in ultra-faint dwarf galaxies Draco II and Triangulum II to estimate the mass of the DM pa…
Understanding the detailed process of cosmic reionization is one of the remaining problems in astrophysics and cosmology. Here we construct a model of cosmic reionization that includes contribution from high-$z$ galaxies and active galactic nuclei (AGNs), and calculate the reionization and thermal histories with the model. To keep the model to be general and realistic, we vary the escape fraction of ionizing photons, $f_{\rm esc}$, and the faint-end slope of the AGN luminosity function at high redshifts, $α_{\rm hz}$, within the constraints from the observed cosmic star formation history and t…
Context: Variations in the mass accretion rate appear to be responsible for the rapid transitions in spectral type that are observed in increasingly more active galactic nuclei (AGNs). These objects are now labeled "changing-look" AGNs and are key objects for understanding the physics of accretion onto supermassive black holes. Aims: We aim to complement the analysis and interpretation of changing-look AGNs by modeling the polarization variations that can be observed, in particular, polarized-light echoes. Methods: We built a complex and representative model of an AGN and its host galaxy and r…
Large-scale outflows are generally considered as a possible evidence that active galactic nuclei (AGNs) can severely affect their host galaxies. Recently an ultraluminous IR galaxy (ULIRG) at $z=0.49$, AKARI J0916248+073034, was found to have a galaxy-scale [OIII] $λ$5007 outflow with one of the highest energy-ejection rates at $z<1.6$. However, the central AGN activity estimated from its torus mid-IR (MIR) radiation is weak relative to the luminous [OIII] emission. In this work we report the first NuSTAR hard X-ray follow-up of this ULIRG to constrain its current AGN luminosity. The intrinsic…
GMP-selected dual and lensed AGNs: selection function and classification based on near-IR colors and resolved spectra from VLT/ERIS, KECK/OSIRIS, and LBT/LUCI
