We present a new relationship between central black hole (BH) mass and host galaxy stellar bulge mass extending to the lowest BH masses known in dwarf galaxies ($M_{\rm BH} \lesssim 10^{5} M_{\odot}$; $M_{\star} \sim 10^{9} M_{\odot}$). We have obtained visible and near-infrared $Hubble \ Space \ Telescope \ (HST)$ imaging of seven dwarf galaxies with optically-selected broad-line active galactic nuclei (AGN) and BH mass estimates from single epoch spectroscopy. We perform 2D photometric modeling with GALFIT to decompose the structure of these galaxies and find that the majority have an inner bulge/pseudobulge component with an exponential disk that dominates the total stellar mass. Using the modeling results and color-dependent mass-to-light ratios, we determine the stellar mass of each photometric component in each galaxy. We determine the $M_{\rm BH} - M_{\rm bulge}$ relation using a total of 12 dwarf galaxies hosting broad-line AGNs, along with a comparison sample of 88 galaxies with dynamical BH masses and 37 reverberation-mapped AGNs. We find a strong correlation between BH mass and bulge mass with ${\rm log}(M_{\rm BH}/M_\odot) = (1.24\pm 0.08)~{\rm log}(M_{\rm bulge}/10^{11} M_\odot) + (8.80\pm 0.09)$. The near-linear slope and normalization are in good agreement with correlations found previously when only considering higher mass systems. This work has quadrupled the number of dwarf galaxies on the BH-bulge mass relation, with implications for BH seeding and predictions for gravitational wave detections of merging BHs at higher redshifts with $LISA$.
In this paper, we try to understand why the classical bulge fraction observed in S0 galaxies is significantly higher than that in spiral galaxies. We carry out a comparative study of the bulge and global properties of a sample of spiral and S0 galaxies in a fixed environment. Our sample is flux limited and contains 262 spiral and 155 S0 galaxies drawn from the Sloan Digital Sky Survey. We have classified bulges into classical and pseudobulge categories based on their position on the Kormendy diagram. Dividing our sample into bins of galaxy stellar mass, we find that the fraction of S0 galaxies…
In this work, we investigate the reason behind the increased occurrence of S0 galaxies in high density environments. Our sample comprises of $\sim$ 2500 spiral and $\sim$ 2000 S0 galaxies spanning a wide range of environments. Dividing the galaxies into categories of classical and pseudobulge hosting spiral and S0 galaxies, we have studied their properties as a function of the environment. We find that the fraction of pseudobulge hosting disc galaxies decreases with increase in density. The classical bulge hosting spirals and S0 galaxies follow a similar trend in less dense environments but to…
We present observations of pseudobulges in S0 and spiral galaxies using imaging data taken with the Spitzer Infra-Red Array Camera. We have used 2-d bulge-disk-bar decomposition to determine structural parameters of 185 S0 galaxies and 31 nearby spiral galaxies. Using the Sersic index and the position on the Kormendy diagram to classify their bulges as either classical or pseudo, we find that 25 S0s (14%) and 24 spirals (77%) host pseudoblges. The fraction of pseudobulges we find in spiral galaxies is consistent with previous results obtained with optical data and show that the evolution of a …
We report the discovery of a rare compact early-type galaxy, SDSS J085431.18+173730.5 (hereafter cE\_AGN). It has an half light radius of R$_{e}$ = 490 pc and a brightness of M$_{r}$ = $-$18.08 mag. Optical spectroscopy available from the Sloan Digital Sky Survey (SDSS) reveals the presence of prominent broad-line emissions with the H$α$ broad component width of FWHM=2400 km/s. The black hole (BH) mass, as estimated from the luminosity and width of the broad H$α$ emission, is 2.1$\times$10$^{6}$ M$_{\sun}$. With the help of surface photometry, we perform a detailed analysis of the structural p…
We present the discovery of rare active galactic nuclei (AGNs) in nearby (z < 0.05) compact elliptical galaxies (cEs) located in isolated environments. Using spectroscopic data from the Sloan Digital Sky Survey (SDSS) Data Release 12, four AGNs were identified based on the optical emission-line diagnostic diagram. SDSS optical spectra of AGNs show the presence of distinct narrow-line emissions. Utilizing the black hole (BH) mass-stellar velocity dispersion scaling relation and the correlation between the narrow L([OIII])/L(H\b{eta}) line ratio and the width of the broad Hα emission line, we es…
We use bulge-type classifications of 809 representative SDSS galaxies by Gadotti (2009) to classify a large sample of galaxies into real bulges (classical or elliptical) and pseudobulges using Random Forest. We use structural and stellar population predictors that can easily be measured without image decomposition. Multiple parameters such as the central mass density with 1 kpc, concentration index, Sérsic index and velocity dispersion do result in accurate bulge classifications when combined together. We classify $\sim 44,500$ face-on galaxies above stellar mass of 10$^{10}$ M$_\odot$ and red…
We report the multi-wavelength properties of millimeter galaxies hosting X-ray detected active galactic nuclei (AGNs) from the ALMA Lensing Cluster Survey (ALCS). ALCS is an extensive survey of well-studied lensing clusters with ALMA, covering an area of 133 arcmin$^2$ over 33 clusters with a 1.2 mm flux-density limit of ${\sim}$60 $\mathrm{μJy}$ ($1σ$). Utilizing the archival data of Chandra, we identify three AGNs at $z=$1.06, 2.09, and 2.84 among the 180 millimeter sources securely detected in the ALCS (of which 155 are inside the coverage of Chandra). The X-ray spectral analysis shows that…
It is commonly accepted that radio-loud active galactic nuclei are hosted exclusively by giant elliptical galaxies. We analyze high-resolution optical Hubble Space Telescope images of a sample of radio galaxies with extended double-lobed structures associated with disk-like optical counterparts. After systematically evaluating the probability of chance alignment between the radio lobes and the optical counterparts, we obtain a sample of 18 objects likely to have genuine associations. The host galaxies have unambiguous late-type morphologies, including spiral arms, large-scale dust lanes among …
Dissecting the 3D chemo-dynamical structures of NGC~1381: A galaxy hosting an ancient slow bar with an accretion-related bulge and thick disc
Westlake University（西湖大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Astrophysics Research Institute, Liverpool John Moores University（利物浦约翰摩尔斯大学天体物理研究所）；Instituto de Astrofísica de Canarias（加那利天体物理学研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕尔马大学天体物理学系）；Department of Astrophysics, University of Vienna（维也纳大学天体物理学系）
The formation and evolutionary processes of galaxy bulges are still unclear, and the presence of young stars in the bulge of the Milky Way is largely debated. We recently demonstrated that Terzan 5, in the Galactic bulge, is a complex stellar system hosting stars with very different ages and a striking chemical similarity to the field population. This indicates that its progenitor was likely one of the giant structures that are thought to generate bulges through coalescence. Here we show that another globular cluster-like system in the bulge (Liller 1) hosts two distinct stellar populations wi…
We investigate the relation of black hole mass versus host stellar mass and that of mass accretion rate versus star formation rate (SFR) in moderately luminous ($\log L_{\rm bol} \sim 44.5-46.5\ {\rm erg\ s^{-1}}$), X-ray selected broad-line active galactic nuclei (AGNs) at $z=1.18-1.68$ in the Subaru/XMM-Newton Deep Field. The far-infrared to far-ultraviolet spectral energy distributions of 85 AGNs are reproduced with the latest version of Code Investigating GALaxy Emission ({\tt CIGALE}), where the AGN clumpy torus model {\tt SKIRTOR} is implemented. Most of their hosts are confirmed to be m…
Galactic nuclei, like the one of the Milky Way, are extreme places with high stellar densities and, in most cases, hosting a supermassive black hole. One of the scenarios proposed for the formation of the Galactic nucleus is by merging of primordial globular clusters (Capuzzo-Dolcetta 1993). An implication of this model is that this region should host stars characteristically found in old Milky Way globular clusters. RR Lyrae stars are primary distance indicators, well known representatives of old and metal-poor stellar populations, and therefore regularly found in globular clusters. Here we r…
The origin of the quenching in galaxies is still highly debated. Different scenarios and processes are proposed. We use multi-band (400-1600 nm) bulge-disc decompositions of massive galaxies in the redshift range 0<z<2 to explore the distribution and the evolution of galaxies in the log SFR-logM* plane as a function of the stellar mass-weighted bulge-to-total ratio (BTM) and also for internal galaxy components (bulge/disc) separately. We find evidence of a clear link between the presence of a bulge and the flattening of the Main Sequence in the high-mass end. All bulgeless galaxies (BTM<0.2) l…
We present HST images for nine megamaser disk galaxies with the primary goal of studying photometric BH-galaxy scaling relations. The megamaser disks provide the highest-precision extragalactic BH mass measurements, while our high-resolution HST imaging affords us the opportunity to decompose the complex nuclei of their late-type hosts in detail. Based on the morphologies and shapes of the galaxy nuclei, we argue that most of these galaxies' central regions contain secularly evolving components (pseudo-bulges), and in many cases we photometrically identify co-existing "classical" bulge compone…
We analyze central surface brightness mu_0, nuclear and global colors of intermediate redshift disk galaxies. On an apparent-diameter limited sample of 398 galaxies from ACS/HST Great Observatories Origins Deep Survey North (GOODS-N), we find 131 galaxies with bulges and 214 without. Up to z ~ 0.8, blue, star-forming nuclei are found in galaxies with low mu_0 only; all high-mu_0 nuclei show red, passive colors, so that nuclear and global (U - B) colors strongly correlate with central surface brightness, as found in the local Universe. At 0.8 < z < 1.3, a fraction ~ 27% of the high-surface brig…
(Abridged) We study the incidence, as well as the nature, of composite bulges in a sample of 10 face-on barred galaxies to constrain the formation and evolutionary processes of the central regions of disk galaxies. We analyze the morphological, photometric, and kinematic properties of each bulge. Then, by using a case-by-case analysis we identify composite bulges and classify every component into a classical or pseudobulge. In addition, bar-related boxy/peanut (B/P) structures were also identified and characterised. We find only three galaxies hosting a single-component bulge (two pseudobulges…
Establishing a correlation (or lack thereof) between the bimodal colour distribution of galaxies and their structural parameters is crucial to understand the origin of bimodality. To achieve that, we have performed 2D mass-based structural decomposition (bulge+disc) of all disc galaxies (total$=$1263) in the Herschel imaging area of the Stripe 82 region using $K_s$ band images from the VICS82 survey. The scaling relations thus derived are found to reflect the internal kinematics and are employed in combination to select an indubitable set of classical and pseudo bulge hosting disc galaxies. Th…
Nucleation is a common phenomenon in all types of galaxies and at least 70% of them host nuclear star clusters (NSCs) in their centres. Many of the NSCs co-habit with super-massive black holes and follow similar scaling relations with host galaxy properties. NSCs, unlike black holes, preserve the signature of their evolutionary path imprinted onto their kinematics and stellar populations. Thus their study provides us with important information about the formation of galactic nuclei. In this paper we explored the angular momentum of the nuclei of six intermediate mass (9.7 > log(Mdyn/M_sun) > 1…
Most present-day galaxies with stellar masses $\geq10^{11}$ solar masses show no ongoing star formation and are dense spheroids. Ten billion years ago, similarly massive galaxies were typically forming stars at rates of hundreds solar masses per year. It is debated how star formation ceased, on which timescales, and how this "quenching" relates to the emergence of dense spheroids. We measured stellar mass and star-formation rate surface density distributions in star-forming galaxies at redshift 2.2 with $\sim1$ kiloparsec resolution. We find that, in the most massive galaxies, star formation i…
Major galaxy mergers can trigger nuclear activities and are responsible for high-luminosity quasi-stellar objects /active galactic nuclei (QSOs/AGNs). In certain circumstances, such mergers may cause dual active galactic nuclei (dAGN) phenomenon. This study investigates dAGN triggering and evolution of massive black holes (MBHs) during the merging processes using hydrodynamic code GADGET-2 to simulate several gas-rich major mergers at redshift $z=2$ and $3$, respectively. Results reveal that gas-rich major mergers can trigger significant nuclear activities after the second and third pericentri…
We present a list of 220 face-on, almost bulgeless galaxies assumed to be counterparts to the objects from the Reference Flat Galaxy Catalog (RFGC). We selected the Sc, Scd and Sd-type galaxies according to their apparent axial ratio $log(r_{25}) < 0.05$ and major standard angular diameter $log(d_{25}) > 0.90$ as defined in HyperLEDA. The sample objects are restricted by the radial velocity $V_{LG} < 10000$ km/s and a declination of above $-30$ deg. The morphological composition of our sample is quite similar to that of RFGC. We notice the following common properties of face-on bulgeless galax…
Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey
Indian Institute of Science Education and Research, Bhopal（印度科学教育研究所博帕尔分校）；Indian Institute of Astrophysics, Bangalore（班加罗尔天体物理研究所）；Observatoire de Paris, LERMA, College ‘ de France, PSL University, Sorbonne University, CNRS, Paris（巴黎天文台，LERMA，法兰西学院，PSL大学，索邦大学，法国国家科学研究中心，巴黎）；Siebel School of Computing and Data Science, University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校赛布尔计算与数据科学学院）；Birla Institute of Technology & Science, Goa（戈亚邦比尔拉理工科学与艺术学院）；HappyMonk AI
Detailed imaging and spectroscopic analysis of the centers of nearby S0 and spiral galaxies shows the existence of "composite bulges", where both classical bulges and disky pseudobulges coexist in the same galaxy. As part of a search for supermassive black holes in nearby galaxy nuclei, we obtained VLT-SINFONI observations in adaptive-optics mode of several of these galaxies. Schwarzschild dynamical modeling enables us to disentangle the stellar orbital structure of the different central components, and to distinguish the differing contributions of kinematically hot (classical bulge) and kinem…
Spiral-driven instabilities may drive gas inflow to enhance central star formation in disk galaxies. We investigate this hypothesis using the Sloan Digital Sky Survey (SDSS) in a sample of 2779 nearby unbarred star-forming main-sequence spiral galaxies. The strength of spiral arms is quantified by their average Fourier amplitude relative to the axisymmetric disk. The star formation properties in the central 1--3\,kpc region were derived from the SDSS spectra. We show that galaxies with stronger spiral arms not only tend to have more intense central specific star formation rate (sSFR), larger B…
We present a study of 41 dwarf galaxies hosting active massive black holes (BHs) using Hubble Space Telescope observations. The host galaxies have stellar masses in the range of $M_\star \sim 10^{8.5}-10^{9.5}~M_\odot$ and were selected to host active galactic nuclei (AGNs) based on narrow emission line ratios derived from Sloan Digital Sky Survey spectroscopy. We find a wide range of morphologies in our sample including both regular and irregular dwarf galaxies. We fit the HST images of the regular galaxies using GALFIT and find that the majority are disk-dominated with small pseudobulges, al…
We study the cosmological build-up of pseudobulges using the LGalaxies semi-analytical model for galaxy formation with a new approach for following separately the assembly of classical bulges and pseudobulges. Classical bulges are assumed to be the result of violent processes (i.e., mergers and starbursts), while the formation of pseudobulges is connected to the secular growth of disks. We apply the model to both the Millennium and the Millennium II simulations, in order to study our results across a wide range of stellar masses ($10^{7} - 10^{11.5} M_{\odot}$). We find that $z=0$ pseudobulges…
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 black holes (wBHs) by using the semi-analytical model LGalaxies run on top of Millennium merger trees. We track spin changes that BHs experience during both coalescence events and gas accretion phases. For the latter, we assume that spin changes are coupled with the bulge assembly. This assumption leads to predictions for the median spin values of z=0 BHs that depend on whether they are hosted by pseudobulges…
We study the structural properties of Low Surface Brightness galaxies (LSB) using a sample of 263 galaxies observed by the Green Bank Telescope (Schneider et al 1992). We perform 2D decompositions of these galaxies in the SDSS $g$, $r$ and $i$ bands using the GALFIT software. Our decomposition reveals that about $60\%$ of these galaxies are bulgeless i.e., their light distributions are well modelled by pure exponential disks. The rest of the galaxies were fitted with two components: a Sersic bulge and an exponential disk. Most of these galaxies have bulge-to-total (B/T) ratio less than 0.1. Ho…
Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). A binary companion is increasingly gaining support as a dominant shaping mechanism, however morphological studies of the few PNe that we know for certain were shaped by binary evolution are scarce or biased. Newly discovered binary central stars (CSPN) from the OGLE-III photometric variability survey have significantly increased the sample of post common-envelope (CE) nebulae available for morphological analysis. We pr…
We report the discovery of an active intermediate-mass black hole (IMBH) candidate in the center of nearby barred bulgeless galaxy $\rm NGC~3319$. The point X-ray source revealed by archival Chandra and XMM-Newton observations is spatially coincident with the optical and UV galactic nuclei from Hubble Space Telescope observations. The spectral energy distribution derived from the unresolved X-ray and UV-optical flux is comparable with active galactic nuclei (AGNs) rather than ultra-luminous X-ray sources, although its bolometric luminosity is only $3.6\times10^{40}~\rm erg~s^{-1}$. Assuming an…
We present multi-component decomposition of high-quality $R$-band images of 312 disk galaxies from the Carnegie-Irvine Galaxy Survey. In addition to bulges and disks, we successfully model nuclei, bars, disk breaks, nuclear/inner lenses, and inner rings. Our modeling strategy treats nuclear rings and nuclear bars as part of the bulge component, while other features such as spiral arms, outer lenses, and outer rings are omitted from the fits because they are not crucial for accurate bulge measurements. The error budget of bulge parameters includes the uncertainties from sky level measurements a…
We present a series of $N$-body simulations representing the evolution of a galactic nucleus and its stellar content in a nearly one-to-one representation. The aim of this suite of simulations is to shed light on the interplay between nuclear clusters (NCs), super-massive black holes (SMBH) and the galactic nuclei in which they are contained. We modelled galaxies with masses from few times $10^8$ to $10^{11}$ M$_\odot$, hosting in their nucleus a number of globular clusters and, in some cases, a central SMBH.
We produce a kinematic analysis of AGN-hosting cluster galaxies from a sample 33 galaxy clusters selected using the X-ray Clusters Database (BAX) and populated with galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). The 33 galaxy clusters are delimited by their relative intensity of member galaxy substructuring as a proxy to core merging to derive two smaller sub-samples of 8 dynamically active (merging) and 25 dynamically relaxed (non-merging) states. The AGN were selected for each cluster sub-sample by employing the WHAN diagram to the strict criteria of log$_{10}$([NII]…
Observational searches for intermediate-mass black holes (IMBHs; $10^2 - 10^6$ $M_\odot$) include relatively isolated dwarf galaxies. For those that host active galactic nuclei (AGNs), the IMBH nature may be discerned through the accretion - jet activity. We present radio observations of four AGN-hosting dwarf galaxies (which potentially harbor IMBHs). Very large array (VLA) observations indicate steep spectra (indices of $-$0.63 to $-$1.05) between 1.4 and 9 GHz. A comparison with the 9 GHz in-band spectral index however shows a steepening for GH047 and GH158 (implying older/relic emission) a…
Galaxy-SMBH co-evolution in 2,435 DESI disk galaxies and merger-free BH growth in bulgeless disks
University of Oxford（牛津大学）；Lancaster University（兰卡斯特大学）；University of Edinburgh（爱丁堡大学）；Masaryk University（马萨里克大学）；University of Toronto（多伦多大学）；University of Louisville（路易斯维尔大学）；Haverford College（哈弗福德学院）；University of Utah（犹他大学）
We present detailed image analysis of rest-frame optical images of 235 low-redshift ($z \leq$ 0.35) type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope. The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion gala…
A three-dimensional dynamical model for a galaxy hosting a BL Lacertae object is constructed. The model consists of a logarithmic potential representing an elliptical host galaxy with a bulge of radius $c_b$ and a dense massive nucleus. Using numerical experiments, we try to distinguish between regular and chaotic motion in both 2D and 3D system. In particular, we investigate how the basic parameters of our model, such as the mass of the nucleus, the internal perturbation and the flattening parameters influence the amount and the degree of chaos. Interesting correlations are presented for both…
The mass estimator used to calculate black hole (BH) masses in broad-line active galactic nuclei (AGNs) relies on a virial coefficient (the "$f$ factor") that is determined by comparing reverberation-mapped (RM) AGNs with measured bulge stellar velocity dispersions against the $M_{\rm BH}-σ_*$ relation of inactive galaxies. It has recently been recognized that only classical bulges and ellipticals obey a tight $M_{\rm BH}-σ_*$ relation; pseudobulges have a different zero point and much larger scatter. Motivated by these developments, we reevaluate the $f$ factor for RM AGNs with available $σ_*…
The vast majority of optically identified active galactic nuclei (AGNs) in the local Universe reside in host galaxies with prominent bulges, supporting the hypothesis that black hole formation and growth is fundamentally connected to the build-up of galaxy bulges. However, recent mid-infrared spectroscopic studies with Spitzer of a sample of optically "normal" late-type galaxies reveal remarkably the presence of high-ionization [NeV] lines in several sources, providing strong evidence for AGNs in these galaxies. We present follow-up X-ray observations recently obtained with XMM-Newton of two s…
We have conducted a high-resolution spectroscopic study using Spitzer of 18 bulgeless (Sd/Sdm) galaxies that show no definitive signatures of nuclear activity in their optical spectra. This is the first systematic mid-IR search for weak or hidden AGNs in a statistically significant sample of bulgeless disk galaxies. Based on the detection of the high-ionization [NeV] line, we report the discovery of an AGN in one out of the 18 galaxies in the sample. This galaxy, NGC 4178, is a nearby edge-on Sd galaxy, which likely hosts a prominent nuclear star cluster (NSC). The bolometric luminosity of the…
The complex relationships between AGN, bars and bulges
Masaryk University（马萨里克大学）；Lancaster University（兰卡斯特大学）；University of Minnesota（明尼苏达大学）；University of Toronto（多伦多大学）；University of Oxford（牛津大学）；European Space Agency (ESA)（欧洲空间局）
Although there have been numerous studies of chemical abundances in the Galactic bulge, the central two degrees have been relatively unexplored due to the heavy and variable interstellar extinction, extreme stellar crowding, and the presence of complex foreground disk stellar populations. In this paper we discuss the metallicity distribution function, vertical and radial gradients and chemical abundances of $α$-elements in the inner two degrees of the Milky Way, as obtained by recent IR spectroscopic surveys. We use a compilation of recent measurements of metallicities and $α$-element abundanc…
We present combined evolution of morphological and stellar properties of galaxies on the two sides of z=2 (2.0<z<4.0 and 1.5<z<2.0) in CDFS, with ground-based spectroscopic redshifts. We perform bulge-disc decomposition on their images in J and H filters, from the 3DHST Legacy Survey obtained using HST/WFC3. Combining morphological information with stellar properties, we provide a detailed account of the formation/growth of discs and spheroids around z~2. The fraction of 2-component (bulge+disc) systems increases from ~46% for z>2 to ~70% for z<2, compensating for the fall in population of pur…
We probed the relation between properties of Seyfert nuclei and morphology of their host galaxies. We selected Seyfert galaxies from the Sloan Digital Sky Survey with redshifts less 0.2 identified by the Véron Catalog (13th). We used the "{\it{FracDev}}" parameter from SDSS galaxy fitting models to represent the bulge fractions of the Seyfert host galaxies. We found that the host galaxies of Seyfert 1 and Seyfert 2 are dominated by large bulge fractions, and Seyfert 2 galaxies are more likely to be located in disk galaxies whereas most of the Seyfert 1 galaxies are located in bulge-dominant ga…
Bar Evolution in Edge-on Galaxies: A Demographic Study of Boxy/Peanut Bulges
Indian Institute of Science Education and Research, Bhopal（印度科学教育研究所博帕尔分校）；Universidad Andrés Bello（安德烈斯贝略大学）；Indian Institute of Astrophysics（印度天体物理研究所）
We report the discovery of a 20-kpc-sized Hα emission in SDSS J083803.68+540642.0, a ringed dwarf galaxy (M$_V$ = -17.89 mag) hosting an accreting intermediate-mass black hole at z=0.02957. Analysis of the HST images indicates that it is an early-type galaxy with a featureless low-surface brightness disk (μ0 = 20.39 mag arcsec$^{-2}$ in the V band) and a prominent, relatively red bulge (V - I = 2.03, Re = 0.28 kpc or 0."48) that accounts for ~81% of the total light in the I band. A circumgalactic ring of a diameter 16 kpc is also detected, with a disperse shape on its south side. The optical e…
We reason that, without physical fine-tuning, neither the supermassive black holes (SMBHs) nor the stellar bulges can self-regulate or inter-regulate by driving away already fallen cold gas to produce the observed correlation between them. We suggest an alternative scenario where the observed mass ratios of the SMBHs to bulges reflect the angular momentum distribution of infallen gas such that the mass reaching the stable accretion disc is a small fraction of that reaching the bulge region, averaged over the cosmological time scales. We test this scenario using high resolution, large-scale cos…
Mid-Infrared Outbursts in Nearby Galaxies: Nuclear Obscuration and Connections to Hidden Tidal Disruption Events and Changing-Look Active Galactic Nuclei
Several recent papers have reported on the occurrence of active galactic nuclei (AGN) containing under-massive black holes relative to a linear scaling relation between black hole mass (M_bh) and host spheroid stellar mass (M_sph,*). Dramatic revisions to the M_bh-M_sph,* and M_bh-L_sph relations, based on samples containing predominantly inactive galaxies, have however recently identified a new steeper relation at M_bh < (2-10)x10^8 M_Sun, roughly corresponding to M_sph,* < (0.3-1)x10^{11} M_Sun. We show that this steeper, quadratic-like M_bh-M_sph,* relation defined by the Sersic galaxies, i…
