We study star formation rates (SFR) and stellar masses in bulges of nearby disk galaxies, using SFRs and stellar masses derived from Spitzer and GALEX data. At present day SFR the median pseudobulge could have grown the present day stellar mass in 8 Gyr. In almost all galaxies in our sample the specific SFR (SFR per unit stellar mass) of the bulge is higher than that of the outer disk, suggesting that almost all galaxies are increasing their B/T through internal star formation. In pseudobulges, SFR density correlates, positvely, with mass density, this is consistent with that stellar mass being formed by moderate, extended star fromation. As well, SFR density and stellar mass of pseudobulges are shown to be correlated with the stellar mass of the outer disk. Classical bulges have the lowest specific SFR implying a growth times that are longer than a Hubble time. We identify a class of bulges that have nuclear morphology similar to pseudobulges, significantly lower specific SFR than pseudobulges, and are closer to classical bulges in structural parameter correlations. Our results are consistent with a scenario in which bulge growth via internal star formation is a natural, and near ubiquitous phenomenon in disk galaxies. Some disk galaxies with out a large classical bulge, over long periods of extended star formation are able to growth a pseudobulge. In this sense, galaxies with pseudobulges may very well be bulgeless (or "quasi-bulgeless") galaxies, and galaxies with classical bulges are galaxies in which both internal evolution and hierarchical merging are responsible for the bulge mass by fractions that vary from galaxy-to-galaxy. [Abridged]
We investigate scaling relations of bulges using bulge-disk decompositions at 3.6 micron and present bulge classifications for 173 E-Sd galaxies within 20 Mpc. Pseudobulges and classical bulges are identified using Sersic index, HST morphology, and star formation activity (traced by 8 micron emission). In the near-IR pseudobulges have n_b<2 and classical bulges have n_b>2, as found in the optical. Sersic index and morphology are essentially equivalent properties for bulge classification purposes. We confirm, using a much more robust sample, that the Sersic index of pseudobulges is uncorrelated…
Some S0 and early-type spiral galaxies possess "composite bulges"; in these galaxies, the photometric bulge -- the central stellar light in excess of the disk light -- is composed of both a "(disky) pseudobulge", with a flattened, disklike morphology and relatively cool stellar kinematics, and a rounder, kinematically hot "classical bulge" embedded within. I speculate that supermassive black holes (SMBH) in such galaxies may correlate with the classical-bulge component only, and not with the pseudobulge component; preliminary comparisons with SMBH masses appear to support this hypothesis.
In this Letter, we present a systematic study of lenticular (S0) galaxies based on mid-infrared imaging data on 185 objects taken using the Spitzer Infra Red Array Camera. We identify the S0s hosting pseudobulges based on the position of the bulge on the Kormendy diagram and the Sérsic index of the bulge. We find that pseudobulges preferentially occur in the fainter luminosity class (defined as having total K-band absolute magnitude M_K fainter than -22.66 in the AB system). We present relations between bulge and disk parameters obtained as a function of the bulge type. The disks in the pseudo…
We present an inventory of galaxy bulge types (elliptical galaxy, classical bulge, pseudobulge, and bulgeless galaxy) in a volume-limited sample within the local 11 Mpc volume using Spitzer 3.6 micron and HST data. We find that whether counting by number, star formation rate, or stellar mass, the dominant galaxy type in the local universe has pure disk characteristics (either hosting a pseudobulge or being bulgeless). Galaxies that contain either a pseudobulge or no bulge combine to account for over 80% of the number of galaxies above a stellar mass of 10^9 M_sun. Classical bulges and elliptic…
We present HST/ACS observations of ten galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point source (AGN), a bulge, and a disk, and fitted the bulge with a Sersic profile and the disk with an exponential profile. We find that at least five galaxies can be classified as having pseudobulges. All ten galaxies lie below the \mbh--L$_{bulge}$ relation, confirming earlier results. Their locus is similar to that occupied by pseudobulges. This leads us to conc…
It is now well established that all galaxies with a massive bulge component harbour a central supermassive black hole (SMBH). The mass of the SMBH correlates with bulge properties such as the bulge mass and the velocity dispersion, which implies that the bulge and the SMBH of a galaxy have grown together during the formation process. The spiral galaxy NGC3368 and the S0 galaxy NGC3489 both host a pseudobulge and a much smaller classical bulge component at the centre. We present high resolution, near-infrared IFU data of these two galaxies, taken with SINFONI at the VLT, and use axisymmetric or…
Bulges in spiral galaxies have been supposed to be classified into two types: classical bulges or pseudobulges. Classical bulges are thought to form by galactic merger with bursty star formation, whereas pseudobulges are suggested to form by secular evolution due to spiral arms and a barred structure funneling gas into the galactic centre. Noguchi (1998,1999) suggested another bulge formation scenario, `clump-origin bulge'. He demonstrated using a numerical simulation that a galactic disc suffers dynamical instability to form clumpy structures in the early stage of disc formation since the pre…
Bulges in spiral galaxies have been supposed to be classified into two types: classical bulges or pseudobulges. Classical bulges are thought to form by galactic merger with bursty star formation, whereas pseudobulges are suggested to form by secular evolution. Noguchi (1998, 1999) suggested another bulge formation scenario, `clump-origin bulge'. He demonstrated using a numerical simulation that a galactic disc forms clumpy structures in the early stage of disc formation, then the clumps merge into a single bulge at the centre. I perform a high-resolution N-body/SPH simulation for the formation…
We present a study of the host bulge properties and their relations with the black hole mass on a sample of 10 intermediate-type active galactic nuclei (AGN). Our sample consists mainly of early type spirals, four of them hosting a bar. For 70$^{+10}_{-17}%$ of the galaxies we have been able to determine the type of the bulge, and find that these objects probably harbor a pseudobulge or a combination of classical bulge/ pseudobulge, suggesting that pseudobulges might be frequent in intermediate-type AGN. In our sample, 50\pm14% of the objects show double-peaked emission lines. Therefore, narro…
The masses of supermassive black holes are known to correlate with the properties of the bulge components of their host galaxies. In contrast, they appear not to correlate with galaxy disks. Disk-grown pseudobulges are intermediate in properties between bulges and disks. It has been unclear whether they do or do not correlate with black holes in the same way that bulges do, because too few pseudobulges were classified to provide a clear result. At stake are conclusions about which parts of galaxies coevolve with black holes, possibly by being regulated by energy feedback from black holes. Here…
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 study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses < 10^6 solar mass. Based on careful image decomposition of a snapshot Hubble Space Telescope I-band survey, we found that these BHs are found predominantly in galaxies with pseudobulges. Here we show that the \mbulge\ relation for the pseudobulges at low mass is significantly different from classical bulges with BH masses >10^7 solar mass. Specfically, bulges span a much wider range of bulge luminosity, and on average the luminosity is larger, at fixed black hole mass. The trend hold…
Bulges can be classified into classical and pseudobulges; the former are considered to be end products of galactic mergers and the latter to form via secular evolution of galactic disks. Observationally, bulges of disk galaxies are mostly pseudobulges, including the Milky Way's. We here show, by using self-consistent cosmological simulations of galaxy formation, that the formation of pseudobulges of Milky Way-sized disk galaxies has mostly completed before disk formation; thus the main channel of pseudobulge formation is not secular evolution of disks. Our pseudobulges form by rapid gas supply…
More than half of nearby disc galaxies have pseudobulges instead of classical bulges that are though to be end-products of galaxy mergers. Pseudobulges are presumed to develop overtime as a result of secular evolution of galaxy discs. We report simulations of galaxy formation, in which two disc galaxies with disky pseudobulges have formed. Based on the profile decomposition, the bulge-to-total mass ratio of the simulated galaxies is 0.6 for one galaxy and 0.3 for the other. We find that the main formation mechanism of the pseudobulges in our simulations is not the secular evolution of discs bu…
Numerical simulations show that box-shaped bulges of edge-on galaxies are not bulges: they are bars seen side-on. Therefore the two components that are seen in edge-on Sb galaxies such as NGC 4565 are a disk and a bar. But face-on SBb galaxies always show a disk, a bar, and a (pseudo)bulge. Where is the (pseudo)bulge in NGC 4565? We use archival Hubble Space Telescope H-band images and Spitzer Space Telescope 3.6 micron wavelength images, both calibrated to 2MASS K_s band, to penetrate the prominent dust lane in NGC 4565. We find a high surface brightness, central stellar component that is cle…
We present a sample of edge-on spiral galaxies both of early and late types.The sample consists of 175 galaxies in the Ks-filter, 169 galaxies in the H-filter and 165 galaxies in the J-filter. Bulge and disc decompositions of each galaxy image, taken from the Two Micron All Sky Survey (2MASS), were performed. We discuss several scaling relations for bulges and discs which indicate a tight link between their formation and evolution. We show that galaxies with bulges fitted by the Sersic index n<2 (pseudobulges) have quite different distributions of their structural parameters than galaxies with…
We use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly-Telescope (HET) to study the kinematics of pseudobulges and classical bulges in the nearby universe. We present major-axis rotational velocities, velocity dispersions, and h3 and h4 moments derived from high-resolution (sigma ~ 39 km/s) spectra for 45 S0 to Sc galaxies; for 27 of the galaxies we also present minor axis data. We combine our kinematics with bulge-to-disk decompositions. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on Sérsic…
There is mounting evidence that a significant fraction of Black Holes (BHs) today live in late-type galaxies, including bulge-less galaxies and those hosting pseudobulges, and are significantly undermassive with respect to the scaling relations followed by their counterpart BHs in classical bulges of similar stellar (or even bulge) mass. Here we discuss the predictions of two state-of-the-art hierarchical galaxy formation models in which BHs grow via mergers and, in one, also via disk instability. Our aim is to understand if the wealth of new data on local BH demography is consistent with stan…
Using HST observations of 147 host galaxies of low-mass black holes (BHs), we systematically study the structures and scaling relations of these active galaxies. Our sample is selected to have central BHs with virial masses ~10^5-10^6 solar mass. The host galaxies have total I-band magnitudes of -23.2<M_I<-18.8 mag and bulge magnitudes of -22.9<M_I<-16.1 mag. Detailed bulge-disk-bar decompositions with GALFIT show that 93% of the galaxies have extended disks, 39% have bars and 5% have no bulges at all at the limits of our observations. Based on the Sersic index and bulge-to-total ratio, we con…
We investigate the formation and evolution of the pseudobulge in "Eris", a high-resolution N-body + smoothed particle hydrodynamics (SPH) cosmological simulation that successfully reproduces a Milky Way-like massive late-type spiral in a cold dark matter (LCDM) universe. At the present epoch, Eris has a virial mass Mvir=8x10^11 Msun, a photometric stellar mass M*=3.2x10^10 Msun, a bulge-to-total ratio B/T = 0.26, and a weak nuclear bar. We find that the bulk of the pseudobulge forms quickly at high redshift via a combination of non-axisymmetric disk instabilities and tidal interactions or merg…
We present a mid-IR investigation of the scaling relations between supermassive black hole masses (MBH) and the structural parameters of the host spheroids in local galaxies. The work is based on two-dimensional bulge-disk decompositions of Spitzer/IRAC 3.6 um images of 57 galaxies with MBH estimates. Our estimates of effective radii (Re) and surface brightnesses, combined with velocity dispersions (sigma) from the literature, define a FP relation consistent with previous determinations but doubling the observed range in Re. None of our galaxies is an outlier of the FP, demonstrating the accur…
We use N-body chemo-dynamic simulations to study the coupling between morphology, kinematics and metallicity of the bar/bulge region of our Galaxy. We make qualitative comparisons of our results with available observations and find very good agreement. We conclude that this region is complex, since it comprises several stellar components with different properties -- i.e. a boxy/peanut bulge, thin and thick disc components, and, to lesser extents, a disky pseudobulge, a stellar halo and a small classical bulge -- all cohabiting in dynamical equilibrium. Our models show strong links between kine…
We present GMRT 1280 MHz radio continuum observations and follow-up optical studies of the disk and nuclear star formation in a sample of low luminosity bulgeless galaxies. The main aim is to understand bulge formation and overall disk evolution in these late type galaxies. We detected radio continuum from five of the twelve galaxies in our sample; the emission is mainly associated with disk star formation. Only two of the detected galaxies had extended radio emission; the others had patchy disk emission. In the former two galaxies, NGC3445 and NGC4027, the radio continuum is associated with s…
Observations reveal a strong structural coupling between bulge and disc in S0 galaxies, which seems difficult to explain if they have formed from supposedly catastrophic events such as major mergers. We face this question by quantifying the bulge-disc coupling in dissipative simulations of major and minor mergers that result in realistic S0s. We have studied the dissipative N-body binary merger simulations from the GalMer database that give rise to realistic, relaxed E/S0 and S0 remnants (67 major and 29 minor mergers). We simulate surface brightness profiles of these S0-like remnants in the K…
Stellar bars are important for the secular evolution of disk galaxies because they can drive gas into the galactic central regions. To investigate the star formation properties in barred galaxies, we presented a multi-wavelength study of two barred galaxies NGC 2903 and NGC 7080. We performed the three-component bulge-disk-bar decomposition using the 3.6 μm images, and identified the bulges in the two galaxies as pseudobulges. Based on the narrowband Hα images, the star formation clumps were identified and analyzed. the clumps in the bulge regions have the highest star formation rate surface d…
In this paper we present gas density, star formation rate, stellar masses, and bulge disk decompositions for a sample of 60 galaxies. Our sample is the combined sample of BIMA SONG, CARMA STING, and PdBI NUGA surveys. We study the effect of using CO-to-H_2 conversion factors that depend on the CO surface brightness, and also that of correcting star formation rates for diffuse emission from old stellar populations. We estimate that star formation rates in bulges are typically lower by 20% when correcting for diffuse emission. We find that over half of the galaxies in our sample have molecular g…
Using three fiducial Nbody+SPH simulations, we follow the merging of two disk galaxies with a hot gaseous halo component each, and examine whether the merger remnant can be a spiral galaxy. The stellar progenitor disks are destroyed by violent relaxation during the merging and most of their stars form a classical bulge, while the remaining form a thick disk and its bar. A new stellar disk forms subsequently and gradually in the remnant from the gas accreted mainly from the halo. It is vertically thin and well extended in its equatorial plane. A bar starts forming before the disk is fully in pl…
Double-barred galaxies are common in the local Universe, with approximately one third of barred spirals hosting an smaller, inner bar. Nested bars have been proposed as a mechanism for transporting gas to the very central regions of the galaxy, trigger star formation and contribute to the growth of the bulge. To test this idea, we perform for the first time a detailed analysis of the photometry, kinematics and stellar populations of a double-barred galaxy: NGC 357. We find that this galaxy is either hosting a pseudobulge or a classical bulge together with an inner disc. We compare the relative…
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…
The growth of supermassive black holes appears to be driven by galaxy mergers, violent merger-free processes and/or `secular' processes. In order to quantify the effects of secular evolution on black hole growth, we study a sample of active galactic nuclei (AGN) in galaxies with a calm formation history free of significant mergers, a population that heretofore has been difficult to locate. Here we present an initial sample of 13 AGN in massive (M_* >~ 1e10 M_sun) bulgeless galaxies -- which lack the classical bulges believed inevitably to result from mergers -- selected from the Sloan Digital …
Panchromatic spectral energy distribution (SED) from the ultraviolet (UV), optical to infrared (IR) photometry of NGC 628, combined with the evolutionary stellar population synthesis, is used to derive the spatially resolved age, metallicity and reddening maps. These parameter distributions show that the bulge of this galaxy is a disk-like pseudobulge, which has the S{é}rsic index close to the exponential law, rich gas, and a young circumnuclear ring structure. We also discover the disk has two distinct regions with different radial age and metallicity gradients. The inner region is older and …
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and t…
In this paper, we use the Galaxy Zoo 2 dataset to study the behavior of bars in disk galaxies as a function of specific star formation rate (SSFR), and bulge prominence. Our sample consists of 13,295 disk galaxies, with an overall (strong) bar fraction of $23.6\pm 0.4\%$, of which 1,154 barred galaxies also have bar length measurements. These samples are the largest ever used to study the role of bars in galaxy evolution. We find that the likelihood of a galaxy hosting a bar is anti-correlated with SSFR, regardless of stellar mass or bulge prominence. We find that the trends of bar likelihood …
We review the observed demographics and inferred evolution of supermassive black holes (BHs) found by dynamical modeling of spatially resolved kinematics. Most influential was the discovery of a tight correlation between BH mass and the velocity dispersion of the host-galaxy bulge. It and other correlations led to the belief that BHs and bulges coevolve by regulating each other's growth. New results are now replacing this simple story with a richer and more plausible picture in which BHs correlate differently with different galaxy components. BHs are found in pure-disk galaxies, so classical (…
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…
We consider the luminosity and environmental dependence of structural parameters of lenticular galaxies in the near-infrared K band. Using a two-dimensional galaxy image decomposition technique, we extract bulge and disk structural parameters for a sample of 36 lenticular galaxies observed by us in the K band. By combining data from the literature for field and cluster lenticulars with our data, we study correlations between parameters that characterise the bulge and the disk as a function of luminosity and environment. We find that scaling relations such as the Kormendy relation, photometric …
NGC3367 is a nearby isolated active galaxy that shows a radio jet, a strong bar and evidence of lopsidedness. We present a quantitative analysis of the stellar and gaseous structure of the galaxy disk and a search for evidence of recent interaction based on new UBVRI Halpha and JHK images and on archival Halpha Fabry-Perot and HI VLA data. From a coupled 1D/2D GALFIT bulge/bar/disk decomposition an (B/D ~ 0.07-0.1) exponential pseudobulge is inferred in all the observed bands. A NIR estimate of the bar strength <Q_T{max}(R)> = 0.44 places NGC 3367 bar among the strongest ones. The asymmetry pr…
We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 $μ{\rm m}$ images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk break and using a single disk scale length in the model fit for Type II (down-bending) disk galaxies can lead to differences of 40% in the disk scale length, 10% in bulge-to-total luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios…
We update van den Bergh's parallel sequence galaxy classification in which S0 galaxies form a sequence S0a-S0b-S0c that parallels the sequence Sa-Sb-Sc of spiral galaxies. The ratio B/T of bulge to total light defines the position of a galaxy in each sequence. Our classification makes one improvement. We extend the S0a-S0b-S0c sequence to spheroidal ("Sph'") galaxies that are positioned in parallel to irregular galaxies in a similarly extended Sa-Sb-Sc-Im sequence. This provides a natural "home" for spheroidals, which previously were omitted from galaxy classifications. To motivate our juxtapo…
This is the summary chapter of a review book on galaxy bulges. Bulge properties and formation histories are more varied than those of ellipticals. I emphasize two advances: 1 - "Classical bulges" are observationally indistinguishable from ellipticals, and like them, are thought to form by major galaxy mergers. "Disky pseudobulges" are diskier and more actively star-forming (except in S0s) than are ellipticals. Theys are products of the slow ("secular") evolution of galaxy disks: bars and other nonaxisymmetries move disk gas toward the center, where it starbursts and builds relatively flat, rap…
Boxy and peanut-shaped bulges are seen in about half of edge-on disc galaxies. Comparisons of the photometry and major-axis gas and stellar kinematics of these bulges to simulations of bar formation and evolution indicate that they are bars viewed in projection. If the properties of boxy bulges can be entirely explained by assuming they are bars, then this may imply that their hosts are pure disc galaxies with no classical bulge. A handful of these bulges, including that of the Milky Way, have been observed to rotate cylindrically, i.e. with a mean stellar velocity independent of height above …
Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via available evolution processes. The inner parts shrink and the outer parts expand, provided that some physical process transports energy or angular momentum outward. The evolution of stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks, and galaxy disks are all fundamentally similar. These processes for galaxy disks are the subjects of my lectures and of this Canary Islands Winter School. Part 1 discusses formation, growth, and death of bars. Part 2 details the sl…
The spheroid of the Sombrero galaxy, NGC 4594, is considered a prototype of classical, merger-built bulges. We use a Spitzer, IRAC 3.6 micron image to perform a detailed structural analysis of this galaxy. If one fits to this image only bulge and disc components, the bulge occupies a locus in the mass-size relation close to that of elliptical galaxies. When an outer stellar spheroid is added to improve the fit, the bulge Sersic index drops by a factor of ~ 2, and, if taken at face value, could mean that this bulge is actually a disc-like, pseudo-bulge, or a bar viewed end-on. The bulge effecti…
We present basic predictions of an updated version of the Munich semi-analytic hierarchical galaxy formation model that grows bulges via mergers and disk instabilities. Overall, we find that while spheroids below Ms ~ 10^11 Msun grow their sizes via a mixture of disk instability and mergers, galaxies above it mainly evolve via mergers. Including gas dissipation in major mergers, efficiently shrinks galaxies, especially those with final mass Ms < 10^11 Msun that are the most gas-rich, improving the match with different observables. We find that the predicted scatter in sizes at fixed stellar ma…
We study the relation between the surface density of gas and star formation rate in twenty moderately-inclined, bulgeless disk galaxies (Sd-Sdm Hubble types) using CO(1-0) data from the IRAM 30m telescope, HI emission line data from the VLA/EVLA, H-alpha data from the MDM Observatory, and PAH emission data derived from Spitzer IRAC observations. We specifically investigate the efficiency of star formation as a function of circular velocity (v_circ). Previous work found that the vertical dust structure and disk stability of edge-on, bulgeless disk galaxies transition from diffuse dust lanes wit…
We present a new zoom-in hydrodynamical simulation, "Erisbh", which follows the cosmological evolution and feedback effects of a supermassive black hole at the center of a Milky Way-type galaxy. ErisBH shares the same initial conditions, resolution, recipes of gas cooling, star formation and feedback, as the close Milky Way-analog "Eris", but it also includes prescriptions for the formation, growth and feedback of supermassive black holes. We find that the galaxy's central black hole grows mainly through mergers with other black holes coming from infalling satellite galaxies. The growth by gas…
We present mid-infrared spectra and photometry of thirteen redshift 0.4<z<1 dust-reddened quasars obtained with Spitzer IRS and MIPS. We compare properties derived from their infrared spectral energy distributions (intrinsic AGN luminosity and far-infrared luminosity from star formation) to the host luminosities and morphologies from HST imaging, and black hole masses estimated from optical and/or near-infrared spectroscopy. Our results are broadly consistent with models in which most dust reddened quasars are an intermediate phase between a merger-driven starburst triggering a completely obsc…
We present Spitzer 7-38um spectra for a 24um flux limited sample of galaxies at z~0.7 in the COSMOS field. The detailed high-quality spectra allow us to cleanly separate star formation (SF) and active galactic nucleus (AGN) in individual galaxies. We first decompose mid-infrared Luminosity Functions (LFs). We find that the SF 8um and 15um LFs are well described by Schechter functions. AGNs dominate the space density at high luminosities, which leads to the shallow bright-end slope of the overall mid-infrared LFs. The total infrared (8-1000um) LF from 70um selected galaxies shows a shallower br…
Spitzer Space Telescope Infrared Array Camera (IRAC) imaging provides an opportunity to study all known morphological types of galaxies in the mid-IR at a depth significantly better than ground-based near-infrared and optical images. The goal of this study is to examine the imprint of the de Vaucouleurs classification volume in the 3.6 micron band, which is the best Spitzer waveband for galactic stellar mass morphology owing to its depth and its reddening-free sensitivity mainly to older stars. For this purpose, we have prepared classification images for 207 galaxies from the Spitzer archive, …
We have studied a sample of 101 bright 2MASS galaxies from the Large Galaxy Atlas (LGA), whose morphologies span from early to late-types. We have generated estimates for structural parameters through a two-dimensional (2D) surface brightness photometric decomposition in the three 2MASS bands (J, H, Ks). This work represents a detailed multi-component photometric study of nearby galaxies. We report total magnitudes, effective radii, concentration indices, among other parameters, in the three 2MASS bands. We found that the integrated total magnitudes of early-type galaxies (ETGs) measured on 2M…
We have constructed an extended composite luminosity profile for the Andromeda galaxy, M31, and have decomposed it into three basic luminous structural components: a bulge, a disk and a halo. The dust-free Spitzer/IRAC imaging and extended spatial coverage of ground-based optical imaging and deep star counts allow us to map M31's structure from its center to 22 kpc along the major axis. We apply different decomposition methods for the 1D luminosity profiles and 2D images. These include non-linear least-squares and Bayesian Monte-Carlo Markov-chain analyses. The basic photometric model for M31 …
The Spitzer Survey of Stellar Structure in Galaxies S^4G is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d < 40 Mpc, |b| > 30 degrees, m_(Bcorr) < 15.5, D25>1') survey of 2,331 galaxies using IRAC at 3.6 and 4.5 microns. Each galaxy is observed for 240 s and mapped to > 1.5 x D25. The final mosaicked images have a typical 1 sigma rms noise level of 0.0072 and 0.0093 MJy / sr at 3.6 and 4.5 microns, respectively. Our azimuthally-averaged surface brightness profile typically traces isophotes at mu_3.6 (AB) (…
We present results of Hubble Space Telescope NICMOS H-band imaging of 73 of most luminous (i.e., log[L_IR/L_0]>11.4) Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey (GOALS). This dataset combines multi-wavelength imaging and spectroscopic data from space (Spitzer, HST, GALEX, and Chandra) and ground-based telescopes. In this paper we use the high-resolution near-infrared data to recover nuclear structure that is obscured by dust at optical wavelengths and measure the evolution in this structure along the merger sequence. A large fraction of all galaxies in our sample p…
Accurately weigh the masses of SMBH in AGN is currently possible for only a small group of local and bright broad-line AGN through reverberation mapping (RM). Statistical demographic studies can be carried out considering the empirical scaling relation between the size of the BLR and the AGN optical continuum luminosity. However, there are still biases against low-luminosity or reddened AGN, in which the rest-frame optical radiation can be severely absorbed/diluted by the host and the BLR emission lines could be hard to detect. Our purpose is to widen the applicability of virial-based SE relat…
The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S4G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs (1959) morphology, modified to include recognition of other features such as inner, outer, and n…
