bluuebunny/crossref_metadata_2025_split huggingface dataset:
GAMA: a new galaxy survey
Authors: Baldry I. , Liske J. , Driver S. P. ,   the GAMA Team
Published: July 2008

AbstractThe case is outlined for a new galaxy survey, including spectroscopy with AAOmega and sub-arcsecond multi-band imaging, that bridges a crucial gap between the SDSS and VVDS surveys. The science focus is to study structure and the relationship between matter and light on kpc-to-Mpc scales. The range of scales probed will enable direct constraints on the Cold Dark Matter model by: (1) measuring the halo mass function down to $10^{12}{\cal M}_{\odot}$ and its evolution to z ~ 0.4; (2) measuring the galaxy stellar mass function to very low mass limits of $10^{7}{\cal M}_{\odot}$ constraining baryonic feedback processes; and (3) quantifying the environment-dependent merger rate since z ~ 0.4. Here, we highlight the fact that the high-resolution imaging will enable the bulge-disk decomposition of ~200000 galaxies in u–K, providing a valuable resource for statistical studies of bulge properties.
Tidal interactions and mergers in compact groups
Authors: Plauchu–Frayn I. , Coziol R. 
Published: July 2008

AbstractBased on a NIR morphological study of 25 galaxies in eight Compact Groups (CGs), we find that the galaxies are not in equilibrium but in a process of transformation: late-type galaxies morphological change into earlier types. As much as half of the galaxies in our sample show evidence of ongoing or past mergers.We identify tidal stripping and mergers as the process responsible of this transformation. Our observations also suggest that galaxies in CGs merge more frequently under “dry” conditions (i.e. once they have lost most of their gas).
Boxy/peanut and discy bulges: formation, evolution and properties
Authors: Athanassoula E. 
Published: July 2008

AbstractThe class ‘bulges’ contains objects with very different formation and evolution paths and very different properties. I review two types of ‘bulges’, the boxy/peanut bulges (B/Ps) and the discy bulges. The former are parts of bars seen edge-on, have their origin in vertical instabilities of the disc and are somewhat shorter in extent than bars. Their stellar population is similar to that of the inner part of the disc from which they formed. Discy bulges have a disc-like outline, i.e., seen face-on they are circular or oval and seen edge-on they are thin. Their extent is of the order of 5 times smaller than that of the boxy/peanut bulges. They form from the inflow of mainly gaseous material to the centre of the galaxy and from subsequent star formation. They thus contain a lot of young stars and gas. Bulges of different types often coexist in the same galaxy. I review the main known results on these two types of bulges and present new simulation results.B/Ps form about 1Gyr after the bar, via a vertical buckling. At that time the bar strength decreases, its inner part becomes thicker – forming the peanut or boxy shape – and the ratio $\sigma_z^2/\sigma_r^2$ increases. A second buckling episode is seen in simulations with strong bars, also accompanied by a thickening of the peanut and a weakening of the bar. The properties of the B/Ps correlate strongly with those of the bar: stronger bars have stronger peanuts, a more flat-topped vertical density distribution and have experienced more bucklings.I also present simulations of disc galaxy formation, which include the formation of a discy bulge. Decomposition of their radial density profile into an exponential disc and a Sérsic bulge gives realistic values for the disc and bulge scale-lengths and mass ratios, and a Sérsic shape index of the order of 1.It is thus clear that classical bulges, B/P bulges and discy bulges are three distinct classes of objects and that lumping them together can lead to confusion. To avoid this, the two latter could be called B/P features and inner discs, respectively.
Boxy/peanut bulges, vertical buckling and galactic bars
Authors: Martinez-Valpuesta Inma , Athanassoula E. 
Published: July 2008

AbstractBoxy/peanut bulges in disk galaxies have been associated to stellar bars. In this talk, we discuss the different properties of such bulges and their relation with the corresponding bar, using a very large sample of a few hundred numerical N-body simulations. We present and inter-compare various methods of measuring the boxy/peanut bulge properties, namely its strength, shape and possible asymmetry. Some of these methods can be applied to both simulations and observations. Our final goal is to get correlations that will allow us to obtain information on the boxy/peanut bulge for a galaxy viewed face-on as well as information on the bars of galaxies viewed edge-on.
Internal secular evolution in disk galaxies: the growth of pseudobulges
Authors: Kormendy John 
Published: July 2008

AbstractObservational and theoretical evidence that internal, slow (“secular”) evolution reshapes galaxy disks is reviewed in Kormendy & Kennicutt (2004). This update has three aims. First, I emphasize that this evolution is very general – it is as fundamental to the evolution of galaxy disks as (e. g.) core collapse is to globular clusters, as the production of hot Jupiters is to the evolution of protoplanetary disks, and as evolution to red giants containing proto-white-dwarfs is to stellar evolution. One consequence for disk galaxies is the buildup of dense central components that get mistaken for classical (i. e., merger-built) bulges but that were grown out of disk stars and gas. We call these pseudobulges. Second, I review new results on pseudobulge star formation and structure and on the distinction between boxy and disky pseudobulges. Finally, I highlight how these results make a galaxy formation problem more acute. How can hierarchical clustering produce so many pure disk galaxies with no evidence for merger-built bulges?
The coexistence of classical bulges and disky pseudobulges in early-type disk galaxies
Authors: Erwin Peter 
Published: July 2008

AbstractClose examination of “pseudobulges” in several early-type disk galaxies indicates that they are actually composite structures consisting of both a flattened, kinematically cool disklike structure (“disky pseudobulge”) and a rounder, kinematically hot spheroidal structure (“classical bulge”). This indicates that pseudobulges, thought to form from internal secular evolution, and classical bulges, thought to form from rapid mergers, are not exclusive phenomena: some galaxies can have both.
The structural parameters of bulges, bars and discs in the local Universe
Authors: Gadotti Dimitri Alexei 
Published: July 2008

AbstractImage decomposition of galaxies is now routinely used to estimate the structural parameters of galactic components. In this work, I address questions on the reliability of this technique. In particular, do bars and AGN need to be taken into account to obtain the structural parameters of bulges and discs? And to what extent can we trust image decomposition when the physical spatial resolution is relatively poor? With this aim, I performed multi-component (bar/bulge/disc/AGN) image decomposition of a sample of very nearby galaxies and their artificially redshifted images, and verified the effects of removing the bar and AGN components from the models. Neglecting bars can result in a overestimation of the bulge-to-total luminosity ratio of a factor of two, even if the resolution is low. Similar effects result when bright AGN are not considered in the models, but only when the resolution is high. I also show that the structural parameters of more distant galaxies can in general be reliably retrieved, at least up to the point where the physical spatial resolution is ≈ 1.5 Kpc, but bulge parameters are prone to errors if its effective radius is small compared to the seeing radius, and might suffer from systematic effects. I briefly discuss the consequences of these results to our knowledge of the stellar mass budget in the local universe, and finish by showing preliminary results from a large SDSS sample on the dichotomy between classical and pseudo-bulges.
Vertical surface brightness profiles of boxy bulges
Authors: Aronica G. , Bureau M. , Athanassoula E. , Dettmar R. -J. 
Published: July 2008

AbstractThe thickening of the bar in barred disk galaxies has a strong influence in shaping the morphology in the inner regions of a disk galaxy above the galactic plane. The result of such a secular evolutionary process can be observed in galaxies with box/peanut shaped (b/ps) bulges. We have applied a one–dimensional fitting method to our sample of 30 edge–on disk galaxies using different fitting function approaches. A clear increase in scale height can be observed in the area of the most prominent b/ps isophotes compared to the neighbouring disk and bulge areas, in agreement with the predictions of the bar thickening model.
Strong magnetic spiral pattern in a ringed galaxy NGC 4736
Authors: Chyży Krzysztof T. , Buta Ronald 
Published: July 2008

AbstractWe present high sensitivity radio polarimetric (VLA) observations of a galaxy with strong orbital resonances – NGC 4736. The total radio intensity at 8.4 GHz covers smoothly the whole galaxy bulge and reveals a distinct ring of radio emission closely related to the ring morphology visible in infrared, CO and Hα emission. However, the magnetic field reveals a very coherent spiral pattern. The magnetic field vectors are crossing the inner starbursting ring, the dust lanes within the ring and other rather circularly shaped features visible in other gas traces. Either the magnetic field uncovers the pattern of gas motions not seen in other spectral ranges, or the spiral magnetic field is of a pure dynamo origin, ignoring the ringed morphology of the galaxy.
Lenticular galaxies in the process of evolution
Authors: Kemp S. N. , Grana J. A. Pérez , Meaburn J. , de la Fuente Eduardo 
Published: July 2008

AbstractWe present images of a number of lenticular galaxies which appear to be undergoing evolutionary processes such as ram-pressure stripping or gravitational interactions, or possess features indicative of some evolutionary process in the recent past, such as fossil spiral arms, a polar ring-like structure, or a warped disk with box-peanut bulge. All the galaxies were originally identified on digitally co-added photographic plates or films from the UK Schmidt Telescope, showing that such material is still useful in spite of the modern digital surveys available. In some cases CCD follow up is presented.
The formation of young B/PS bulges in edge-on barred galaxies
Authors: Wozniak H. , Michel-Dansac L. 
Published: July 2008

AbstractWe report about the fact that the stellar population that is born in the gas inflowing towards the central regions can be vertically unstable leading to a B/PS feature remarkably bluer that the surrounding bulge. Using new chemodynamical simulations we show that this young population does not remain as flat as the gaseous nuclear disc and buckles out of the plane to form a new boxy bulge. We show that such a young B/PS bulge can be detected in colour maps.
Fueling-controlled growth of massive black holes
Authors: Escala Andrés 
Published: July 2008

AbstractWe study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using AMR numerical simulations, we analyze how gas is transported into the nuclear (central kpc) regions of galaxies. We study gas fueling onto the inner accretion disk (sub-pc scale) and star formation in a massive nuclear disk like those generally found in proto-spheroids (ULIRGs, SCUBA Galaxies). These sub-pc resolution simulations of gas fueling, which is mainly depleted by star formation, naturally satisfy the ‘MBH- Mvirial’ relation, with a scatter considerably less than that observed. We find that a generalized version of the Kennicutt-Schmidt Law for starbursts is satisfied, in which the total gas depletion rate (Ṁgas= ṀBH+ ṀSF) scales as Mgas/torbital.
Building up mass in the centers of late type galaxies
Authors: Schinnerer E. , Böker T. , Emsellem E. , Lisenfeld U. , Downes D. 
Published: July 2008

AbstractWe present highest angular resolution (~ 1″ and 0.35″) mm-interferometric observations of the HCN(1-0), 12CO(1-0) and 12CO(2-1) line emission in the central 300 pc of the late-type spiral galaxy NGC 6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI) shows for the first time a molecular gas spiral in the inner ~ 10″ (270 pc) with a large concentration of molecular gas ($M_{H_2} \sim\,1.6\times10^7\,M_{\odot}$) within the inner 60 pc, The gas distribution in the central 50 pc has been resolved and is consistent with a gas ring or spiral driven by a bar. Both the distribution of the molecular gas as well as its kinematics can be well explained by the influence of an inner stellar bar of about 400 pc length as tested via a qualitative model for the gas flow. NGC 6946 is a prime example of molecular gas kinematics being driven by a small-scale, secondary stellar bar.For the first time, it is possible to directly compare the location of (dense) giant molecular clouds with that of (optically) visible HII regions in space-based images. We use the 3 mm continuum and the HCN emission to estimate in the central 50 pc the star formation rates in young clusters that are still embedded in their parent clouds and hence are missed in optical and near-IR surveys of star formation. The amount of embedded star formation is about 1.6 times as high as that measured from HII regions alone, and appears roughly evenly split between ongoing dust-obscured star formation and very young giant molecular cloud cores that are just beginning to form stars. The build-up of central mass seems to have continued over the past ≥ 10 Myrs, to have occurred in an extended (albeit small) volume around the nucleus, and to be closely related to the presence of an inner bar.
Disk growth in bulge-dominated galaxies: molecular gas and morphological evolution
Authors: Young Lisa , Bureau Martin , Crocker Alison , Combes Francoise 
Published: July 2008

AbstractSubstantial numbers of morphologically regular early-type (elliptical and lenticular) galaxies contain molecular gas, and the quantities of gas are probably sufficient to explain recent estimates of the current level of star formation activity. This gas can also be used as a tracer of the processes that drive the evolution of early-type galaxies. For example, in most cases the gas is forming dynamically cold stellar disks with sizes in the range of hundreds of pc to more than one kpc, although there is typically only 1% of the total stellar mass currently available to form young stars. The numbers are still small, but the molecular kinematics indicate that some of the gas probably originated from internal stellar mass loss while some was acquired from outside. Future studies will help to quantify the role of molecular gas (dissipational processes) in the formation of early-type galaxies and their evolution along the red sequence.
A SINFONI view of circum-nuclear star-forming rings in spiral galaxies
Authors: Falcón-Barroso Jesús , Böker Torsten , Schinnerer Eva , Knapen Johan H. , Ryder Stuart 
Published: July 2008

AbstractWe present near-infrared (H- and K-band) SINFONI integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. We made use of the relative intensities of different emission lines (i.e. [FeII], HeI, Brγ) to age date the stellar clusters present along the rings. This qualitative, yet robust, method allows us to discriminate between two distinct scenarios that describe how star formation progresses along the rings. Our findings favour a model where star formation is triggered predominantly at the intersection between the bar major axis and the inner Lindblad resonance and then passively evolves as the clusters rotate around the ring (‘Pearls on a string’ scenario), although models of stochastically distributed star formation (‘Popcorn’ model) cannot be completely ruled out.
LINER-like emission in red galaxies: evolutionary phase or recurring phenomenon?
Authors: Graves Genevieve J. 
Published: July 2008

AbstractWe present recent results showing that a large fraction of red sequence galaxies contain ionized gas with LINER-like optical emission line ratios. This emission is more frequently found in galaxies with lower central velocity dispersion (σ) and these galaxies typically have younger mean ages than galaxies at the same σ which do not host emission. We suggest that the presence of LINER-like emission may be determined by the quantity of interstellar material in these galaxies and may be associated with the recent accretion of a gas-rich satellite galaxy or alternatively with stellar mass loss that declines as the galaxy stellar population ages.
Why are some brightest cluster galaxies forming stars?
Authors: O'Dea Christopher P. , Quillen Alice , Zufelt Nicholas , Park Jaehong , Edge Alastair , Russell Helen , Fabian Andy , Baum Stefi ,   The Spitzer BCG Project
Published: July 2008

AbstractWe present first results from an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission located in the cores of X-ray luminous clusters selected from the ROSAT All-Sky Survey. We find that 1/3 of these sources have signs of excess infrared emission; 22 objects of 62 are detected at 70 μm and 19 have 8 to 5.8 μm flux ratios above 0.98. The strength of the excess emission correlates with the luminosity of the optical emission lines. Excluding the four systems dominated by an AGN, the excess mid-infrared emission in the remaining brightest cluster galaxies is likely powered by star formation. We find a correlation between mass deposition rate from a cooling flow model for the X-ray emission and the star formation rate estimated from the infrared luminosity. The star formation rates are 1/10 to 1/100 of the mass deposition rates expected in the absence of heating suggesting that the re-heating of the ICM is generally very effective in reducing the amount of mass cooling from the hot phase.
Star formation in the Galactic bulge: the role of collisions
Authors: Cropper Mark , Putte Dave Vande 
Published: July 2008

AbstractPrompted by the possibility that we have observed star formation triggered by globular cluster and dwarf spheroidal transits through galactic disks, we have examined kinematic evidence as to whether the superstar clusters in the Galactic bulge could have been formed from such transits. From their trajectores, we cannot exclude such a possibility. We note also that the high frequency of these transits may have generated rapid star formation at early times, and that remnant cluster cores may themselves nucleate further star formation.
Recent star formation in high-redshift early-type galaxies: insights from the rest-frame UV
Authors: Kaviraj S. , Yi S. K. , Gawiser E. , van Dokkum P. G. , Khochfar S. , Schawinski K. , Silk J. 
Published: July 2008

AbstractWe combine deep UBV RIzJK photometry from the MUSYC survey with redshifts from the COMBO-17 survey to study the rest-frame ultraviolet (UV) properties of 674 high-redshift (0.5 < z < 1) early-type galaxies, drawn from the Extended Chandra Deep Field South (E-CDFS). Galaxy morphologies are determined through visual inspection of Hubble Space Telescope (HST) images taken from the GEMS survey. We harness the sensitivity of the UV to young (<1 Gyrs old) stars to quantify the recent star formation history of the early-type population. We find compelling evidence that early-types of all luminosities form stars over the lifetime of the Universe, although the bulk of their star formation is already complete at high redshift. Luminous (−23 < M(V) < −20.5) early-types form 10-15 percent of their mass after z = 1, while their less luminous (M(V) > −20.5) counterparts form 30-60 percent of their mass in the same redshift range.
A black hole fundamental plane
Authors: Hopkins Philip F. 
Published: July 2008

AbstractWe study observed correlations between supermassive black hole (BHs) and the properties of their host galaxies, and show that the observations define a BH “fundamental plane” (BHFP), of the form $\mbh\propto\sigma^{3.0\pm0.3}\,\re^{0.43\pm0.19}$ or $\mbh\propto\mstar^{0.54\pm0.17}\,\sigma^{2.2\pm0.5}$, analogous to the FP of elliptical galaxies. The BHFP is preferred over a simple relation between MBH and any of σ, M*, Mdyn, or Re alone at > 3 σ (99.9%) significance. The existence of this BHFP has important implications for the formation of supermassive BHs and the masses of the very largest black holes, and immediately resolves several apparent conflicts between the BH masses expected and measured for outliers in both the MBH − σ and MBH − M* relations.
Co-evolution of bulges and black holes
Authors: Woo Jong-Hak , Treu Tommaso , Malkan Matthew A. , Blandford Roger D. 
Published: July 2008

AbstractIn the present-day universe, the global properties of bulges and early-type galaxies correlate with the mass of their central black holes, indicating a connection between galaxy evolution and nuclear activity. Understanding the origin of this relation is a major challenge for cosmological models. Using Keck spectra and HST images, we present direct measurements of the correlations between black hole mass and host spheroid luminosity and velocity dispersion at z=0.36, showing that the relations evolved significantly in the past 4 billion years. It appears that black holes of a few 108M⊙completed their growth before their host galaxies, and that the current scaling relations are only the final point of the co-evolution of galaxies and black holes.
The Vc − σ0 relation of galaxies
Authors: Courteau Stéphane , McDonald Michael , Widrow Lawrence M. 
Published: July 2008

AbstractCourteau et al. (2007a) reported on the dependence of the ratio of a galaxy's maximum circular velocity, Vc, to its central velocity dispersion, σ0, on morphology, or equivalently total light concentration. This Vc − σ0–concentration relation, which involves details about the local and global galaxy physics, poses a fundamental challenge for galaxy structure models. Furthermore, not only must these models reproduce the Vc − σ0 relation and its various dependences, they must simultaneously match other fundamental scaling relations such as the velocity-size-luminosity and color-luminosity relations. We focus here on the interpretation of parameters that enter the Vc − σ0 relation to enable proper data-model comparisons and follow-up studies by galaxy modelers and observers.
Searching for mergers in early-type QSO host galaxies and a control sample of inactive ellipticals
Authors: Bennert Nicola , Canalizo Gabriela , Jungwiert Bruno , Stockton Alan , Schweizer François , Peng Chien , Lacy Mark 
Published: July 2008

AbstractWe present very deep HST/ACS images of five QSO host galaxies, classified as undisturbed ellipticals in earlier studies. For four of the five objects, our images reveal strong signs of interaction such as tidal tails, shells, and other fine structure, suggesting that a large fraction of QSO host galaxies may have experienced a relatively recent merger event. Our preliminary results for a control sample of inactive elliptical galaxies do not reveal comparable fine structure.
The spectral decomposition of Active Galactic Nuclei with double-peaked Balmer lines from SDSS
Authors: Bian W. 
Published: July 2008

AbstractFor a sample of 52 double-peaked broad-lines AGNs from the Sloan Digital Sky Survey (SDSS), we do the spectral decomposition to obtain the host spectrum and the nuclei spectrum from their SDSS spectra, as well as the bulge luminosity (Lbulge), stellar velocity dispersion (σ*). A strong correlation is found between the σ* and the gaseous velocity dispersion in narrow line regions. With the Mbh − σ* relation, we estimate the black hole masses, range from 1.0 × 107 to 6 × 108 M⊙, and the Eddington ratio from about 0.01 to about 1. It is consistent with the result from Mbh − Lbulge relation. However, it is not consistent with the mass from the Hβ FWHM. It seems that the empirical size-luminosity relation for broad line regions dose not hold for double-peaked AGNs, otherwise the calibration factor is as small as 0.185, suggesting the non-virial dynamics of broad line regions.