Stellar populations of classical and pseudo-bulges for a sample of isolated spiral galaxies

In this paper we present the stellar population synthesis results for a sample of 75 bulges in isolated spiral Sb-Sc galaxies, using the spectroscopic data from the Sloan Digital Sky Survey and the STARLIGHT code. We find that both pseudo-bulges and classical bulges in our sample are predominantly composed of old stellar populations, with mean mass-weighted stellar age around 10 Gyr. While the stellar population of pseudo-bulges is, in general, younger than that of classical bulges, the difference is not significant, which indicates that it is hard to distinguish pseudo-bulges from classical bulges, at least for these isolated galaxies, only based on their stellar populations. Pseudo-bulges have star formation activities with relatively longer timescale than classical bulges, indicating that secular evolution is more important in this kind of systems. Our results also show that pseudo-bulges have a lower stellar velocity dispersion than their classical counterparts, which suggests that classical bulges are more dispersion-supported than pseudo-bulges.Comment: 10 pages, 8 figures. Accepted for publication in Astrophysics & Space Scienc

World psychiatric association section of old age psychiatry consensus statement on ethics and capacity in older people with mental disorders

The World Psychiatric Association (WPA) Section of Old Age Psychiatry, since 1997, has developed Consensus Statements relevant to the practice of Old Age Psychiatry. Since 2006 the Section has worked to develop a Consensus Statement on Ethics and Capacity in older people with mental disorders, which was completed in Prague, September 2008, prior to the World Congress in Psychiatry. This Consensus meets one of the goals of the WPA Action Plan 2008–2011, ”to promote the highest ethical standards in psychiatric practice and advocate the rights of persons with mental disorders in all regions of the world“. This Consensus Statement offers to mental health clinicians caring for older people with mental disorders, caregivers, other health professionals and the general public the setting out of and discourse in ethical principles which can often be complex and challenging, supported by practical guidance in meeting such ethical needs and standards, and to encouraged good clinical practice. Copyright © 2009 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64443/1/2279_ftp.pd

Shining Light on Merging Galaxies I: The Ongoing Merger of a Quasar with a `Green Valley' Galaxy

Serendipitous observations of a pair z = 0.37 interacting galaxies (one hosting a quasar) show a massive gaseous bridge of material connecting the two objects. This bridge is photoionized by the quasar (QSO) revealing gas along the entire projected 38 kpc sightline connecting the two galaxies. The emission lines that result give an unprecedented opportunity to study the merger process at this redshift. We determine the kinematics, ionization parameter (log U ~ -2.5 +- 0.03), column density (N_H ~ 10^{21} cm^{-2}), metallicity ([M/H] ~ -0.20 +- 0.15), and mass (~ 10^8 Msun) of the gaseous bridge. We simultaneously constrain properties of the QSO-host (M_DM>8.8x 10^{11} Msun) and its companion galaxy (M_DM>2.1 x 10^{11} Msun; M_star ~ 2 x 10^{10} Msun; stellar burst age=300-800 Myr; SFR~6 Msun/yr; and metallicity 12+log (O/H)= 8.64 +- 0.2). The general properties of this system match the standard paradigm of a galaxy-galaxy merger caught between first and second passage while one of the galaxies hosts an active quasar. The companion galaxy lies in the so-called `green valley', with a stellar population consistent with a recent starburst triggered during the first passage of the merger and has no detectable AGN activity. In addition to providing case-studies of quasars associated with galaxy mergers, quasar/galaxy pairs with QSO-photoionized tidal bridges such as this one offer unique insights into the galaxy properties while also distinguishing an important and inadequately understood phase of galaxy evolution.Comment: 23 pages, 12 figures, 5 tables, Submitted to ApJ, revised to address referee's comment

The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs

The Coma cluster was the target of a HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in 2007, the partially completed survey still covers ~50% of the core high-density region in Coma. Observations were performed for 25 fields that extend over a wide range of cluster-centric radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the south-west region of the cluster. In this paper we present reprocessed images and SExtractor source catalogs for our survey fields, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SExtractor Kron magnitudes based only on the measured source flux and half-light radius. We have performed photometry for ~73,000 unique objects; one-half of our detections are brighter than the 10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight majority of objects (60%) are unresolved or only marginally resolved by ACS. We estimate that Coma members are 5-10% of all source detections, which consist of a large population of unresolved objects (primarily GCs but also UCDs) and a wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The red sequence of Coma member galaxies has a constant slope and dispersion across 9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma Treasury program was made available to the public in 2008 August. The images and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd

A large sample of low surface brightness disc galaxies from the SDSS- II. Metallicities in surface brightness bins

We study the spectroscopic properties of a large sample of Low Surface Brightness galaxies (LSBGs) (with B-band central surface brightness mu0(B)>22 mag arcsec^(-2)) selected from the Sloan Digital Sky Survey Data Release 4 (SDSS-DR4) main galaxy sample. A large sample of disk-dominated High Surface Brightness galaxies (HSBGs, with mu0(B)<22 mag arcsec^(-2)) are also selected for comparison simultaneously. To study them in more details, these sample galaxies are further divided into four subgroups according to mu0(B) (in units of mag arcsec^(-2)): vLSBGs (24.5-22.75),iLSBGs (22.75-22.0), iHSBGs (22.0-21.25), and vHSBGs (<21.25). The diagnostic diagram from spectral emission-line ratios shows that the AGN fractions of all the four subgroups are small (<9%). The 21,032 star-forming galaxies with good quality spectroscopic observations are further selected for studying their dust extinction, strong-line ratios, metallicities and stellar mass-metallicities relations. The vLSBGs have lower extinction values and have less metal-rich and massive galaxies than the other subgroups. The oxygen abundances of our LSBGs are not as low as those of the HII regions in LSBGs studied in literature, which could be because our samples are more luminous, and because of the different metallicity calibrations used. We find a correlation between 12+log(O/H) and mu0(B) for vLSBGs, iLSBGs and iHSBGs but show that this could be a result of correlation between mu0(B) and stellar mass and the well-known mass-metallicity relation. This large sample shows that LSBGs span a wide range in metallicity and stellar mass, and they lie nearly on the stellar mass vs. metallicity and N/O vs. O/H relations of normal galaxies. This suggests that LSBGs and HSBGs have not had dramatically different star formation and chemical enrichment histories.Comment: 14 pages, 11 figures, accepted for publication in MNRA

Does the intermediate-mass black hole in LEDA 87300 (RGG 118) follow the near-quadratic Mbh-Mspheroid relation?

The mass scaling relation between supermassive black holes and their host spheroids has previously been described by a quadratic or steeper relation at low masses (105 &lt; Mbh/Mo ≲ 107). How this extends into the realm of intermediate-mass black holes (102 &lt; Mbh/Mo &lt; 105) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of Mbh = 5 104 Mo residing in a "spheroid" of stellar mass equal to 6.3 108 Mo. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic Mbh-Msph,∗ relation. However, Baldassare et al. modeled the bulge and bar as the single spheroidal component of this galaxy. Here we perform a 3-component bulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times fainter than the published "bulge" luminosity. After correcting for dust, we find that Mbulge = 0.9 108 Mo and Mbulge/Mdisk = 0.04 - which is now in accord with ratios typically found in Scd-Sm galaxies. We go on to discuss slight revisions to the stellar velocity dispersion (40 11 km s-1) and black hole mass () and show that LEDA 87300 remains consistent with the Mbh-σ relation, and also the near-quadratic Mbh-Msph,∗ relation when using the reduced bulge mass. LEDA 87300 therefore offers the first support for the rapid but regulated (near-quadratic) growth of black holes, relative to their host bulge/spheroid, extending into the domain of intermediate-mass black holes

Environments of Nearby Quasars in Sloan Digital Sky Survey

For the first time spectroscopic galaxy redshift surveys are reaching the scales where galaxies can be studied together with the nearest quasars. This gives an opportunity to study the dependence between the activity of a quasar and its environment in a more extensive way than before. We study the spatial distribution of galaxies and groups of galaxies in the environments of low redshift quasars in the Sloan Digital Sky Survey (SDSS). Our aim is to understand how the nearby quasars are embedded in the local and global density field of galaxies and how the environment affects quasar activity. We analyse the environments of nearby quasars using number counts of galaxies. We also study the dependence of group properties to their distance to the nearest quasar. The large scale environments are studied by analysing the locations of quasars in the luminosity density field. Our study of the number counts of galaxies in quasar environments shows an underdensity of bright galaxies at a few Mpc from quasars. Also, the groups of galaxies that have a quasar closer than 2Mpc are poorer and less luminous than in average. Our analysis on the luminosity density field shows that quasars clearly avoid rich superclusters. Nearby quasars seem to be located in outskirts of superclusters or in filaments connecting them. Our results suggest that quasar evolution may be affected by density variations both on supercluster scales and in the local environment.Comment: Accepted to A&

Photometric characterization of a well defined sample of isolated galaxies in the context of the AMIGA project

We perform a detailed photometric analysis (bulge-disk-bar decomposition and Concentration-Asymmetry-Clumpiness - CAS parametrization) for a well defined sample of isolated galaxies, extracted from the Catalog of Isolated Galaxies (Karachentseva 1973) and reevaluated morphologically in the context of the AMIGA project. We focus on Sb-Sc morphological types, as they are the most representative population among the isolated spiral galaxies. Assuming that the bulge Sersic index and/or Bulge/Total luminosity ratios are reasonable diagnostics for pseudo- versus classical bulges, we conclude that the majority of late-type isolated disk galaxies likely host pseudobulges rather than classical bulges. Our parametrization of galactic bulges and disks suggests that the properties of the pseudobulges are strongly connected to those of the disks. This may indicate that pseudobulges are formed through internal processes within the disks (i.e. secular evolution) and that bars may play an important role in their formation. Although the sample under investigation covers a narrow morphological range, a clear separation between Sb and Sbc-Sc types is observed in various measures, e.g. the former are redder, brighter, have larger disks and larger bars, more luminous bulges, are more concentrated, more symmetric and clumpier than the latter. A comparison with samples of spiral galaxies (within the same morphological range) selected without isolation criteria reveals that the isolated galaxies tend to host larger bars, are more symmetric, less concentrated and less clumpy.Comment: accepted for publication in MNRAS - 13 figures, 11 table

Kinematics and Stellar Populations of Low-Luminosity Early-Type Galaxies in the Abell 496 Cluster

The morphology and stellar populations of low-luminosity early-type galaxies in clusters have until now been limited to a few relatively nearby clusters such as Virgo or Fornax. Scenarii for the formation and evolution of dwarf galaxies in clusters are therefore not well constrained. We investigate here the morphology and stellar populations of low-luminosity galaxies in the relaxed cluster Abell 496 (z=0.0330). Deep multiband imaging obtained with the CFHT Megacam allowed us to select a sample of faint galaxies (-18.8<M_B<-15.1 mag). We observed 118 galaxies spectroscopically with the ESO VLT FLAMES/Giraffe spectrograph (R=6300). We present structural analysis and colour maps for the 48 galaxies belonging to the cluster. We fit the spectra of 46 objects with PEGASE.HR synthetic spectra to estimate the ages, metallicities, and velocity dispersions. We computed values of $\alpha$/Fe abundance ratios from the measurements of Lick indices. High-precision estimates of stellar population properties have been obtained for a large sample of faint galaxies in a cluster, allowing for the extension of relations between stellar populations and internal kinematics to the low-velocity dispersion regime. We have revealed a peculiar population of elliptical galaxies in the core of the cluster, resembling massive early-type galaxies by their stellar population properties and velocity dispersions, but having luminosities of about 2 mag fainter. External mechanisms of gas removal (ram pressure stripping and gravitational harassment) are more likely to have occurred than internal mechanisms such as supernova-driven winds. The violent tidal stripping of intermediate-luminosity, early-type galaxies in the cluster core can explain the properties of the peculiar elliptical galaxies surrounding the cD galaxy.Comment: Accepted to A&A, 48 pages, 62 figures, 3 tables. This version contains low-resolution figures. We encourage you to get the full-resolution PDF (16Mb) from http://voplus.obspm.fr/DataCollections/Abell0496