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Ultraviolet color-magnitude relation of early-type dwarf galaxies in the Virgo cluster
Kim, S.,Rey, S.-C.,Lisker, T. WILEY-VCH Verlag 2009 Astronomische Nachrichten Vol.330 No.9
<P>We present ultraviolet (UV) color-magnitude relations (CMRs) for dwarf ellipticals (dEs) and dwarf lenticulars (dS0s) in the Virgo cluster. We used the Galaxy Evolution Explorer (GALEX) GR3 photometric data in far-ultraviolet (FUV) and near-ultraviolet (NUV) passbands combined with SDSS DR5 data. We found that dS0s as well as peculiar dEs (dEs with blue center and disk) found by Lisker et al. (2006a, b) show distinct locus from that of ordinary dEs in UV CMRs. The dS0s and peculiar dEs have bluer UV colors than ordinary dEs at a fixed optical luminosity. Furthermore, UV colors of dEs in outer region of the cluster are systematically bluer than those in inner region. Since UV flux is sensitive to the presence of young stellar population from recent star formation activity, our results suggest that there are different star formation histories among different subsample of early-type dwarf galaxies in Virgo cluster concerning their morphology and environmental effect (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
THE EXTENDED VIRGO CLUSTER CATALOG
Kim, Suk,Rey, Soo-Chang,Jerjen, Helmut,Lisker, Thorsten,Sung, Eon-Chang,Lee, Youngdae,Chung, Jiwon,Pak, Mina,Yi, Wonhyeong,Lee, Woong IOP Publishing 2014 The Astrophysical journal Supplement series Vol.215 No.2
<P>We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg(2) or 60.1 Mpc(2). It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s(-1). In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.</P>
Toloba, E.,Guhathakurta, P.,Peletier, R. F.,Boselli, A.,Lisker, T.,Falcó,n-Barroso, J.,Simon, J. D.,van de Ven, G.,Paudel, S.,Emsellem, E.,Janz, J.,den Brok, M.,Gorgas, J.,Hensler, G.,Laurikaine IOP Publishing 2014 The Astrophysical journal Supplement series Vol.215 No.2
<P>We present spatially resolved kinematics and global stellar populations and mass-to-light ratios for a sample of 39 dwarf early-type (dE) galaxies in the Virgo cluster studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. This sample is representative of the early-type population in the Virgo cluster in the absolute magnitude range -19.0 < M-r < -16.0 and of all morphological subclasses found in this galaxy population. For each dE, we measure the rotation curve and velocity dispersion profile and fit an analytic function to the rotation curve. We study the significance of the departure of the rotation curve from the best-fit analytic function (poorly fit) and of the difference between the approaching and receding sides of the rotation curve (asymmetry). Our sample includes two dEs with kinematically decoupled cores that have been previously reported. We find that 62 +/- 8% (23 out of the 39) of the dEs have a significant anomaly in their rotation curve. Analysis of the images reveals photometric anomalies for most galaxies. However, there is no clear correlation between the significance of the photometric and kinematic anomalies. We measure age-sensitive (H-beta and H-gamma A) and metallicity sensitive (Fe4668 and Mgb) Lick spectral indices in the LIS-5 angstrom system. This population of galaxies exhibits a wide range of ages and metallicities; we also find that 4 dEs show clear evidence of emission partially filling in the Balmer absorption lines. Finally, we estimate the total masses and dark matter fractions of the dEs and plot them in the mass-size, themass-velocity dispersion, and the fundamental plane scaling relations. The dEs seem to be the bridge between massive early-type galaxies and dSphs, and have a median total mass within the R-e of logM(e) = 9.1 +/- 0.2 and a median dark matter fraction within the R-e of f(DM) = 46 +/- 18%. Any formation model for the dE galaxy class must account for this diversity of kinematic and photometric anomalies and stellar populations.</P>