Stellar kinematics and structural properties of virgo cluster dwarf early-type galaxies from the smakced project. II. The survey and a systematic analysis of kinematic anomalies and asymmetries



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Toloba, E. and Guhathakurta, P. and Peletier, R. F. and Boselli, A. and Lisker, T. and Falcón Barroso, J. and Simón, J. D. and van de Ven, G. and Paudel, S. and Emsellem, E. and Janz, J. and den Brok, M. and Gorgas García, Francisco Javier and Hensler, G. and Laurikainen, E. and Niemi, S. M. and Rys, A. and Salo, H. (2014) Stellar kinematics and structural properties of virgo cluster dwarf early-type galaxies from the smakced project. II. The survey and a systematic analysis of kinematic anomalies and asymmetries. Astrophysical journal supplement series, 215 (2). ISSN 0067-0049

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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.

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© 2014. The American Astronomical Society. E.T. thanks Laura Ferrarese for very useful suggestions on ellipse-fitting and Tomer Tal, Guillermo Barro, and Michele Cappellari for very helpful discussions. E.T. and P.G. thank Alice Wu and Ajinkya Nene, students of the 2014 Science Internship Program (SIP) for high school students that takes place every summer at UCSC, for their contribution to this manuscript. The authors thank the anonymous referee for useful suggestions that helped improve the manuscript. E.T. acknowledges the financial support of the Fulbright Program jointly with the Spanish Ministry of Education. P.G. acknowledges the NSF grant AST-1010039. T.L. was supported within the framework of the Excellence Initiative by the German Research Foundation (DFG) through the Heidelberg Graduate School of Fundamental Physics (grant number GSC 129/1). R.F.P., J.F.B., G.v.d.V., E.L., and H.S. acknowledge the DAGAL network from the People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme FP7/2007 2013/ under REA grant agreement number PITN GA-2011-289313. J.J. thanks the ARC for financial support (DP130100388). G.H. acknowledges support by the FWF project P21097-N16. This work has made use of the GOLDMine database (Gavazzi et al. 2003) and the NASA/IPAC Extragalactic Database (NED.26)

Uncontrolled Keywords:Digital sky survey; To-light ratio; Dispersion-supported galaxies; Newton-telescope library; Elliptic galaxies; Internal dynamics; Rotation curves; Star-formation; Dark-matter; Local group
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:28575
Deposited On:02 Mar 2015 12:31
Last Modified:10 Dec 2018 15:05

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