Bibcode
Toloba, E.; Guhathakurta, P.; Peletier, R. F.; Boselli, A.; Lisker, T.; Falcón-Barroso, J.; Simon, J. D.; van de Ven, G.; Paudel, S.; Emsellem, E.; Janz, J.; den Brok, M.; Gorgas, J.; Hensler, G.; Laurikainen, E.; Niemi, S.-M.; Ryś, A.; Salo, H.
Bibliographical reference
The Astrophysical Journal Supplement, Volume 215, Issue 2, article id. 17, 51 pp. (2014).
Advertised on:
12
2014
Citations
61
Refereed citations
58
Description
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 < Mr <–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
(Hβ and HγA ) and metallicity sensitive
(Fe4668 and Mgb) Lick spectral indices in the LIS-5 Å 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, the mass-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
Re of log Me = 9.1 ± 0.2 and a median dark
matter fraction within the Re 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.
Related projects
Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro