Stellar populations of kinematically decoupled cores in E/S0 galaxies

Richard M. McDermid*, Eric Emsellem, Kristen L. Shapiro, Roland Bacon, Martin Bureau, Michele Cappellari, Roger L. Davies, Tim De Zeeuw, Jesús Falcón-Barroso, Davor Krajnovíc, Harald Kuntschner, Reynier F. Peletier, Marc Sarzi

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

In this poster contribution, we present results from high spatial resolution integral-field spectroscopy of elliptical (E) and lenticular (S0) galaxies from the SAURON representative survey, obtained with the OASIS and GMOS spectrographs. These seeing-limited observations explore the central 10'10 (typically one kiloparsec diameter) regions of these galaxies using a spatial sampling four times higher than SAURON (027 vs. 094 spatial elements), resulting in almost a factor of two improvement in the median PSF. These data allow accurate study of the central regions to complement the large-scale view provided by SAURON. We derive the stellar and gas kinematics, stellar absorption-line strengths and nebular emission-line strengths for our sample, and derive maps of the luminosity-weighted stellar age, metallicity and abundance ratio via stellar population models. From these data we find a wealth of structures either not seen or poorly resolved in the SAURON data, including a number of kinematically-decoupled cores (KDCs) in the centres of some galaxies. We compare the intrinsic size and luminosity-weighted stellar age of all the visible KDCs in the full SAURON sample, and find two types of components: kiloparsec-scale KDCs, which are older than 8 Gyr, and are found in galaxies with little net rotation; and compact KDCs, which have intrinsic diameters of less than a few hundred parsec, show a range of stellar ages from 0.5 - 15 Gyr (with 5/6 younger than 5 Gyr), are found exclusively in fast-rotating galaxies, and are close to counter-rotating around the same axis as their host. Of the 7 galaxies in the SAURON sample with integrated luminosity-weighted ages less than 5 Gyr, 5 show such compact KDCs, suggesting a link between counter-rotation and recent star-formation. We show that this may be partly due to a combination of small sample size at young ages, and an observational bias, since young KDCs are easier to detect than their older and/or co-rot ating counterparts.

Original languageEnglish
Pages (from-to)122
Number of pages1
JournalProceedings of the International Astronomical Union
Volume2
Issue numberS235
DOIs
Publication statusPublished - Aug 2006
Externally publishedYes

Keywords

  • CD
  • Evolution
  • Formation
  • Galaxies: elliptical and lenticular
  • Kinematics and dynamics
  • Stellar content
  • Structure

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