Journal Article

Optical and near-infrared velocity dispersions of early-type galaxies*

Joachim Vanderbeke, Maarten Baes, Aaron J. Romanowsky and Linda Schmidtobreick

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 412, issue 3, pages 2017-2025
Published in print April 2011 | ISSN: 0035-8711
Published online April 2011 | e-ISSN: 1365-2966 | DOI:
Optical and near-infrared velocity dispersions of early-type galaxies*

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We have carried out a systematic, homogeneous comparison of optical and near-infrared dispersions. Our magnitude-limited sample of early-type galaxies (ETGs) in the Fornax cluster comprises 11 elliptical and 11 lenticular galaxies more luminous than MB=−17. We were able to determine the central dispersions based on the near-infrared CO absorption band head for 19 of those galaxies. The velocity dispersions range from less than 70 km s−1 to over 400 km s−1. We compare our near-infrared velocity dispersions to the optical dispersions measured by Kuntschner. Contrary to previous studies, we find a one-to-one correspondence with a median fractional difference of 6.4 per cent. We examine the correlation between the relative dust mass and the fractional difference of the velocity dispersions, but find no significant trend. Our results suggest that early-type galaxies are largely optically thin, which is consistent with recent Herschel observations.

Keywords: galaxies: clusters: individual: Fornax; galaxies: elliptical and lenticular, cD; galaxies: kinematics and dynamics

Journal Article.  6128 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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