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J. Silge, K. Gebhardt (UT Austin)
We have obtained spectra and measured the stellar kinematics in a sample of nearby early-type galaxies using the near infrared CO absorption bandhead at 2.29 microns. Recent observations have shown that galaxies, even ellipticals and the bulges of galaxies, contain an unexpectedly large amount of dust. Modeling motivated by these observations shows that this dust can have a significant effect on the observed kinematics of these galaxies. These results imply that our current kinematic understanding of galaxies, based on optical data, may be flawed in a fundamental way. For example, biased dispersion estimates can distort the Fundamental Plane, thereby altering the physical interpretation. More importantly, the amount of dark matter may also be biased using optical kinematics alone. Using IR wavelengths allows us to look through the dust and observe the older stellar population, gaining a more accurate measure of the dynamics. We compare these results with optical data for these galaxies and examine the systematic effects of optical versus infrared kinematics.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.