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S. Charlot (IAP/Paris), M. C. Liu, J. R. Graham (UC Berkeley)
We present results from a program studying near-IR surface brightness fluctuations (SBFs) of elliptical galaxies. This work has two aspects. (1) We have measured K-band (2.2~\micron) SBFs of Fornax cluster galaxies to calibrate IR SBFs as a cosmological distance indicator. Unlike many distance indicators, this method is appealing because it has a well-understood physical basis. SBFs in ellipticals are dominated by late-type stars so IR data from 10-m class telescopes can potentially measure distances out to ~~100~h-1~Mpc. Fornax is an ideal cluster for this work because it is compact and has an HST Cepheid-derived distance. (2) We are using optical/IR SBF colors and magnitudes to test the latest stellar population synthesis models. Since SBFs depend on the second moment of the stellar luminosity function, they provide information unobtainable from the first moment alone, i.e. the integrated light. In particular, SBFs are sensitive to the reddest, most luminous stars --- precisely those which are most difficult to model --- and therefore can provide useful new constraints on the unresolved stellar populations in elliptical galaxies.
The author(s) of this abstract have provided an email address for comments about the abstract: charlot@iap.fr