Near-Infrared Synthetic Spectra of Elliptical Galaxies

Abstract

We present the first results from our population synthesis models of elliptical galaxies. In this paper, we concentrate upon the near-infrared region of the spectrum (0.7-3 um). We model elliptical galaxies as coeval, single-metallicity stellar populations. Integrated spectra are constructed from synthetic spectra of the stars which lie along 6, 10 and 16 Gyr isochrones having [Fe/H]=+0.39, 0.00 and -0.47. The V-K and H-K colors and CO indices measured from our synthetic, integrated spectra are found to agree well with E/S0 galaxy photometry, but the J-K colors of the models are redder than the galaxies at a given V-K. We attribute this discrepancy to the oscillator strengths we employ for spectral lines in the phi system of TiO. We have probably overestimated the strengths of these lines, causing our J-band magnitudes to be too faint and our model J-K colors too red.