A survey of merger remnants. II. The emerging kinematic and photometric correlations

This paper is the second in a series exploring the properties of 51 optically selected, single-nuclei merger remnants. Spectroscopic data have been obtained for a subsample of 38 mergers and combined with previously obtained infrared photometry to test whether mergers exhibit the same correlations as elliptical galaxies among parameters such as stellar luminosity and distribution, central stellar velocity dispersion (sigma(0)), and metallicity. Paramount to the study is to test whether mergers lie on the fundamental plane. Measurements of sigma(0) have been made using the Ca triplet absorption line at 8500 angstrom for all 38 mergers in the subsample. Additional measurements of sigma(0) were made for two of the mergers in the subsample using the CO absorption line at 2.29 mu m. The results indicate that mergers show a strong correlation among the parameters of the fundamental plane but fail to show a strong correlation between sigma(0) and metallicity (Mg-2). In contrast to earlier studies, the sigma(0) values of the mergers are consistent with objects that lie somewhere between intermediate-mass and luminous giant elliptical galaxies. However, the discrepancies with earlier studies appear to correlate with whether the Ca triplet or CO absorption lines are used to derive sigma(0), with the latter almost always producing smaller values. Finally, the photometric and kinematic data are used to demonstrate for the first time that the central phase-space densities of mergers are equivalent to those in elliptical galaxies. This resolves a long-standing criticism of the merger hypothesis.