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arXiv · 1704.07843

The Velocity Dispersion Function for Quiescent Galaxies in the Local Universe

Jubee Sohn·H. Jabran Zahid·Margaret J. Geller
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Abstract

We investigate the distribution of central velocity dispersions for quiescent galaxies in the SDSS at $0.03 \leq z \leq 0.10$. To construct the field velocity dispersion function (VDF), we construct a velocity dispersion complete sample of quiescent galaxies with Dn4000$ > 1.5$. The sample consists of galaxies with central velocity dispersion larger than the velocity dispersion completeness limit of the SDSS survey. Our VDF measurement is consistent with previous field VDFs for $σ> 200$ km s$^{-1}$. In contrast with previous results, the VDF does not decline significantly for $σ< 200$ km s$^{-1}$. The field and the similarly constructed cluster VDFs are remarkably flat at low velocity dispersion ($σ< 250$ km s$^{-1}$). The cluster VDF exceeds the field for $σ> 250$ km s$^{-1}$ providing a measure of the relatively larger number of massive subhalos in clusters. The VDF is a probe of the dark matter halo distribution because the measured central velocity dispersion may be directly proportional to the dark matter velocity dispersion. Thus the VDF provides a potentially powerful test of simulations for models of structure formation.

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Jubee Sohn, H. Jabran Zahid, Margaret J. Geller. 2017-07-03. The Velocity Dispersion Function for Quiescent Galaxies in the Local Universe. https://doi.org/10.3847/1538-4357%2Faa7de3

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