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arXiv · 1004.0319

The Physical Origins of The Morphology-Density Relation: Evidence for Gas Stripping from the SDSS

Arjen van der Wel·Eric F. Bell·Bradford P. Holden·Ramin A. Skibba·Hans-Walter-Rix
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Abstract

We provide a physical interpretation and explanation of the morphology-density relation for galaxies, drawing on stellar masses, star formation rates, axis ratios and group halo masses from the Sloan Digital Sky Survey. We first re-cast the classical morphology-density relation in more quantitative terms, using low star formation rate (quiescence) as a proxy for early-type morphology and dark matter halo mass from a group catalog as a proxy for environmental density: for galaxies of a given stellar mass the quiescent fraction is found to increase with increasing dark matter halo mass. Our novel result is that - at a given stellar mass - quiescent galaxies are significantly flatter in dense environments, implying a higher fraction of disk galaxies. Supposing that the denser environments differ simply by a higher incidence of quiescent disk galaxies that are structurally similar to star-forming disk galaxies of similar mass, explains simultaneously and quantitatively these quiescence -nvironment and shape-environment relations. Our findings add considerable weight to the slow removal of gas as the main physical driver of the morphology-density relation, at the expense of other explanations.

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Arjen van der Wel, Eric F. Bell, Bradford P. Holden, Ramin A. Skibba, Hans-Walter-Rix. 2010-04-26. The Physical Origins of The Morphology-Density Relation: Evidence for Gas Stripping from the SDSS. https://doi.org/10.1088/0004-637x%2F714%2F2%2F1779

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