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Title:
Effects of Baryon Dissipation on the Dark Matter Virial Scaling Relation
Authors:
Lau, Erwin T.; Nagai, Daisuke; Kravtsov, Andrey V.
Affiliation:
AA(Department of Astronomy and Astrophysics, 5640 South Ellis Avenue, The University of Chicago, Chicago, IL 60637, USA ), AB(Department of Physics, Yale University, New Haven, CT 06520, USA ; Yale Center for Astronomy & Astrophysics, Yale University, New Haven, CT 06520, USA ), AC(Department of Astronomy and Astrophysics, 5640 South Ellis Avenue, The University of Chicago, Chicago, IL 60637, USA ; Kavli Institute for Cosmological Physics and Enrico Fermi Institute, 5640 South Ellis Avenue, The University of Chicago, Chicago, IL 60637, USA)
Publication:
The Astrophysical Journal, Volume 708, Issue 2, pp. 1419-1425 (2010). (ApJ Homepage)
Publication Date:
01/2010
Origin:
IOP
ApJ Keywords:
cosmology: theory, dark matter, galaxies: clusters: general, methods: numerical
DOI:
10.1088/0004-637X/708/2/1419
Bibliographic Code:
2010ApJ...708.1419L

Abstract

We investigate effects of baryon dissipation on the dark matter virial scaling relation between total mass and velocity dispersion and the velocity bias of galaxies in groups and clusters using self-consistent cosmological simulations. We show that the baryon dissipation increases the velocity dispersion of dark matter within the virial radius by ≈5%-10%. The effect is mainly driven by the change in density and gravitational potential in inner regions of cluster, and it is larger in lower mass systems where gas cooling and star formation are more efficient. We also show that the galaxy velocity bias depends on how galaxies are selected. Galaxies selected based on their stellar mass exhibit no velocity bias, while galaxies selected based on their total mass show positive bias of ≈10%, consistent with previous results based on collisionless dark matter only simulations. We further find that observational estimates of galaxy velocity dispersion are unbiased with respect to the velocity dispersion of dark matter, provided galaxies are selected using their stellar masses and their velocity dispersions are computed with more than 20 most massive galaxies. Velocity dispersions estimated with fewer galaxies, on the other hand, can lead to a significant underestimate of dynamical masses. Results presented in this paper should be useful in interpreting high-redshift groups and clusters as well as cosmological constraints derived from upcoming optical cluster surveys.
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