The relation between velocity dispersion and mass in simulated clusters of galaxies: dependence on the tracer and the baryonic physics

By E. Munari, A. Biviano, Stefano Borgani, Giuseppe Murante, D. Fabjan. 2013

171 citations recorded by the source corpus.

[Abridged] We present an analysis of the relation between the masses of cluster- and group-sized halos, extracted from $\Lambda$CDM cosmological N-body and hydrodynamic simulations, and their velocity dispersions, at different redshifts from $z=2$ to $z=0$. The main aim of this analysis is to understand how the implementation of baryonic physics in simulations affects such relation, i.e. to what extent the use of the velocity dispersion as a proxy for cluster mass determination is hampered by the imperfect knowledge of the baryonic physics. In our analysis we use several sets of simulations with different physics implemented. Velocity dispersions are determined using three different tracers, DM particles, subhalos, and galaxies. We confirm that DM particles trace a relation that is fully consistent with the theoretical expectations based on the virial theorem and with previous results presented in the literature. On the other hand, subhalos and galaxies trace steeper relations, and with larger values of the normalization. Such relations imply that galaxies and subhalos have a $\sim10$ per cent velocity bias relative to the DM particles, which can be either positive or negative, depending on halo mass, redshift and physics implemented in the simulation. We explain these differences as due to dynamical processes, namely dynamical friction and tidal disruption, acting on substructures and galaxies, but not on DM particles. These processes appear to be more or less effective, depending on the halo masses and the importance of baryon cooling, and may create a non-trivial dependence of the velocity bias and the $\soneD$--$\Mtwo$ relation on the tracer, the halo mass and its redshift. These results are relevant in view of the application of velocity dispersion as a proxy for cluster masses in ongoing and future large redshift surveys.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/2f7fe3c5fa039571c9f40da80491f2ef840e6983

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Citations in the corpus

COSMOLOGICAL CONSTRAINTS FROM GALAXY CLUSTERS IN THE 2500 SQUARE-DEGREE SPT-SZ SURVEY (2016, background): “…of tens of cluster member galaxies, are also mostly unaffected by complex ICM physics but are expensive observationally and have large scatter (e.g., Evrard et al. 2008; Saro et al. 2013; Sifón et al. 2013; Ruel et al. 2014), as well as uncertain velocity bias (e.g., Munari et al. 2013).”
Ultra-diffuse galaxies outside clusters: clues to their formation and evolution (2016, methodology): “In our plot of M200, the estimation of this quantity comes from two different sources (Sifón et al. 2015; Munari et al. 2013), however, our results remain basically the same (β = 0.87 ± 0.05) if we use the methodology of Munari et al. (2013) for estimating M200 for all the structures.”
CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of the z = 0.44 galaxy cluster MACS J1206.2-0847 (2013, background): “Munari et al. (2013) finds thatβ(r) for massive clusters becomes mildly more radial at higher redshift.”