EVOLUTION OF THE MERGER-INDUCED HYDROSTATIC MASS BIAS IN GALAXY CLUSTERS

Journal Article · Fri Jun 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/751/2/121· OSTI ID:22037170

Nelson, Kaylea; Nagai, Daisuke ^[1]; Rudd, Douglas H; Shaw, Laurie ^[2]

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1. Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
2. Department of Physics, Yale University, New Haven, CT 06520 (United States)

In this work, we examine the effects of mergers on the hydrostatic mass estimate of galaxy clusters using high-resolution Eulerian cosmological simulations. We utilize merger trees to isolate the last merger for each cluster in our sample and follow the time evolution of the hydrostatic mass bias as the systems relax. We find that during a merger, a shock propagates outward from the parent cluster, resulting in an overestimate in the hydrostatic mass bias. After the merger, as a cluster relaxes, the bias in hydrostatic mass estimate decreases but remains at a level of -5%-10% with 15%-20% scatter within r{sub 500}. We also investigate the post-merger evolution of the pressure support from bulk motions, a dominant cause of this residual mass bias. At r{sub 500}, the contribution from random motions peaks at 30% of the total pressure during the merger and quickly decays to {approx}10%-15% as a cluster relaxes. Additionally, we use a measure of the random motion pressure to correct the hydrostatic mass estimate. We discover that 4 Gyr after mergers, the direct effects of the merger event on the hydrostatic mass bias have become negligible. Thereafter, the mass bias is primarily due to residual bulk motions in the gas which are not accounted for in the hydrostatic equilibrium equation. We present a hydrostatic mass bias correction method that can recover the unbiased cluster mass for relaxed clusters with 9% scatter at r{sub 500} and 11% scatter in the outskirts, within r{sub 200}.

• OSTI ID: 22037170
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 751; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
COMPUTERIZED SIMULATION
CORRECTIONS
COSMOLOGY
EQUILIBRIUM
GALACTIC EVOLUTION
GALAXY CLUSTERS
MASS
RANDOMNESS