Journal
ASTROPHYSICAL JOURNAL
Volume 782, Issue 2, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/782/2/107
Keywords
cosmology: theory; galaxies: clusters: general; methods: numerical; X-rays: galaxies: clusters
Categories
Funding
- NSF [AST-1009811, OCI-0904484]
- NASA ATP [NNX11AE07G]
- NASA Chandra Theory grant [GO213004B]
- Research Corporation
- Yale Science, Technology and Research Scholars (STARS) Program
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1412768, 1009811] Funding Source: National Science Foundation
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The use of galaxy clusters as cosmological probes hinges on our ability to measure their masses accurately and with high precision. Hydrostatic mass is one of the most common methods for estimating the masses of individual galaxy clusters, which suffer from biases due to departures from hydrostatic equilibrium. Using a large, mass-limited sample of massive galaxy clusters from a high-resolution hydrodynamical cosmological simulation, in this work we show that in addition to turbulent and bulk gas velocities, acceleration of gas introduces biases in the hydrostatic mass estimate of galaxy clusters. In unrelaxed clusters, the acceleration bias is comparable to the bias due to non-thermal pressure associated with merger-induced turbulent and bulk gas motions. In relaxed clusters, the mean mass bias due to acceleration is small (less than or similar to 3%), but the scatter in the mass bias can be reduced by accounting for gas acceleration. Additionally, this acceleration bias is greater in the outskirts of higher redshift clusters where mergers are more frequent and clusters are accreting more rapidly. Since gas acceleration cannot be observed directly, it introduces an irreducible bias for hydrostatic mass estimates. This acceleration bias places limits on how well we can recover cluster masses from future X-ray and microwave observations. We discuss implications for cluster mass estimates based on X-ray, Sunyaev-Zel'dovich effect, and gravitational lensing observations and their impact on cluster cosmology.
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