Imprints of mass accretion history on the shape of the intracluster medium and the TX-M relation
Abstract
We use a statistical sample of galaxy clusters from a large cosmological N-body + hydrodynamics simulation to examine the relation between morphology, or shape, of the X-ray emitting intracluster medium (ICM) and the mass accretion history of the galaxy clusters. We find that the mass accretion rate (MAR) of a cluster is correlated with the ellipticity of the ICM. The correlation is largely driven by material accreted in the last ∼4.5 Gyr, indicating a characteristic time-scale for relaxation of cluster gas. Furthermore, we find that the ellipticity of the outer regions (R ∼ R500c) of the ICM is correlated with the overall MAR of clusters, while ellipticity of the inner regions (≲0.5 R500c) is sensitive to recent major mergers with mass ratios of ≥1:3. Finally, we examine the impact of variations in cluster mass accretion history on the X-ray observable-mass scaling relations. We show that there is a continuous anticorrelation between the residuals in the TX-M relation and cluster MARs, within which merging and relaxed clusters occupy extremes of the distribution rather than form two peaks in a bimodal distribution, as was often assumed previously. Our results indicate that the systematic uncertainties in the X-ray observable-mass relations can be mitigated by using the information encoded in the apparent ICM ellipticity.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2019
- DOI:
- 10.1093/mnras/stz2776
- arXiv:
- arXiv:1903.08662
- Bibcode:
- 2019MNRAS.490.2380C
- Keywords:
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- methods: numerical;
- galaxies: clusters: general;
- galaxies: clusters: intracluster medium;
- cosmology: theory;
- X-rays: galaxies: clusters;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 10 pages, 7 figures, comments welcome