{
  "id": "1903.08662",
  "version": "v1",
  "published": "2019-03-20T18:00:02.000Z",
  "updated": "2019-03-20T18:00:02.000Z",
  "title": "Imprints of Mass Accretion History on the Shape of the Intracluster Medium and the $T_X-M$ Relation",
  "authors": [
    "Huanqing Chen",
    "Camille Avestruz",
    "Andrey V. Kravtsov",
    "Erwin T. Lau",
    "Daisuke Nagai"
  ],
  "comment": "10 pages, 7 figures, comments welcome",
  "categories": [
    "astro-ph.GA"
  ],
  "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 $\\sim 4.5$~Gyr, indicating a characteristic time-scale for relaxation of cluster gas. Furthermore, we find that the ellipticity of the outer regions ($R\\sim R_{\\rm 500c}$) of the ICM is correlated with the overall MAR of clusters, while ellipticity of the inner regions ($\\lesssim 0.5 R_{\\rm 500c}$) is sensitive to recent major mergers with mass ratios of $\\geq 1:3$. 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 {\\it continuous\\/} anti-correlation between the residuals in the $T_x-M$ relation and cluster MARs, within which merging and relaxed clusters occupy extremes of the distribution rather than form two peaks in a bi-modal distribution, as was often assumed previously. Our results indicate the systematic uncertainties in the X-ray observable-mass relations can be mitigated by using the information encoded in the apparent ICM ellipticity.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-03-20T18:00:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galaxy clusters",
      "ellipticity",
      "cluster mass accretion history",
      "mass accretion rate",
      "x-ray emitting intracluster medium"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}