{
  "id": "1410.2891",
  "version": "v1",
  "published": "2014-10-10T20:00:01.000Z",
  "updated": "2014-10-10T20:00:01.000Z",
  "title": "The rise and fall of star-formation in $\\bf z\\sim0.2$ merging galaxy clusters",
  "authors": [
    "Andra Stroe",
    "David Sobral",
    "William Dawson",
    "M. James Jee",
    "Henk Hoekstra",
    "David Wittman",
    "Reinout J. van Weeren",
    "Marcus Brüggen",
    "Huub J. A. Röttgering"
  ],
  "comment": "Submitted for publication in MNRAS. Comments welcome. 20 pages, 15 figures, 5 tables",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "CIZA J2242.8+5301 (`Sausage') and 1RXS J0603.3+4213 (`Toothbrush') are two low-redshift ($z\\sim0.2$), massive ($\\sim2\\times10^{15}M_\\odot$), post-core passage merging clusters, which host shock waves traced by diffuse radio emission. To study their star-formation properties, we uniformly survey the `Sausage' and `Toothbrush' clusters in broad and narrow band filters and select a sample of $201$ and $463$ line emitters, down to a rest-frame equivalent width ($13${\\AA}). We robustly separate between H$\\alpha$ and higher redshift emitters using a combination of optical multi-band (B, g, V, r, i, z) and spectroscopic data. We build H$\\alpha$ luminosity functions for the entire cluster region, near the shock fronts, and away from the shock fronts and find striking differences between the two clusters. In the dynamically younger, $1$ Gyr old `Sausage' cluster we find numerous ($59$) H$\\alpha$ emitters above a star-formation rate (SFR) of $0.17$ M$_{\\odot}$ yr$^{-1}$ surprisingly located in close proximity to the shock fronts, embedded in very hot intra-cluster medium plasma. The SFR density for the cluster population is at least at the level of typical galaxies at $z\\sim2$. Down to the same star-formation rate, the possibly dynamically more evolved `Toothbrush' cluster has only $9$ H$\\alpha$ galaxies. The cluster H$\\alpha$ galaxies fall on the SFR-stellar mass relation $z\\sim0.2$ for the field. However, the `Sausage' cluster has an H$\\alpha$ emitter density $>20$ times that of blank fields. If the shock passes through gas-rich cluster galaxies, the compressed gas could collapse into dense clouds and excite star-formation for a few $100$ Myr. This process ultimately leads to a rapid consumption of the molecular gas, accelerating the transformation of gas-rich spirals into ellipticals.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-10-10T20:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "merging galaxy clusters",
      "shock fronts",
      "star-formation rate",
      "hot intra-cluster medium plasma",
      "gas-rich cluster galaxies"
    ],
    "publication": {
      "doi": "10.1093/mnras/stu2519",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2015,
      "month": "Jun",
      "volume": 450,
      "number": 1,
      "pages": 646
    },
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1321639,
      "adsabs": "2015MNRAS.450..646S"
    }
  }
}