{
  "id": "1409.0009",
  "version": "v1",
  "published": "2014-08-29T20:00:20.000Z",
  "updated": "2014-08-29T20:00:20.000Z",
  "title": "The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation",
  "authors": [
    "Martin Sparre",
    "Christopher C. Hayward",
    "Volker Springel",
    "Mark Vogelsberger",
    "Shy Genel",
    "Paul Torrey",
    "Dylan Nelson",
    "Debora Sijacki",
    "Lars Hernquist"
  ],
  "comment": "15 pages, 15 figures, submitted to MNRAS, Data is available at http://martinsparre.com/dataproducts The Illustris website can be found at http://www.illustris-project.org",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Understanding the physical processes that drive star formation is a key challenge for galaxy formation models. In this article we study the tight correlation between the star formation rate (SFR) and stellar mass of galaxies at a given redshift, how halo growth influences star formation, and star formation histories of individual galaxies. We study these topics using Illustris, a state-of-the-art cosmological hydrodynamical simulation of galaxy formation. Illustris reproduces the observed relation (the star formation main sequence; SFMS) between SFR and stellar mass at redshifts z=0 and z=4, but at intermediate redshifts of z~2, the simulated SFMS has a significantly lower normalisation than reported by observations. The scatter in the relation is consistent with the observed scatter. However, the fraction of outliers above the SFR-stellar mass relation in Illustris is less than that observed. Galaxies with halo masses of ~10^{12} solar masses dominate the SFR density of the Universe, in agreement with the results of abundance matching. Furthermore, more-massive galaxies tend to form the bulk of their stars at high redshift, which indicates that `downsizing' occurs in Illustris. We also studied the star formation histories of individual galaxies, including the use of a principal component analysis decomposition. We find that for fixed stellar mass, galaxies that form earlier have more-massive black holes at z=0, indicating that star formation and black hole growth are tightly linked processes in Illustris. While many of the properties of normal star-forming galaxies are well-reproduced in the Illustris simulation, forming a realistic population of starbursts will likely require higher resolution and probably a more sophisticated treatment of star formation and feedback from stars and black holes.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-08-29T20:00:20.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "star formation main sequence",
      "stellar mass assembly",
      "illustris simulation",
      "black hole",
      "star formation histories"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1093/mnras/stu2713",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2015,
      "month": "Mar",
      "volume": 447,
      "number": 4,
      "pages": 3548
    },
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015MNRAS.447.3548S"
    }
  }
}