{
  "id": "1906.01890",
  "version": "v1",
  "published": "2019-06-05T09:06:54.000Z",
  "updated": "2019-06-05T09:06:54.000Z",
  "title": "The Evolution of the Interstellar Medium in Post-Starburst Galaxies",
  "authors": [
    "Zhihui Li",
    "K. Decker French",
    "Ann I. Zabludoff",
    "Luis C. Ho"
  ],
  "comment": "29 pages, 13 figures, to be published in ApJ",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "We derive dust masses ($M_{\\rm dust}$) from the spectral energy distributions of 58 post-starburst galaxies (PSBs). There is an anticorrelation between specific dust mass ($M_{\\rm dust}$/$M_{\\star}$) and the time elapsed since the starburst ended, indicating that dust was either destroyed, expelled, or rendered undetectable over the $\\sim$1 Gyr after the burst. The $M_{\\rm dust}$/$M_{\\star}$ depletion timescale, 205$^{+58}_{-37}$ Myr, is consistent with that of the CO-traced $M_{\\rm H_2}/M_{\\star}$, suggesting that dust and gas are altered via the same process. Extrapolating these trends leads to the $M_{\\rm dust}/M_{\\star}$ and $M_{\\rm H_2}/M_{\\star}$ values of early-type galaxies (ETGs) within 1-2 Gyr, a timescale consistent with the evolution of other PSB properties into ETGs. Comparing $M_{\\rm dust}$ and $M_{\\rm H_2}$ for PSBs yields a calibration, log $M_{\\rm H_2}$ = 0.45 log $M_{\\rm dust}$ + 6.02, that allows us to place 33 PSBs on the Kennicutt-Schmidt (KS) plane, $\\Sigma \\rm SFR-\\Sigma M_{\\rm H_2}$. Over the first $\\sim$200-300 Myr, the PSBs evolve down and off of the KS relation, as their star formation rate (SFR) decreases more rapidly than $M_{\\rm H_2}$. Afterwards, $M_{\\rm H_2}$ continues to decline whereas the SFR levels off. These trends suggest that the star-formation efficiency bottoms out at 10$^{-11}\\ \\rm yr^{-1}$ and will rise to ETG levels within 0.5-1.1 Gyr afterwards. The SFR decline after the burst is likely due to the absence of gas denser than the CO-traced H$_2$. The mechanism of the $M_{\\rm dust}/M_{\\star}$ and$M_{\\rm H_2}/M_{\\star}$ decline, whose timescale suggests active galactic nucleus (AGN) or low-ionization nuclear emission-line region (LINER) feedback, may also be preventing the large CO-traced molecular gas reservoirs from collapsing and forming denser star forming clouds.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-06-05T09:06:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "post-starburst galaxies",
      "interstellar medium",
      "large co-traced molecular gas reservoirs",
      "dust mass",
      "low-ionization nuclear emission-line region"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 29,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}