{
  "id": "2506.17663",
  "version": "v1",
  "published": "2025-06-21T09:46:04.000Z",
  "updated": "2025-06-21T09:46:04.000Z",
  "title": "Diffuse X-Ray-emitting Gas in the Central Region of Star-Forming Galaxies",
  "authors": [
    "Chunyi Zhang",
    "Junfeng Wang"
  ],
  "comment": "17 pages, 8 figures, 4 tables, accepted for publication in ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The interstellar medium of galaxies, with temperatures reaching several million degrees, provides a pivotal perspective for understanding the physical and chemical properties of star formation, galactic evolution, and their associated feedback mechanisms. We use archival data from $Chandra$ observations to extract the diffuse X-ray emission from 23 nearby star-forming galaxies and study its correlation with star formation activity in the central region of these galaxies. The surface brightness profile of each galaxy presents a sharp decrease in the central region of $\\thicksim$0.3$-$2 kpc and then varies slowly outside this range. Compared to the global relation between the diffuse thermal X-ray luminosity from hot gas ($L_{\\rm 0.5 - 2\\,keV}^{\\rm gas}$) and the star formation rate (SFR), we found a super-linear relation of ${\\rm log}(L_{\\rm 0.5-2\\,keV}^{\\rm gas} /{\\rm erg\\,s^{-1}})=1.34\\,{\\rm log}({\\rm SFR}/{M_{\\rm \\odot}}\\,{\\rm yr^{-1}})+40.15$ for the center of these sample galaxies. This result suggests that more intense stellar feedback is associated with stronger star formation activity in the central region of star-forming galaxies, where more energy output from supernovae (SNe) and stellar winds is converted into X-ray flux. Furthermore, the slope of the $L_{\\rm 0.5 - 2\\,keV}^{\\rm gas}$$-$SFR relation anticorrelates with spatial scale in the galactic central region. This indicates that the characteristics of central hot gas emission are gradually averaged over larger areas. The diffuse X-ray luminosity also shows a good correlation with molecular gas, stellar mass, and mid-plane pressure traced by the baryonic mass, although these relations show relatively large scatter.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-06-21T09:46:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "central region",
      "star-forming galaxies",
      "diffuse x-ray-emitting gas",
      "diffuse thermal x-ray luminosity",
      "central hot gas emission"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}