{
  "id": "2410.14526",
  "version": "v1",
  "published": "2024-10-18T15:08:19.000Z",
  "updated": "2024-10-18T15:08:19.000Z",
  "title": "X-ray Spectroscopy of the Dwarf Nova Z Chamaeleontis in Quiescence and Outburst Using the XMM-Newton Observatory",
  "authors": [
    "Solen Balman",
    "Eric M. Schlegel",
    "Patrick Godon",
    "Jeremy J. Drake"
  ],
  "comment": "27 Pages, 8 Figures, and 5 Tables, accepted to be published in the Astrophysical Journal, in press",
  "categories": [
    "astro-ph.HE",
    "physics.atom-ph",
    "physics.plasm-ph"
  ],
  "abstract": "We present X-ray spectroscopy of the SU UMa-type dwarf nova (DN) Z Cha using the EPIC and RGS instruments onboard the XMM-Newton Observatory. The quiescent system can be modeled by collisional equilibrium or nonequilibrium plasma models, yielding a kT of 8.2-13.0 keV at a luminosity of (5.0-6.0)$\\times$10$^{30}$ erg/s. The spectra yield better reduced $\\chi^{2}$ using partial covering absorbers of cold and photoionized nature. The ionized absorber has an equivalent N$_H$=(3.4-5.9)$\\times$10$^{22}$ cm$^{-2}$ and a log($\\xi$)=3.5-3.7 with (50-60)% covering fraction when VNEI model (XSPEC) is used. The line diagnosis in quiescence shows no resonance lines with only detected forbidden lines of Ne, Mg, Si. The H-like C, O, Ne, and Mg are detected. The strongest line is O VIII with (2.7-4.6)$\\times$10$^{-14}$ erg/s/cm$^2$. The quiescent X-ray emitting plasma is not collisional and not in ionization equilibrium which is consistent with hot ADAF-like accretion flows. The line diagnosis in outburst shows He-like O, and Ne with intercombination lines being the strongest along with weaker resonance lines. This indicates the plasma is more collisional and denser, but yet not in a collisional equilibrium, revealing ionization timescales of (0.97-1.4)$\\times$10$^{11}$ s cm$^{-3}$. The R-ratios in outburst yield electron densities of (7-90)$\\times$10$^{11}$ cm$^{-3}$ and the G-ratios yield electron temperatures of (2-3)$\\times$10$^{6}$ K. The outburst luminosity is (1.4-2.5)$\\times$10$^{30}$ erg/s. The flow is inhomogeneous in density. All detected lines are narrow with widths limited by the resolution of RGS yielding Keplerian rotational velocities $<$1000 km/s. This is too low for boundary layers, consistent with the nature of ADAF-like hot flows.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-10-18T15:08:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray spectroscopy",
      "xmm-newton observatory",
      "quiescence",
      "su uma-type dwarf nova",
      "chamaeleontis"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 27,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}