THE PHYSICAL CHARACTERISTICS OF THE GAS IN THE DISK OF CENTAURUS A USING THEHERSCHEL SPACE OBSERVATORY Academic Article uri icon

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abstract

  • We search for variations in the disk of Centaurus A of the emission from atomic fine structure lines using Herschel PACS and SPIRE spectroscopy. In particular we observe the [C II](158 $\mu$m), [N II](122 and 205 $\mu$m), [O I](63 and 145 $\mu$m) and [O III](88 $\mu$m) lines, which all play an important role in cooling the gas in photo-ionized and photodissociation regions. We determine that the ([C II]+[O I]$_{63}$)/$F_{TIR}$ line ratio, a proxy for the heating efficiency of the gas, shows no significant radial trend across the observed region, in contrast to observations of other nearby galaxies. We determine that 10 - 20% of the observed [C II] emission originates in ionized gas. Comparison between our observations and a PDR model shows that the strength of the far-ultraviolet radiation field, $G_0$, varies between $10^{1.75}$ and $10^{2.75}$ and the hydrogen nucleus density varies between $10^{2.75}$ and $10^{3.75}$ cm$^{-3}$, with no significant radial trend in either property. In the context of the emission line properties of the grand-design spiral galaxy M51 and the elliptical galaxy NGC 4125, the gas in Cen A appears more characteristic of that in typical disk galaxies rather than elliptical galaxies.

authors

  • Parkin, TJ
  • Wilson, Christine D
  • Schirm, MRP
  • Baes, M
  • Boquien, M
  • Boselli, A
  • Cormier, D
  • Galametz, M
  • Karczewski, OŁ
  • Lebouteiller, V
  • De Looze, I
  • Madden, SC
  • Roussel, H
  • Smith, MWL
  • Spinoglio, L

publication date

  • May 20, 2014