The Physical Conditions of the X-ray Emission Line Regions in the Circinus Galaxy

Abstract

We present a detailed X-ray spectral analysis of the Circinus Galaxy using archival data obtained with the ASCA satellite. The spectrum shows numerous emission lines in the soft X-ray band from highly ionized ions, as well as Compton reflection and fluorescent lines from neutral or near-neutral matter. We analyze the spectrum in the context of a self-consistent recombination cascade model and find that a nearly flat differential emission measure (DEM) distribution in ionization parameter fits the data. For a fixed solid angle distribution of matter surrounding a point source, this corresponds to a run of electron density of the form, n(r) ~ r^(-3/2), which is suggestive of Bondi accretion onto a central compact mass. Using this density profile and comparing the resulting emission spectra with the ASCA data, the size of the X-ray emission line region is estimated to be < 1 kpc. We also show that the derived density as a function of radius is compatible with the X-ray recombination line emission region being the confining medium of the coronal line regions.

21 pages including 8 figures and 4 tables; accepted for publication to the Astrophysical Journal

References in corpus (2)

• The X-Ray Spectrum and Global Structure of the Stellar Wind in Vela X-1
• Soft X-ray spectroscopy of Compton-thick Seyfert 2 galaxies with BeppoSAX

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• Flux and spectral variations in the Circinus Galaxy
• A characterization of the NGC 4051 soft X-ray spectrum as observed by XMM-Newton
• Evidence for Radiation Pressure Compression in the X-ray Narrow Line Region of Seyfert galaxies
• 3C 33: another case of photoionized soft X-ray emission in radio galaxies
• Well behaved class of Heintzmann's solution within $f(R,T)$ framework
• Active Galactic Nuclei and their demography through cosmic time