Soft X-Ray Properties of Seyfert Galaxies in the ROSAT All-Sky Survey
Abstract
We present the results of ROSAT All-Sky Survey observations of Seyfert and IR luminous galaxies from the extended 12 micron galaxy sample and the optically selected CfA sample. Detections are available for 80% (44/55) of the Seyfert 1's and 34% (23/67) of the Seyfert 2's in the 12 micron sample, and for 76% (26/34) of the Seyfert 1's and 38% (6/16) of the Seyfert 2's in the CfA sample. Roughly half of the Seyfert galaxies (mostly Seyfert 1's) have been fitted to an absorbed power-law model, yielding an average photon index of {GAMMA} = 2.26 +/- 0.11 for 43 Seyfert 1's and {GAMMA} = 2.45 +/- 0.18 for 10 Seyfert 2's, with both types having a median value of 2.3. The soft X-ray luminosity correlates with the 12 micron luminosity, with Seyfert 1's having relatively more soft X-ray emission than Seyfert 2's of similar mid-IR luminosities by a factor of 1.6 +/- 0.3. Several physical interpretations of these results are discussed, including the standard unified model for Seyfert galaxies. Infrared luminous non- Seyferts are shown to have similar distributions of soft X-ray luminosity and X-ray-to-IR slope as Seyfert 2's, suggesting that some of them may harbor obscured active nuclei (as has already been shown to be true for several objects) and/or that the soft X-rays from some Seyferts 2's may be nonnuclear. A soft X-ray luminosity function (XLF) is calculated for the 12 micron sample, which is described well by a single power law with a slope of - 1.75. The normalization of this XLF agrees well with that of a hard X-ray selected sample. Several of our results, related to the XLF and the X- ray-to-IR relation, are shown to be consistent with the hard X-ray observations of the 12 micron sample by Barcons et al.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1996
- DOI:
- 10.1086/177962
- arXiv:
- arXiv:astro-ph/9605031
- Bibcode:
- 1996ApJ...471..190R
- Keywords:
-
- GALAXIES: ISM;
- GALAXIES: SEYFERT;
- INFRARED: GALAXIES;
- X-RAYS: GALAXIES;
- Astrophysics
- E-Print:
- AASTeX, 40 pages. Text and Table 2 only. PostScript versions of this file, figures, and Table 1, and a latex version of Table 1 are available by ftp://ftp.astro.ucla.edu/pub/rush/papers, get rmfv*. Accepted by ApJ ~1996 May 10. Should be published in late 1996