Astronomy and Astrophysics – Astrophysics
Scientific paper
1996-06-27
Astrophys.J. 477 (1997) 602
Astronomy and Astrophysics
Astrophysics
49 pages, 10 figures. LaTeX with encapsulated postscript. To appear in the Astrophysical Journal. Also available via http://
Scientific paper
10.1086/303721
We present evidence for widespread relativistic effects in the central regions of active galactic nuclei. In a sample of 18 Seyfert 1 galaxies observed by \asca, 14 show an iron K$\alpha$ line which is is resolved, with mean width $\sigma_{\rm K\alpha}=0.43\pm 0.12$~keV for a gaussian profile (Full Width at Half Maximum, FWHM$\sim 50,000$~km s$^{-1}$). However, many of the line profiles are asymmetric. A strong red wing is indicative of gravitational redshifts close to a central black hole and accretion disk models provide an excellent description of the data. The peak energy of the line is 6.4~keV, indicating that it arises by fluorescence in near-neutral material. Our fits imply a low inclination for the disk in these Seyfert 1 galaxies, with a mean of 30\deg, consistent with orientation-dependent unification schemes. Differences in the line profiles from source-to-source imply slight variations in geometry, which cannot be accounted for solely by inclination. In most cases, we require that the line emission arises from a range of radii. Although a small contribution to the emission from a region other than the disk is not ruled out, it is not generally required and has little effect on our conclusions regarding the disk line. Our data are fit equally well with rotating (Kerr) and non-rotating (Schwarzschild) black hole models. We find a mean spectral index in the 3-10 keV range of $<\Gamma_{3-10}>=1.91\pm 0.07$ after accounting for the effects of reflection. Such observations probe the innermost regions of AGN, and arguably provide the best evidence yet obtained for the existence of super-massive black holes in the centers of active galaxies.
George Ian Michael
Mushotzky Richard F.
Nandra Kirpal
Turner Tracey Jane
Yaqoob Tahir
No associations
LandOfFree
ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-266097