ar X iv : a st ro - p h / 96 06 16 9 v 2 2 6 A ug 1 99 6 ASCA observations of Seyfert 1 galaxies : II . Relativistic Iron K α emission
نویسندگان
چکیده
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 Kα line which is is resolved, with mean width σ Kα = 0.43 ± 0.12 keV for a gaussian profile (Full Width at Half Maximum, FWHM∼ 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 • , 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 < Γ 3−10 >= 1.91 ± 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.
منابع مشابه
ar X iv : a st ro - p h / 96 06 16 9 v 1 2 7 Ju n 19 96 ASCA observations of Seyfert 1 galaxies : II . Relativistic Iron K α emission
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 Kα line which is is resolved, with mean width σ Kα = 0.43 ± 0.12 keV for a gaussian profile (Full Width at Half Maximum, FWHM∼ 50, 000 km s −1). However, many of the line profiles are asymmetric. A strong red wing is ind...
متن کاملar X iv : a st ro - p h / 97 08 23 1 v 1 2 5 A ug 1 99 7 ASCA observations of type - 2 Seyfert Galaxies : III Orientation and X - ray Absorption
We discuss the spectral properties of a sample of type-2 Seyfert galaxies based upon the analysis of ASCA data. In this paper we consider the sources for which the X-ray spectra appear to be dominated by the nuclear continuum, transmitted through a large column of absorbing material. We find that both Seyfert-2 galaxies and NELGs show iron Kα line profiles indicative of reprocessing of nuclear ...
متن کاملar X iv : a st ro - p h / 98 08 16 6 v 1 1 7 A ug 1 99 8 Accretion Disk Line Emission in AGN : A Devil ’
We review the evidence for AGN optical and X-ray broad line emission from an accretion disk. We argue that there is little, if any, statistical evidence to support this assertion. The inconsistency is strongest for the rare class of Balmer profiles that show double peaks. The line profiles predicted by a simple illuminated disk model are often incompatible with the observations. We suggest that...
متن کاملar X iv : a st ro - p h / 96 08 16 5 v 1 2 6 A ug 1 99 6 High redshift radio galaxies with the VLT
متن کامل
ar X iv : a st ro - p h / 96 08 17 0 v 1 2 6 A ug 1 99 6 ASCA observations of Seyfert 1 galaxies : I . Data Analysis , Imaging and Timing
We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by ASCA. The imaging data reveal a number of serendipitous hard X-ray sources in some source fields, but none contribute significantly to the hard X-ray flux of the AGN. All but one of the Seyferts show evidence for variability on timescales of minutes-hours, with...
متن کامل