Analytical approximation of the emission line Fe K_α in QSO's spectra

In spectra of many Seyfert galaxies there is a wide emission line of Fe $K_\alpha$. The line profile with two maxima supposes that the line emerges in innermost regions of an accretion disk around a black hole, hence, it is necessary to take into account General Relativity (GR) effects. In order to determine GR processes which occur in active galactic nuclei (AGN) an inverse problem of reconstructing the accreting system parameters from the line profile has to be solved quickly. In this paper we present a numerical approximation of the emission line Fe $K_\alpha$ with analytical functions. The approximation is accomplished for a range of the disk radial coordinate $r$ and the angle $\theta$ between line of sight and perpendicular to the disk and allows one to decrease computing time by $10^6$ times in certain astrophysical problems taking into account all GR effects. The approximation results are available in the Internet at http://www.iki.rssi.ru/people/repin/approx