Broad spectral lines in AGNs and supermassive black hole mass measurements

Abstract

The mass measurement of supermassive black holes (SMBHs) is a very complex task. Between several methods for SMBH mass measurements, some of them use the spectral lines, which indicate the motion of the emitting/absorbing material around an SMBH. Mostly there is assumption of virialization of line emitting gas in the region close to SMBHs that is used for their mass measurements. In this paper we will give an overview of methods for the SMBH mass measurements using broad emission spectral lines observed in Type 1 AGNs. First we give the basic idea to use the parameters of broad lines to SMBH mass measurements. After that we give an overview of broad lines from X-ray (Fe kα) to the IR (Pashen and Brecket lines) which have been used for SMBH mass estimates. Additionally, we describe and discuss a new method for SMBH mass measurements using the polarization in the broad lines emitted from Type 1 AGNs.

The review was presented at 12th Serbian Confer- ence on Spectral Line Shapes in Astrophysics in the special session "Broad lines in AGNs: The physics of emission gas in the vicinity of super-massive black hole" (In memory of the life and work of dr Alla Ivanovna Shapovalova). Revised version is accepted to be published in Open Astronomy