Echo mapping of active galactic nuclei

Title

Echo mapping of active galactic nuclei

Creator

Mandal, Amit Kumar - 1740077

Description

Active galactic nuclei (AGN) are the persistent high luminosity sources powered by accretion of matter onto super massive black holes (SMBHs) at their centres. They are known to show flux variation and this property can be used as an effective tool to map the extent of the broad line region (BLR) and the dusty torus that surrounds the central SMBH. Though the mass of the SMBH (MBH) can be directly measured using the dynamics
of stars that are close to the SMBH, this method is limited to objects in the low redshift Universe (z < 0.1). On the other hand, the technique of reverberation mapping (RM) can provide MBH estimate over a range of redshifts. RM is based on the light travel time delayed response of the line emitting gas as well as the re-processed torus emission to changes in the continuum emission from the accretion disk. As of now, MBH measurements are available for more than 100 sources based on RM. The obtained
BLR sizes (RBLR) are found to be correlated with the optical luminosity (L5100) at wavelength 5100 Å. This relationship is obtained based on measurements of AGN available over a limited range of luminosity. Moreover, many of these measurements also have larger error bars. Therefore, there
is an urgent need to increase RM measurements with small errors on more AGN covering a wide range of redshifts to better constrain the RBLR − L5100 relation.

Publisher

CHRIST (Deemed to be University)

Subject

Physics

Language

English

Type

PhD