Multi-band Studies of Blazars with XMM-Newton

Abstract

Blazars are sub-class of the radio-loud Active Galactic Nuclei (AGN), which emit extremely luminous, polarized and non-thermal radiation covering the entire electromagnetic spectrum from a highly compact center (i.e., SMBH). The blazars with higher luminosity and jet angle are known as FSRQs (Flat spectrum radio quasars), while the BL Lac objects show comparatively low luminosity and smaller jet angle (in both cases the jet angle is ≤ 10°). Moreover, the SED synchrotron peak of FSRQs lies in the radio to optical range but for BL Lacs the synchrotron hump peaks in optical to X-ray range. One of the most interesting phenomenon that blazars show is the multi-frequency flux variation on diverse timescales. In the X-ray domain almost all blazars are strong emitters and it is found from studying emission line properties in X-ray spectra, that the X-ray emissions are coming from regions nearer to the SMBH. So, X-ray study of blazars can give deeper insight of the central engine improving our understanding of the source. In this thesis our aim is to understand different physical mechanisms involved with X-ray emission and to get better understanding of different variability properties observed in blazars. In order to investigate this we have undertaken two different approaches : (1) temporal study in multi-frequency domain and (2) X-ray spectral study. The whole work presented in this thesis is based on the blazar observations made by XMM-Newton observatory since its launch.