Abstract Details

Name: Priyanka Rani
Affiliation: Inter-University Centre for Astronomy and Astrophysics
Conference ID: ASI2021_479
Title : Temporal and Spectral Characteristics of Active Galactic Nuclei in X-rays using NuSTAR
Authors and Co-Authors : C.S. Stalin, IIA
Abstract Type : Oral
Abstract Category : Thesis
Abstract : The primary X-ray emission in active galactic nuclei (AGN) is believed to originate in a compact region called the corona situated very close to the central supermassive black hole (SMBH) and the accretion disk. The very central region of AGN is also very difficult to probe directly, as it is beyond the reach of any direct imaging telescopes. The motivation behind this thesis is therefore to probe the central regions of AGN via timing and spectral analysis of the hard X-ray emission received from them. Towards this, data in the 3-79 keV band from the Nuclear Spectroscopic Telescope Array (NuSTAR) was used. For timing analysis we used data for a total of 335 AGN (557 sets of observations) that comprises of 24 BLLac objects (BL Lacs), 24 flat spectrum radio quasars (FSRQs), 20 Narrow Line Seyfert 1 (NLSy1) galaxies, 121 Seyfert 1 galaxies and 146 Seyfert 2 galaxies. Our analysis indicates that on hour like time scales, blazars (that includes FSRQs and BL Lac objects) are more variable that their radio-quiet counterparts namely the Seyfert galaxies, which is attributed to the contribution of relativistic jets to the observed X-ray emission in blazars. We also found brighter AGN to be less variable as well as AGN powered by more massive black holes to be less variable. For spectral analysis we carried our several model fits to a sample of 12 sources to derive the cut-off energy (E_cut) as it carries information on the physical characteristics of the corona. In this thesis we derived first time E_cut measurements for 11 sources and an upper limit for one. Details of the work will be presented.