Abstract Details

Name: Abhijit Kayal
Affiliation: Physical Research Laboratory
Conference ID: ASI2021_319
Title : AstroSat/LAXPC hard X-ray observations of Compton-thick AGN
Authors and Co-Authors : Abhijit Kayal (Physical Research Laboratory, Ahmedabad, India), Veeresh Singh (Physical Research Laboratory, Ahmedabad, India), Santosh Vadawale (Physical Research Laboratory, Ahmedabad, India), Mithun Neelkandan PS (Physical Research Laboratory, Ahmedabad, India), Claudio Ricci (Nucleo de Astronomia, Universidad Diego Portales, Santiago, Chile), Gulab Dewangan (Inter-University Centre for Astronomy and Astrophysics, Pune, India), Poshak Gandhi (University of Southampton, UK)
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : X-ray emission in Active Galactic Nuclei (AGN) arising mainly from the accretion disk and corona is believed to be absorbed and scattered by circumnuclear material. The geometry of reprocessing material is conventionally thought to be of a toroidal-shaped gaseous and dusty structure. However, more recent observations favor a clumpy obscuring medium composed of an equatorial thin disk and a polar-extended cone-like structure. Broad-band X-ray spectral modelling can give us important insights as it carries imprints of absorption and scattering caused by the circumnuclear reprocessing material. Using AstroSat/LAXPC and NuSTAR observations, we attempt to understand the nature of reprocessing material by modelling the broad-band X-ray spectrum of a nearby Compton-thick AGN, namely Circinus galaxy. We find that the broad-band hard X-ray spectrum can be fitted with a model considering the reprocessing of X-ray emission from a putative torus viewed edge-on with column density much higher than the Compton-thick limit (N_H > 1.2×10^24 cm^-2). AstroSat and NuSTAR observations also allow us to investigate hard X-ray flux and spectral variability on various time-scales. In this talk, I shall discuss the importance of our AstroSat/LAXPC observations in unveiling the nature of heavily obscured AGN termed as Compton-thick AGN.