Abstract Details

Name: INDRANI PAL
Affiliation: INDIAN INSTITUTE OF ASTROPHYSICS, BANGALORE
Conference ID: ASI2020_267
Title : Coronal Temperature Variation in Active Galactic Nuclei
Authors and Co-Authors : Indrani Pal & Dr. C.S.Stalin
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : The variable hard X-ray (> 2 keV) emission observed commonly in active galactic nuclei is believed to originate in a hot and compact region called the corona having dimension of the order of 3-10 gravitational radii in radius and height above the black hole. The observed X-ray emission is thus due to thermal Comptonization of the soft accretion disk photons by the hot electrons in the corona leading to a power law shaped X-ray spectrum with a high energy cut-off. In non-jetted AGN, the corona is responsible for most of the X-ray emission above 2 keV. In spite of the corona being an integral part of AGN, details such as its nature,geometry, location and the physical mechanisms that power it are still unknown entities. However, the launch of NuSTAR in the year 2012 has started to provide observational leads (through measurement of high energy cut-off) to our understanding of the corona in AGN, owing to its high sensitivity beyond 10 keV. Available NuSTAR observations, in addition to measuring the high energy cut-off can also be used to probe variation in the temperature of the corona. With the prime motivation to look for variations in the coronal temperature if any, which in turn can provide very important inputs to our understanding of the corona, we carried out a systematic investigation of AGN having more than one epoch of observations from NuSTAR. This criteria lead us to a sample of 25 AGN. From detailed spectral analysis we found that 20% of our sample showed variation in the coronal temperature. We also examined correlation of coronal temperature with various physical parameters of the AGN.Details of these interesting results will be presented.