Abstract Details

Name: Sanna Gulati
Affiliation: Manipal Centre for Natural Sciences, Centre of Excellence, Manipal Academy of Higher Education
Conference ID: ASI2020_319
Title : Long term behaviour of active galaxy NGC 1275 using multi-wavelength observations
Authors and Co-Authors : Sanna Gulati*, Debbijoy Bhattacharya*, Subir Bhattacharyya**, Nilay Bhatt**, C.S. Stalin*** *Manipal Centre for Natural Sciences, Centre of Excellence, Manipal Academy of Higher Education, Manipal **Bhabha Atomic Research Centre, Mumbai ***Indian Institute of Astrophysics, Bangalore
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : Misaligned active galaxies (MAGN) have their relativistic jets oriented at larger angles to the line of sight of the observer.  Since gamma-rays are primarily emitted from jet and emission from the jet falls off rapidly with increasing jet to line-of-sight angle, MAGN are expected to be very weak gamma-ray emitter. Hence, they constitute a small fraction of the sources detected by Large Area Telescope on-board the Fermi Gamma-Ray Space Telescope. Among ~50 MAGN detected by Fermi in it’s eight years of observation (2008 - 2016), NGC 1275 is one of the brightest MAGN in gamma-rays and is known to exhibit variability over short as well as long time scales. It is located at the center of the Perseus cluster and is classified as Fanaroff-Riley type 1 radio galaxy. We carried out a detailed long-term and short-term temporal behaviour of the source in gamma-rays utilising ~11 years of Fermi observations and it’s possible correlation with other wavelengths. An increase in baseline flux over a period of ~9 years (2008 - 2017) in gamma-rays is noticed, which is followed by a large single flare for the next two years (2017 - 2019). Broad-band spectral energy distribution utilising observations from Fermi, Swift, AstroSat and other observatories in different states of gamma-ray light curve, associated modelling and hence the possible physical scenario behind such unusual long term behaviour of NGC 1275 will be presented.