Abstract Details

Name: Debbijoy Bhattacharya
Affiliation: Manipal Centre for Natural Science, Centre of Excellence, Manipal Academy of Higher Education
Conference ID: ASI2020_335
Title : Constraining emission mechanism of active galaxies utilising observations from upcoming X-ray polarimeter POLIX onboard XPoSat
Authors and Co-Authors : Debbijoy Bhattacharya (1), M. Hasan (2), C.S. Stalin (3), B. Paul (4), P. Sreekumar (2). (1) Manipal Centre for Natural Sciences, MAHE, Manipal, (2) Space Science Program Office, ISRO, Bangalore (3) Indian Institute of Astrophysics, Bangalore, (4) Raman Research Institute, Bangalore
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : Blazars are a class of radio-loud active galactic nuclei (AGN) which emit throughout the electromagnetic spectrum and exhibit variability of different timescales ranging from minutes to years. Due to small jet to line-of-sight angle, the observed emission in blazars is primarily originated in jets. Their spectral energy distributions are characterized by a double hump structure, a broad low-frequency component mainly in the radio-optical-UV (sometimes in X-rays) band and a high-frequency component from X-rays to gamma-rays. It is generally accepted that synchrotron emission from ultrarelativistic jet electrons is the source of observed low energy emission (the first hump) in blazars. However, the origin of high energy emission (second hump) is still a matter of debate. Two fundamentally different scenarios are considered namely leptonic and hadronic models. In leptonic scenario, high energy emission is expected to be originated from inverse Comptonization of synchrotron photons by jet electrons. In the case of hadronic model, jet protons are responsible for observed high energy emission through proton synchrotron process and/or decay of neutral pions. The observed broadband spectral energy distribution (SED) of these sources are well explained by both leptonic and hadronic models.  However, the expected polarisation from these two processes are significantly different. Blazars for those optical emissions falls on the first hump, whereas, X-ray emission falls on the second hump of the SED, one can expect a much lower polarisation in X-ray band for leptonic model than the hadronic one. Therefore, future polarisation observations in X-ray energies could play a key role to unveil this puzzle. In this talk, we will discuss how future X-ray polarisation observations from upcoming X-ray polarimeter POLIX onboard XPoSat could help us to differentiate between leptonic and hadronic jets emission scenario in blazars with a demonstration on a list of sources.