Abstract Details

Name: Pankaj Kushwaha
Affiliation: Aryabhatta Research Institute of Observational Sciences, Nainital, India
Conference ID: ASI2021_541
Title : Deciphering the Nature of the Re-emerged Broadband Emission seen during the 2020 Multi-wavelength Activity of Blazar OJ 287
Authors and Co-Authors : Pankaj Kushwaha (Aryabhatta Research Institute of Observational Sciences (ARIES))
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : OJ 287 is a BL Lacertae object – a subclass of active galactic nuclei that has a powerful relativistic jet of plasma roughly directed towards us but lacks any strong emission line features. The most intriguing observational aspect of this source is a recurrent outburst in optical bands every ~12-yr. This recurring outburst is the basis of the claim of the source being a binary black hole system with recurring flares resulting due to the interaction dynamics leading either to jet precession or increased accretion. In April 2020, the source underwent a strong optical to X-ray flux enhancement, reaching its second brightest recorded X-ray flux. Our multi-wavelength spectral and temporal study shows that strong enhancement is due to a drastic change in the X-ray spectrum of the source. The concurrent MeV-GeV emission also shows a strong change in the spectrum and the modified broadband infrared to MeV-GeV emission appears like that of an additional high-energy-peaked blazar emission component. However, our systematic spectro-temporal evolution shows that the high-energy end of the emission component, responsible for an extremely soft X-ray spectrum, is highly dynamic – changes from a power-law spectrum to one like a cutoff over a duration of few days. We will present our results from a detailed and systematic exploration of this new emission component, its nature, connection with the recurring ~12-yr optical flares, and its implications on the proposed models of the recurring optical flares.