Abstract Details

Affiliation: MCNS, Manipal University
Conference ID: ASI2017_1372
Title : Unusual long term low activity states of EGRET Blazars in the Fermi Era
Authors and Co-Authors : Krishna Mohana A, MCNS, Manipal University Sanna Gulati, MCNS, Manipal University, Subir Bhattacharyya, Astrophysical Division, BARC, Nilay Bhatt, Astrophysical Division, BARC, P. Sreekumar, IIA, C. S. Stalin, IIA
Abstract Type : Oral
Abstract Category : Extragalactic astronomy
Abstract : We examine the long term (nearly 10 years) gamma-ray variability of blazars observed by EGRET and Fermi and find that 10 EGRET-detected flat spectrum radio quasars (FSRQs) were not present in any of the Fermi catalogue (during the first four years of Fermi observation). A search for the Fermi counterparts of these sources was carried out using seven years of Fermi data which showed that five of these sources are at their low states during the Fermi era. This result indicates that FSRQs exhibit long term quiescent state (more than 7 years) and suggests a jet inactive state probably because of decrease in jet fuelling and/or reduction in soft photon density. Apart from limited X-ray observations for one source, other sources were not monitored at other wavelengths. These low gamma-ray states might be due to the slow variations in accretion power in the source. This change in the accretion power in these sources indicates a possible change of state in the accretion flow as observed in black hole X-ray binaries. Also, 37 new gamma-ray sources are detected during the course of this analysis. Since that most of the EGRET and Fermi sources belong to the AGN class, majority of these new sources are expected to be associated with AGN.