Abstract Details

Name: Bhoomika Rajput
Affiliation: Indian Institute of Astrophysics
Conference ID: ASI2020_478
Title : Characterization of the optical and GeV flux variability connection in the bright flat spectrum radio quasars
Authors and Co-Authors : Bhoomika, C.S. Stalin and Sunder Sahayanathan
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : The extragalactic gamma-ray sky is dominated by the blazar class of active galactic nuclei (AGN). These sources with their relativistic jets pointed close to be observer show flux variations over the entire accessible electromagnetic spectrum. By studying flux variations over multiple wavelengths one can probe the multi-wavelength emission sites in blazar jets. According to the leptonic model, the flux variations in the optical and GeV bands of blazars are expected to be correlated. Alternatively, in the hadronic scenario of emission from blazar jets, a correlation between flux variations in the optical and GeV bands need not be expected. To probe the possible connection between optical and GeV emission mechanism in blazar jets we carried out a systematic analysis of the brightest five gamma-ray flat spectrum radio quasars selected from the 3rd Catalog of AGN detected by the Fermi, gamma-ray space telescope namely 3C 454.3, 3C 273, 3C 279, PKS 1510-089 and CTA 102. Our analysis that includes spectral, timing and broad band spectral energy distribution (SED) modeling utilized quasi-simultaneous data acquired in the optical, UV, X-ray and gamma-ray energies spanning 10 years from August 2008 to August 2018. Various behaviors in the flux variability nature of the sources were observed. At certain epochs, we found that the optical and gamma-ray flux variations are closely correlated. However, we also noticed instances where there are optical flares without gamma-ray counterparts and gamma-ray flares without optical counterparts. Broad band SED modeling of these epochs using one zone leptonic emission models hints that the instances of the distinct behaviors of optical flares (without gamma-ray counterparts) or gamma-ray flares (without optical counterparts) might be due to changes in magnetic fields, bulk Lorentz factor and electron energy density and also changes in the size of the emission region. Details of this work will be presented.