High Energy Physics Seminars

Spectro-temporal features of microquasar and blazar sources: clues regarding underlying accretion-jet physics

by Dr. Anuvab Banerjee (S. N. Bose National Centre for Basic Sciences, Kolkata)

Thursday, January 19, 2023 from to (Asia/Kolkata)
at D-405
Active galactic nuclei are powerful sources of multiwavelength emission that demonstrate large amplitude flux variability across different wavebands, limiting the location and size of the emission regions. An investigation into their broadband spectral energy distribution (SED) and variability properties provides important clues regarding their physical configuration and accretion flow properties. Owing to the underlying red noise component and idiosyncrasies related to blazar lightcurves (such as aliasing), we employ a bunch of sophisticated mathematical techniques (such as the weighted wavelet transform, periodogram peak significance detection using Monte Carlo simulation, etc.) to detect statistically significant periodicity components both in gamma-ray and optical lightcurves of blazars. The broadband SED is generally well represented by a one-zone leptonic scenario where the high energy hump is produced by the inverse Comptonization of the synchrotron seed photons via synchrotron self-Compton or external Comptonization processes. However, in some cases e.g., TeV blazars with high variability, the one-zone model seems inadequate, and we need to resort to other scenarios such as hadronic processes. Due to the longer time scales required for significant flux variability in blazars compared to black hole X-ray binaries, a spectro-temporal investigation on microquasar sources also provides significant insights into accretion flow dynamics around compact objects and informs our understanding of accretion flows in general, particularly the disk-jet connection. I will discuss some findings in this context as well.