| Name: ARIT BALA |
| Affiliation: Presidency University, KOLKATA |
| Conference ID: ASI2026_197 |
| Title: Probing the Nature of Magnetic Field in Blazar Jets from Multi-Wavelength Variability |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Arit Bala(Presidency University, Kolkata-700073, India), Ritaban Chatterjee(Presidency University, Kolkata-700073, India) |
| Abstract: Blazar emission varies significantly at longer (days to years) timescales across the electromagnetic spectrum and at shorter (sub-day) timescales at optical, X-ray and gamma-rays energies. The longer-timescale variability is usually explained by the injection of energetic particles by shocks propagating down the jet and subsequent radiative cooling of those particles in the shock-in-jet scenario. However, the source of the observed minutes-hours timescale variability has been elusive. We present a numerical model, in which a shock moves down the jet and energizes the previously quiescent electrons in consecutive “cells”. The electrons subsequently cool via synchrotron and inverse-Compton processes. In this ‘multi-zone’ model, the magnetic field in each cell may be different and the electron energy distribution in each cell may evolve independently due to cooling. Our model can reproduce the red-noise nature of the variability and strong correlation among multiple wave bands with zero time delay as observed in blazars. We find that shorter-timescale synchrotron variability, as observed at X-ray and optical emission in many blazars, may be generated by the fluctuations of the magnetic field (few to few tens of percent) in the neighboring cells. We find that short-timescale fluctuations in the GeV emission generated by the external Compton process, which does not depend on the magnetic field, may be produced by imposing equipartition of energy between the magnetic field and particles. A non-zero time lag among, e.g., GeV and optical variability, as observed in a small fraction of blazar flares, may be reproduced in very specific configurations of the magnetic field, for example, if the magnetic field contains large angular variation in its direction among neighbouring cells. Comparison of our model results with observed data, as a tool complimentary to polarization observations, can be effectively used to constrain the nature of magnetic field in blazar jets. |
