Abstract Details

Name: Souradip Bhattacharyya
Affiliation: Presidency University
Conference ID: ASI2020_234
Title : Stationarity and Non-Linearity of Blazar Variability
Authors and Co-Authors : Souradip Bhattacharyya(Presidency University), Ritesh Ghosh(Visva-Bharati University), Ritaban Chatterjee(Presidency University), Nabanita Das(Presidency University)
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : We analyze X-ray light curves of the blazars Mrk 421, PKS 2155-304, and 3C 273 using observations by the Soft X-ray Telescope onboard AstroSat and archival XMM-Newton data. We use light curves of length 30-90 ks each from 3-4 epochs for all three blazars. We show that the power spectral density(PSD) of the X-ray variability of the individual blazars are consistent within uncertainties across the epochs. This indicates that construction of broadband PSD using light curves from different epochs is accurate. We use other tests including S-statistic and excess variance in order to test the stationarity of the variability. We find that the light curves at most epochs are consistent with stationarity but the variability of PKS 2155-304 at one of the epochs shows multiple indication of non-stationarity. We find a linear relationship between root-mean-squared amplitude of variability at shorter timescale and the mean flux level at longer timescale for light curves of Mrk 421 across light curves separated by decades as well as light curves spanning ~5 days and ∼10 yr. The presence of a flux-rms relation over very different timescales implies that, similar to X-ray binaries and Seyfert galaxies, longer and shorter timescale variability are connected in blazars. While in the former this is consistent with models of variability involving propagating fluctuations in the accretion disk, here it can provide constraints on the models of variability in the blazar jets.