16 papers
Probing the High-Energy Emission of the VHE-emitting Changing-Look Blazar B2 1420+32
Anjum Peer, Zahir Shah, Sikandar Akbar +2
We present a multi-wavelength temporal and spectral study of the changing-look blazar B2~1420+32 using \emph{Fermi}-LAT, \emph{Swift}-XRT, and \emph{Swift}-UVOT data from MJD~58818…
Spectral State Switching in Mrk 421: Results from the AstroSat LAXPC/SXT Observations
Sikandar Akbar, Zahir Shah, Ranjeev Misra +1
We carried a detailed time and flux resolved X-ray spectral analysis of the high-synchrotron-peaked blazar Mrk\,421 using simultaneous LAXPC20 and SXT observations. The 100\,s binn…
Exploring the Transitional Parameter Space of Blazars using Gamma-ray and X-ray Population Diagnostics
Zahoor Malik, Sikandar Akbar, Zahir Shah
We investigate the -ray and X-ray population properties of changing-look blazars (CLBs) using sources from the Fourth \textit{Fermi} LAT Source Catalog Data Release 4 (4FGL-DR4…
Advance warning of -ray blazar flares from \textit{Fermi}-LAT light curves: a strictly causal machine-learning backtest
Zahir Shah, Sikandar Akbar
Long-term \textit{Fermi}-LAT monitoring makes it possible to ask whether a blazar light curve shows signs of an upcoming flare before the flare becomes obvious in the -ray emis…
Indication of gamma-Ray Quasi-periodicity in GB6 J1037+5711 from Multi-technique Timing Analysis
Zahoor Malik, Sikandar Akbar, Zahir Shah +1
We report the indication of a long-term quasi-periodic oscillation (QPO) in the -ray emission of the BL Lac object 4FGL J1037.7+5711 (GB6 J1037+5711) using more than 17 years o…
Characterizing Short-Timescale Optical Variability in Non-blazar Active Galactic Nucleus PKS~052136 Using TESS
Sikandar Akbar, Zahir Shah
We present a systematic analysis of high-cadence optical light curves of the non-blazar AGN PKS~052136 obtained with \textit{TESS} across three sectors: Sectors~5 and~6 (Cycle~1…