Gravitational lensing as a tool to probe the gamma-ray dissipation sites of Blazars

Bright gamma-ray flaring events and rapid variability, sometimes on minute timescales, are key signatures of extreme energy dissipation in the relativistic jets astrophysical objects. These timescales reflect extreme particle acceleration, where magnetic energy near the black hole transitions into particle kinetic energy within the jet. However, the detection of rapid variability in high redshift blazar remains challenging due to limited sensitivity of present telescopic facilities. Detecting and studying such high redshift blazar (with supermassive black hole) hold potential on understanding earlier universe and black hole evolution/formation. Gravitationally lensed blazars offer a compelling tool to investigate gamma-ray emission regions specifically at high redshifts. The time delay between lensed signals provides unique constraints on the spatial distribution of these emission sites around the mass weighted center of the lens. We conducted a detailed analysis of 15 years of gamma-ray activity from the lensed blazar PKS 1830-211 to identify emission regions at varying flux levels, comparing them with established radio emission zones. By employing a machine learning-based Gaussian Process Regression, along with advanced time-domain methods like Autocorrelation function and the Double Power Spectrum, we estimated the lensed time delay for flaring epochs as a way to constrain the emission site. Our findings revealed a consistent ~20-day delay across all flaring events, indicating a relatively fixed gamma-ray emission site, likely within the radio core. Interestingly, this delay was significantly shorter than the previously observed ~27-day delay for radio emissions, suggesting that flaring gamma-ray production occurs closer to the central black hole compared to radio emission regions. This work is now accepted for publication in MNRAS. With the upcoming new facilities which will monitor distant universe, this work opens potential to study unexplored high energy universe in new ways