Rameshan Thimmappa (Department of Physics, Villanova University)
Relativistic jets in radio galaxies provide unique laboratories for investigating particle acceleration and shock physics. Here, I present high-resolution X-ray and optical studies of two nearby radio galaxies, Pictor A and M87. In Pictor A, using Chandra observations, the western hotspot was resolved into a thin shock-front structure, revealing energy-dependent offsets between the X-ray/optical and radio emission. The hotspot also exhibits long-term flux variability and spectral steepening downstream of the shock. In addition, an X-ray filament has been detected in the eastern lobe of Pictor A. For M87, multi-epoch Chandra and Hubble observations of knot HST-1 in the jet reveal a correlation between flux and positional offset during its flare around 2005, along with substantial long-term flux variability and apparent superluminal motion. These observations further suggest that the X-ray and UV/optical emission may originate from physically distinct regions. Together, these studies demonstrate how spatially resolved imaging and multi-epoch variability analyses can probe the internal structure, dynamics, and high-energy synchrotron emission of relativistic jets in active galactic nuclei.
