Comprehensive X-ray Study of Giant Radio Galaxies with XMM-Newton and Chandra

We present a systematic X-ray spectral analysis of 27 giant radio galaxies (GRGs) using archival XMM-Newton and Chandra data. Roughly 44% of the sample show intrinsic absorption (N H,int 10 21, cm-2), while several exhibit narrow Fe K alpha emission lines with equivalent widths up to about 570 eV. Soft X-ray features are also common, including thermal plasma emission (kT about 0.2 --0.8 keV) and ionized absorbers, in some cases consistent with high-velocity outflows. The photon indices are typically hard (median about 1.6), in line with radio-loud AGN. A comparison between nuclear X-ray luminosity and extended radio power shows that many sources host relatively strong X-ray cores compared to their lobes, pointing toward possible restarted nuclear activity. For 10 GRGs with published black hole masses, we explore preliminary relations with X-ray luminosity, Eddington ratio, and photon index. We find a positive trend between M BH and L 2-10, keV, while Eddington ratios show no clear dependence on mass. A tentative negative relation between lambda Edd and hints at inefficient accretion, although confirmation will require larger samples. Overall, GRGs display diverse nuclear conditions and accretion states, supporting scenarios where obscuration, episodic or restarted activity, and low-efficiency accretion shape their long-term evolution.