Suzaku Observation of the Brightest Broad-Line Radio Galaxy 4C 50.55 (IGR J 21247+5058)

TL;DR

This study presents a detailed Suzaku X-ray analysis of the brightest broad-line radio galaxy 4C 50.55, revealing its spectral features, corona properties, and disk structure, with implications for jet production in black hole systems.

Contribution

It provides the first comprehensive broadband X-ray spectral analysis of 4C 50.55, highlighting its corona characteristics and disk-corona structure, and suggests a truncated disk with an optically thick corona.

Findings

Spectral fitting indicates a cut-off power law with reflection and absorption.

Corona is optically thick with low electron temperature (~30 keV).

Disk appears truncated or covered by corona, affecting relativistic line features.

Abstract

We report the results from a deep Suzaku observation of 4C 50.55 (IGR J 21247+5058), the brightest broad-line radio galaxy in the hard X-ray (> 10 keV) sky. The simultaneous broad band spectra over 1-60 keV can be represented by a cut-off power law with two layers of absorption and a significant reflection component from cold matter with a solid angle of \Omega/2\pi \approx 0.2. A rapid flux rise by ~ 20% over 2 \times 10^4 sec is detected in the 2-10 keV band. The spectral energy distribution suggests that there is little contribution to the total X-ray emission from jets. Applying a thermal Comptonization model, we find that corona is optically thick (\tau_e \approx 3) and has a relatively low temperature (kT_e \approx 30 keV). The narrow iron-K emission line is consistent with a picture where the standard disk is truncated and/or its inner part is covered by optically thick Comptonizing corona smearing out relativistic broad line features. The inferred disk structure may be a common feature of accretion flows onto black holes that produce powerful jets.