Nuclear X-ray properties of the peculiar radio-loud hidden AGN 4C+29.30

TL;DR

This study analyzes the X-ray emission of the radio galaxy 4C+29.30 across a broad energy range, revealing complex absorption and reflection features, variability, and characteristics of a hidden, radio-loud AGN with a supermassive black hole.

Contribution

First detailed X-ray spectral analysis of 4C+29.30 revealing its complex absorption, reflection, and variability, suggesting it is a hidden, radio-loud AGN with a thick torus.

Findings

X-ray spectrum shows intrinsic power-law with Gamma ~ 1.56 and cold absorption N_H ~ 5x10^{23} cm^{-2}

Reflection component less absorbed, with N_H < 2.5x10^{22} cm^{-2}

X-ray variability explained by normalization changes rather than absorption variations

Abstract

We present results from a study of a nuclear emission of a nearby radio galaxy, 4C+29.30, over a broad 0.5-200 keV X-ray band. This study used new XMM-Newton (~17 ksec) and Chandra (~300 ksec) data, and archival Swift/BAT data from the 58-month catalog. The hard (>2 keV) X-ray spectrum of 4C+29.30 can be decomposed into an intrinsic hard power-law (Gamma ~ 1.56) modified by a cold absorber with an intrinsic column density N_{H,z} ~ 5x10^{23} cm^{-2}, and its reflection (|Omega/2pi| ~ 0.3) from a neutral matter including a narrow iron Kalpha emission line at the rest frame energy ~6.4 keV. The reflected component is less absorbed than the intrinsic one with an upper limit on the absorbing column of N^{refl}_{H,z} < 2.5x10^{22} cm^{-2}. The X-ray spectrum varied between the XMM-Newton and Chandra observations. We show that a scenario invoking variations of the normalization of the power-law is favored over a model with variable intrinsic column density. X-rays in the 0.5-2 keV band are dominated by diffuse emission modeled with a thermal bremsstrahlung component with temperature ~0.7 keV, and contain only a marginal contribution from the scattered power-law component. We hypothesize that 4C+29.30 belongs to a class of `hidden' AGN containing a geometrically thick torus. However, unlike the majority of them, 4C+29.30 is radio-loud. Correlations between the scattering fraction and Eddington luminosity ratio, and the one between black hole mass and stellar velocity dispersion, imply that 4C+29.30 hosts a black hole with ~10^8 M_{Sun} mass.