X-Ray view of Misaligned AGNs

TL;DR

This paper analyzes X-ray data of misaligned AGNs, revealing differences in accretion efficiency, emission mechanisms, and jet environments between FRIs and FRIIs, enhancing understanding of their gamma-ray production.

Contribution

It provides the first comprehensive X-ray analysis of a complete sample of misaligned AGNs with GeV association, highlighting differences in accretion and emission processes.

Findings

FRIIs have higher accretion rates than FRIs.

Broad Line Regions are more active in high accretion rate objects.

External Compton is dominant in FRIIs, Synchrotron Self Compton in FRIs.

Abstract

The Fermi-LAT satellite has recently discovered a small group of radio galaxies and steep spectrum radio sources: the misaligned AGNs (MAGNs) sample. We present the X-ray analysis of all the sources of this sample (7 FRIs and 3 FRIIs) with a firm GeV association. This study supports the idea that FRIIs host more efficient accretion mechanisms (m_dot >0.1) than FRIs (m_dot <0.003). Furthermore, in objects with high accretion rates the Broad Line Regions appear to be very active zones where, in addition to optical lines, the fluorescence iron Kalpha feature at 6.4 keV is also produced. It seems that the FRII jets propagate in an environment very rich in photons, explaining, at least at zeroth order, why the External Compton is the preferred mechanism to produce gamma-rays. In FRIs, where also the iron line is difficult to be detected, the paucity of photons in the circumnuclear ambient seems to favor the Synchrotron Self Compton process.