Rolling down from the 30 keV peak: Modelling the hard X-ray and γ-ray backgrounds

Abstract

We will briefly discuss the importance of sensitive X-ray observations above a few tens of keV for a better understanding of the physical mechanisms associated to the Supermassive Black Hole primary emission in both radio quiet and radio loud AGN and to the cosmological evolution of the most obscured sources.

On the two main classes of active galactic nuclei

“…The most striking difference is in the hard X-ray to γ-ray band: while many (likely all: but see below) RL sources emit all the way up to GeV (2.4 × 10 23 Hz), and sometimes TeV (2.4 × 10 26 Hz), energies, nearby (RQ) bright Seyfert galaxies have a sharp cut-off at energies 1 MeV (e.g., Malizia et al, 2014). This cut-off has to apply to the whole RQ AGN population in order not to violate the X-ray background above this energies (Comastri et al, 2005). Moreover, no RQ AGN has ever been detected in γ-rays (Ackermann et al, 2012a) with the exception of NGC 1068 and NGC 4945, two Seyfert 2 galaxies in which the γ-ray emission is thought to be related to their starburst component (Ackermann et al, 2012b).…”