One of the fundamental open questions in our understanding of Active Galactic
Nuclei (AGN) is the difference between radio-loud (RL) and radio-quiet
(RQ) objects. While the ultimate source of power is thought to be the
same in both AGN classes (i.e., accretion of gas onto a supermassive
black hole), the origin of the RL/RQ AGN dichotomy is still unknown.
The X-ray Advantage:
X-rays are one of the tools by which we can achieve progress in our
understanding of the nature of accretion in AGN and look for
differences in the structure of the accretion flows of RL and RQ AGNs.
This is because the X-rays originate in the innermost, hottest parts of
the accretion flow, and thanks to their high penetrating power, carry to us
features both in absorption and in emission which are diagnostic of the
conditions of the matter around the supermassive black hole.