Speaker: Alessandro Peca (Universidad Diego Portales, Santiago, Chile)
Active galactic nuclei (AGN) are powered by accretion onto supermassive black holes and are among the most luminous persistent sources in the Universe. Despite decades of study, however, a fundamental question remains open: how is gas transported from the host galaxy down to the immediate vicinity of the black hole?
X-ray observations provide a unique view of this environment, probing the innermost regions of AGN and revealing the physical state, geometry, and dynamics of highly ionized gas. In this talk, I will introduce the basic X-ray properties of AGN and discuss how X-ray spectroscopy can be used to trace obscuration, accretion flows, and powerful winds close to the central engine.
I will then focus on the feeding side of the problem and present recent evidence for a highly ionized, relativistic inflow observed in the X-ray spectrum of an AGN. I will discuss its possible location, physical interpretation, and implications for the way matter may be supplied to supermassive black holes.