Signatures from clusters of stellar black holes in supercritical AGNs

LEANDRO ABAROA; GUSTAVO E. ROMERO

Praga

Exposición; Seminario en la Academica de Ciencias de República Checa; 2023

Academia de Ciencias de República Checa

Active galactic nuclei (AGNs) are powered by accretion onto supermassiveblack holes (SMBHs) with masses in the range 10^6—10^9 Msun. These SMBHsare fed by accretion disks radiating from the IR/optical bands to theX-rays. Different types of objects can orbit the SMBHs, includingmassive stars, neutron stars, clouds from broad- and narrow-lineregions, and X-ray binaries. Isolated stellar mass black holes (BHs of~10 Msun) should also be present in large numbers within the centralparsec of the galaxies. These BHs are expected to form a cluster aroundthe SMBH as a result of the enhanced star formation rate in the innergalaxy and black hole migration caused by gravitational dynamicalfriction. In this talk, we will explore the possibility of detectingelectromagnetic signatures of a central cluster of BHs in asupercritical AGN, that is, an AGN where the accretion rate onto thecentral SMBH is greater than the Eddington rate. In these supercriticalnuclei, the accretion disk launches powerful winds that interact withthe objects orbiting the SMBH. Isolated BHs can capture matter from thisdense wind, leading to the formation of small accretion disks aroundthem. If jets are produced in these non-stellar microquasars, they mightbe sites of particle acceleration up to relativistic energies. Theseparticles, in turn, should cool by different radiative processes.Therefore, the wind of the SMBH can eventually illuminate the BHsthrough the production of nonthermal radiation.