Dynamics of Dual Massive Black Hole Systems Formation in Cosmological Simulations

Abstract

Due to hierarchical evolution of galaxies and fact that almost all massive galaxies have supermassive black hole (SMBH) in their center, galaxy mergers lead to formation of dual SMBH systems or supermassive black hole binaries (SMBHB). In order to better understand how properties of SMBHBs depend on properties of merging galaxies, we researched these systems, circumstances of their forming and activity using the results from cosmological simulation IllustrisTNG300. We found that major mergers are the main reason for formation of dual AGNs with tendency to form more luminous AGNs. Large gas abundance is necessary for SMBH activity but its presence is not enough. Influence of redshift, SMBH mass ratio and total mass of the galaxy is consequence of dependence of merger type (whether the merger is minor or major). Number density of dual AGN in IllustrisTNG300 on redshift z=2 is 9.13 × 10−6 Mpc−3