paper

The abundances and properties of Dual AGN and their host galaxies in the EAGLE simulations

arXiv:1805.01479 · doi:10.1093/mnras/sty3251

Abstract

We look into the abundance of Dual AGN in the largest hydrodynamical simulation from the EAGLE project. We define a Dual AGN as two active black holes (BHs) with a separation below 30 kpc. We find that only 1 per cent of AGN with $\LhX\geq 10^{42}\ergs$ are part of a Dual AGN system at . During the evolution of a typical binary BH system, the rapid variability of the hard X-ray luminosity on Myr time-scales severely limits the detectability of Dual AGN. To quantify this effect, we calculate a probability of detection, , where is the time in which the two black holes are separated at distances below 30 kpc and , the time that both AGN are visible (e.g. when both AGN have $\LhX\geq 10^{42}\ergs$) in this period. We find that the average fraction of visible Dual systems is 3 per cent. The visible Dual AGN distribution as a function of BH separation presents a pronounced peak at kpc that can be understood as a result of the rapid orbital decay of the host galaxies after their first encounter. We also find that per cent of the host galaxies have recently undergone or are undergoing a merger with stellar mass ratio . Finally, we find that the fraction of visible Dual AGN increases with redshift as found in observations.

arXiv comment10 pages, 8 figures, accepted to MNRAS. It includes a new section of discussion with a new figure

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