Electromagnetic counterparts from counter-rotating relativistic kicked discs

Abstract

We show the results of two dimensional general relativistic inviscid and isothermal hydrodynamical simulations comparing the behavior of co-rotating (with respect to the black hole rotation) and counter-rotating circumbinary quasi-Keplerian discs in the post merger phase of a supermassive binary black hole system. While confirming the spiral shock generation within the disc due to the combined effects of mass loss and recoil velocity of the black hole, we find that the maximum luminosity of counter-rotating discs is a factor ∼ (2 − 12) higher than in the co-rotating case, depending on the spin of the black hole. On the other hand, the luminosity peak happens ∼ 10 days later with respect to the co-rotating case. Although the global dynamics of counter-rotating discs in the post merger phase of a merging event is very similar to that for co-rotating discs, an important difference has been found. In fact, increasing the spin of the central black hole produces more luminous co-rotating discs while less luminous counter-rotating ones.

Electromagnetic Counterparts to Massive Black Hole Mergers

“…In contrast, for a kick oriented perpendicularly to the disk, the resulting concentric density enhancements are weaker and delayed to potentially 1 year after the merger. This general picture of recoil-induced disk perturbations, and the dependence on kick direction, has been substantiated by later studies using full hydrodynamics simulations (Figure 29; Megevand et al, 2009;Rossi et al, 2010;Corrales et al, 2010;Zanotti et al, 2010;Zanotti, 2012;Ponce et al, 2012). Rossi et al (2010), Corrales et al (2010), andZanotti et al (2010) all reach similar conclusions regarding the luminosity and timescale of a recoil-induced afterglow.…”

“…Thus, until viscous effects can return the disk to its pre-merger radius, which can take several hundred M of time (amounting to days for a 10 8 M central black hole), the efficiency of emission and hence the luminosity will be less than it was pre-merger. Subsequent studies have confirmed this basic picture (Megevand et al, 2009;Corrales et al, 2010;Anderson et al, 2010;Rosotti et al, 2012;Zanotti, 2012). Whether this effect is detectable depends on variables such as the primary band of emission and the extinction of the center of the host galaxy.…”

Simulations of recoiling black holes: adaptive mesh refinement and radiative transfer

“…Several authors have discussed the dynamics and related emission from a circumbinary disc with the recoiling central black hole in the post-merger phase (e.g. Lippai et al 2008;Megevand et al 2009;Anderson et al 2010;Corrales et al 2010;Rossi et al 2010;Zanotti et al 2010;Ponce et al 2012;Zanotti 2012;Gold et al 2014b). …”

“…This is indeed a well-explored area of research, and several studies have investigated the 2D dynamics resulting from a recoiling black hole (e.g. Corrales et al 2010;Zanotti et al 2010;Zanotti 2012) and 3D simulations (e.g. Lippai et al 2008, Megevand et al 2009, Anderson et al 2010, Ponce et al 2012.…”

Astrophysics of super-massive black hole mergers

“…These effects lead to caustics forming in the perturbed disk, in turn leading to shock heating and potentially both prompt and long-lived EM afterglows [184,165,214,55,268,197,213,269]. Any spin alignment would be critically important for both the character of the prompt EM counterpart, as well as the recoil velocity [159,23].…”