Search

We model the formation of black hole–neutron star (BH–NS) binaries via dynamical interactions in globular clusters. We find that in dense, massive clusters, 16–61 per cent of the BH–NS binaries formed by interactions with existing BH binaries will undergo mergers driven by the emission of gravitational radiation. If the BHs are retained by the cluster after merging with an NS, the BHs acquire subsequent NS companions and undergo several mergers. Thus, the merger rate depends critically upon whether or not the BH is retained by the cluster after the merger. Results from numerical relativity suggest that kick imparted to a ∼7 M⊙ BH after it merges with an NS will greatly exceed the cluster's escape velocity. In this case, the models suggest that the majority of BH–NS mergers in globular clusters occur within 4 Gyr of the cluster's formation and would be unobservable by Advanced LIGO. For more massive BHs, on the other hand, the post-merger kick is suppressed and the BH is retained. Models with 35 M⊙ BHs predict Advanced LIGO detection rates in the range 0.04–0.7 yr−1. On the pessimistic end of this range, BH–NS mergers resulting from binary–single star interactions in globular clusters could account for an interesting fraction of all BH–NS mergers. On the optimistic end, this channel may dominate the rate of detectable BH– NS mergers. [ABSTRACT FROM AUTHOR]

Abstract: Detection of electromagnetic (EM) counterparts of pre-coalescence binaries has very important implications for our understanding of the evolution of these systems as well as the associated accretion physics. In addition, a combination of EM and gravitational wave signatures observed from coalescing supermassive black hole binaries (SBHBs) would provide independent measurements of redshift and luminosity distance, thus allowing for high precision cosmological measurements. However, a statistically significant sample of these objects is yet to be attained and finding them observationally has proven to be a difficult task. Here we discuss existing observational evidence and how further advancements in the theoretical understanding of observational signatures of SBHBs before and after the coalescence can help in future searches. [Copyright &y& Elsevier]