Supernovae Kicks in hierarchical triple systems

Abstract

Most massive stars, if not all, are in binary configuration or higher multiples. These massive stars undergo supernova explosions and end their lives as either black holes or neutron stars. Recent observations have suggested that neutron stars and perhaps even black holes receive large velocity kicks at birth. Such natal kicks and the sudden mass loss can significantly alter the orbital configuration of the system. Here we derive general analytical expressions that describe the effects of natal kicks in binaries on hierarchical triple systems. We explore several proof-of-concept applications such as black hole and neutron stars binaries and X-ray binaries with either stellar or Supermassive Black Hole (SMBH) companions on a wide orbit. Kicks can disrupt the hierarchical configuration, although it is harder to escape the potential well of an SMBH. Some binary systems do escape the SMBH system resulting in hyper-velocity binary system. Furthermore, kicks can result in increasing or decreasing the orbital separations. Decreasing the orbital separation may have significant consequences in these astrophysical systems. For example, shrinking the separation post-supernova kick can lead to the shrinking of an inner compact binary that then may merge via Gravitational Wave (GW) emission. This process yields a supernova that is shortly followed by a possible GW-LIGO event. Interestingly, we find that the natal kick can result in shrinking the outer orbit, and the binary may cross the tertiary Roche limit, breaking up the inner binary. Thus, in the case of SMBH companion, this process can lead to either a tidal disruption event or a GW-LISA detection event (Extreme Mass ratio inspiral, EMRI) with a supernova precursor.

Can supernova kicks trigger EMRIs in the Galactic Centre?

“…The S-stars, representative of the TE case, display a broader distribution of times compared to the CW disc (which is representative of the GE cases), especially if the L background population induces NRR. The typical inspiral times reported here are compatible to what found by Lu & Naoz (2019), addressing SN kicks in binary stars about a Milky-Way-like SMBH. Lu & Naoz (2019) also suggest GW events can occur over a time-scale as short as a few minutes after the SN, but they do not distinguish between proper EMRIs and direct plunges.…”

“…The typical inspiral times reported here are compatible to what found by Lu & Naoz (2019), addressing SN kicks in binary stars about a Milky-Way-like SMBH. Lu & Naoz (2019) also suggest GW events can occur over a time-scale as short as a few minutes after the SN, but they do not distinguish between proper EMRIs and direct plunges. Figure 8 shows the initial versus the final specific binding energy and specific angular momentum magnitude of SN-EMRIs (data points) and of all the COs that remain bound to the SMBH (contours) in two representative cases.…”

Fast radio burst repeaters produced via Kozai-Lidov feeding of neutron stars in binary systems

“…The companion can be a main sequence star, have already transformed into a white dwarf, or become a neutron star or a black hole following a second supernova explosion (Portegies Zwart & Verbunt 1996;Lorimer 2008). However, in most scenarios, the explosion or the kick experienced by the neutron star at birth disrupts the binary system (Hansen & Phinney 1997;Lu & Naoz 2019).…”

Neutron Star–Black Hole Mergers from Gravitational-wave Captures

“…Aside from GW captures, GN can be the site of binary mergers induced by interactions with the SMBH (e.g., Antonini & Perets 2012;Naoz 2016;Stephan et al 2016Stephan et al , 2019Hoang et al 2018), via the Eccentric Kozai-Lidov Mechanism (EKL Kozai 1962;Lidov 1962;Naoz 2016). Recently Lu & Naoz (2019) suggested that supernova natal kicks can tend to shrink the post supernova separation. Moreover they showed that these systems are more likely to stay in a triple configuration near an SMBH.…”