Fast Radio Bursts from Activity of Neutron Stars Newborn in BNS Mergers: Offset, Birth Rate, and Observational Properties

Abstract

Young neutron stars (NSs) born in core-collapse explosions are promising candidates for the central engines of fast radio bursts (FRBs), since the first localized repeating burst FRB 121102 happens in a star forming dwarf galaxy, which is similar to the host galaxies of superluminous supernovae (SLSNe) and long gamma-ray bursts (LGRBs). However, FRB 180924 and FRB 190523 are localized to massive galaxies with low rates of star formation, compared with the host of FRB 121102. Meanwhile, the offsets between the bursts and host centers are about 4 kpc and 29 kpc for FRB 180924 and FRB 190523, respectively. These properties of hosts are similar to short gamma-ray bursts (SGRBs), which are produced by mergers of binary neutron star (BNS) or neutron star-black hole (NS-BH). Therefore, the NSs powering FRBs may be formed in BNS mergers. In this paper, we study the BNS merger rates, merger times, and predict their most likely merger locations for different types of host galaxies using population synthesis method. We find that the BNS merger channel is consistent with the recently reported offsets of FRB 180924 and FRB 190523. The offset distribution of short GRBs is well reproduced by population synthesis using galaxy model which is similar to GRB hosts. The event rate of FRBs (including non-repeating and repeating), is larger than those of BNS merger and short GRBs, which requires a large fraction of observed FRBs emitting several bursts. Using curvature radiation by bunches in NS magnetospheres, we also predict the observational properties of FRBs from BNS mergers, including the dispersion measure, and rotation measure. At late times (t ≥ 1yr), the contribution to dispersion measure and rotation measure from BNS merger ejecta could be neglected.

Probing the Universe with Fast Radio Bursts

“…Bhandari et al [165] and Heintz et al [166] agreed that compact merger events (WD-WD, NS-NS mergers), accretion-induced WD collapse and CCSNe seem to be plausible mechanisms for the FRBs localised by ASKAP and that the galaxies hosting LGRBs (faint, star-forming galaxies) are less likely to be common hosts for FRBs. This is also consistent with an independent study which compared the host galaxy properties of FRBs with those of stellar transients such as Type Ib/Ic supernovae (SN Ibc), Type II supernovae (SN II), Type Ia supernovae in addition to long and short GRBs [167] and work of Wang et al [168] which showed that the compact mergers can account for the observed offset distribution of localised FRBs.…”

A unified picture of Galactic and cosmological fast radio bursts

“…Metzger, Berger & Margalit 2017), or NS mergers (e.g. Margalit, Berger & Metzger 2019;Wang et al 2020a), so that they have relatively short (e.g. millisecond) periods at births (Usov 1992;Zhang & Mészáros 2001;Metzger et al 2011).…”

On the FRB luminosity function – – II. Event rate density

“…One possible scenario would be to invoke an NS-NS post-merger stable magnetar that can survive the merger (e.g. Zhang & Mészáros 2001;Metzger et al 2008;Bucciantini et al 2012;Rezzolla & Kumar 2015;Margalit et al 2019;Wang et al 2020). However, this requires a stiff NS equation of state and small masses in the NS-NS merger systems.…”