On The Origin of Supernova-Less Long Gamma Ray Bursts

TL;DR

This paper investigates the origins of long gamma-ray bursts without associated supernovae, proposing that they originate from relativistic jets launched during neutron star phase transitions or mergers, with implications for their distribution across redshifts.

Contribution

It introduces a model explaining SN-less long GRBs via relativistic jets from neutron star phase transitions or mergers, highlighting the role of high mass X-ray binaries.

Findings

X-ray afterglows are consistent with jets from neutron star events.

High redshift GRBs suggest neutron star phase transitions in HMXBs.

Fraction of SN-less GRBs is comparable to those with supernovae.

Abstract

The fraction of long duration gamma ray bursts (GRBs) without an associated bright supernovae (SNe) at small redshifts $(z<0.15)$ is comparable to that of GRBs associated with SNe. We show, that their X-ray afterglow and the X-ray afterglow of most of the nearby $(z<1)$ GRBs without a confirmed association with SNe, are well reproduced by the launch of highly relativistic jets in the SN-less birth of millisecond pulsars in neutron star mergers or through phase transition of neutron stars to quark stars following mass accretion in compact binaries. Such a large fraction of GRBs with pulsar-like afterglow that extends to very large redshifts $(z>4)$, however, favors phase transition of neutron stars to quark stars in high mass X-ray binaries (HMXBs), rather than merger of neutron stars, as the origin of SN-less GRBs.