Non-conservative Mass Transfer in the Neutron Star Stripping Model

TL;DR

This paper models long-term stable mass transfer in neutron star binaries, incorporating non-conservative effects, which extends transfer duration and explains observed delays and features in gamma-ray burst signals.

Contribution

It introduces the first detailed calculation of non-conservative mass transfer in neutron star stripping, revealing longer stability periods and explaining multimessenger event timing.

Findings

Stable mass transfer duration increased to a few seconds.

The delay between gravitational wave and gamma-ray burst is naturally explained.

Envelope interaction may account for features in gamma-ray burst light curves.

Abstract

The process of long-term stable mass transfer (or stripping) in a close neutron star binary system is possible at a sufficiently large initial asymmetry of the component masses. At the final stage of the evolution of such systems, the low-mass neutron star fills its Roche lobe, whereupon its mass is gradually transferred to the more massive component. At a certain point, the stability of the mass transfer is lost, causing the minimum-mass neutron star to explode. In the present stripping calculations, the effect of non-conservative mass transfer has been taken into account for the first time, resulting in an increase in the duration of stable mass transfer from a few tenths of a second to a few seconds. This allows the time delay of 1.7 s between the loss of the gravitational-wave signal and the detection of the gamma-ray burst from the multimessenger event GW170817-GRB170817A to be naturally explained. The interaction of the envelope of the exploded minimum-mass neutron star with the matter ejected during non-conservative mass transfer may explain two episodes in the light curve of this gamma-ray burst.