Thermal Timescale Mass Transfer Rates in Intermediate-Mass X-ray Binaries

TL;DR

This paper systematically investigates thermal timescale mass transfer in intermediate-mass X-ray binaries, revealing that actual transfer rates are significantly lower than traditional estimates, which impacts understanding of binary evolution.

Contribution

It provides a comprehensive calculation of binary evolution sequences, showing that mass transfer rates are about four times lower than previously estimated in such systems.

Findings

Mass transfer rates are on average four times lower than traditional estimates.

The study uses detailed binary evolution calculations with various initial conditions.

Results suggest revisions are needed for models of binary evolution involving intermediate-mass donors.

Abstract

Thermal timescale mass transfer generally occurs in close binaries where the donor star is more massive than the accreting star. The mass transfer rates are usually estimated in terms of the Kelvin-Helmholtz timescale of the donor star. But recent investigations indicate that this method may overestimate the real mass transfer rates in accreting white dwarf or neutron star binary systems. We have systematically investigated the thermal-timescale mass transfer processes in intermediate-mass X-ray binaries, by calculating binary evolution sequences with various initial donor masses and orbital periods. From the calculated results we find that on average the mass transfer rates are lower than traditional estimates by a factor of $\sim 4$.