Irradiation-Reduced Mass Accretion by Neutron Stars in X-Ray Binaries
Lorne Nelson (Bishop’s University)
April 25, 2019
Abstract: Very precise timing measurements of binary millisecond pulsars (bMSPs) have allowed us to conclude that neutron stars (NSs) have a wide range of masses spanning from at least 1.17 to 2.0 Msun. However, we still do not know the upper limit to the mass that can be accreted by a neutron star and why the mass-transfer process that leads to its spin-up is so non-conservative. In this talk I will briefly describe some of the evolutionary pathways that lead to the formation of recycled pulsars and, in particular, bMSPs. I will show that X-ray irradiation feedback during the accretion phase of the formation of bMSPs can cause quasi-periodic episodes of highly non-conservative mass transfer that strongly attenuate mass accretion by the NSs. This results in the formation of bMSPs with greatly reduced masses than would have otherwise been expected from fully conservative mass transfer and leads to a much more robust agreement with observations. Most importantly, we demonstrate that our model has very little impact on the long-term, secular-average evolution of the low/intermediate-mass X-ray binary systems that are the progenitors of bMSPs.