Evolution of Low-Mass X-ray Binaries: the Effect of Donor Evaporation

Understand

Millisecond pulsars (MSPs) are thought to originate from low-mass X-ray binaries (LMXBs).

• The discovery of eclipsing radio MSPs including redbacks and black widows indicates that evaporation of the donor star by the MSP's irradiation takes place during the LMXB evolution.
• In this work, we investigate the effect of donor evaporation on the secular evolution of LMXBs, considering different evaporation efficiencies and related angular momentum loss.
• We find that for widening LMXBs, the donor star leaves a less massive white dwarf than without evaporation; for contracting systems, evaporation can speed up the evolution, resulting in dynamically unstable mass transfer and possibly the formation of isolated MSPs.