Huntsman may need to be irradiated

Abstract

Millisecond pulsars are rapidly rotating neutron stars, and it is now widely accepted that their extremely short rotation periods result from the accretion of material from a companion star. Binary evolution theory predicts that millisecond pulsars can have various types of companion stars. However, in observations, binary pulsars with giant companions, referred to as ``huntsman pulsars'', are extremely rare. Following the initial discovery of the first huntsman pulsar, 1FGL J1417.7-4407, a second huntsman millisecond pulsar binary, PSR J1947-1120, has been recently reported approximately a decade later. In this paper, we model the formation and evolution of two huntsman pulsars. Our model with the irradiation effect can explain the observed properties of huntsman pulsar binaries and suggests that if the irradiation effect is considered, the companion star may be a normal red giant star, rather than just a red bump star.