Lunch talk on Sep. 14, 2020

On the Formation of Eccentric Millisecond Pulsar Binaries

Speaker:Qin Han (NJU)

Venue:Video conference

Time:12:30 PM, Monday, Sep. 14, 2020

Abstract:

Binary millisecond pulsars (MSPs) are believed to have descended from low-mass X-ray systems (LMXBs) that have experienced substantial mass transfer and tidal circularisation, therefore should have eccentricities less than 0.01. However, five MSPs with eccentricities of approximately 0.03-0.2 are observed in recent years with similar masses and orbital periods, this demands a reexamination of the conventional picture. Three models have been proposed thus far based on accretion induced collapse, neutron star-strange star transition or circumbinary disks, respectively. The constraints predicted by these models are not entirely consistent with observation and subjected to various uncertainties. We propose a new model based on the thermonuclear flashes of proto-white dwarfs (proto-WDs) assuming that the flashes leads to asymmetrical mass ejection from the shell region and imparted a mild kick on the proto-WD. By simulating populations of MSP binaries subjected to kick(s) and investigate their orbital properties, we show that two scenarios of our WD-kick model that can reproduce the observed eccentric MSPs, either with a single WD-kick of a relatively large magnitude, or with multiple kicks of a small magnitude.

Report PPT:SWIFAR_Qin Han.pdf