GBT22A-462

Timing a New Spider MSP with a Giant Companion

Abstract

We have discovered a new low-mass X-ray binary located within the error ellipse of the Fermi-LAT gamma-ray source 4FGL J1947.6-1121. The presumed X-ray and optical counterpart shows emission consistent with an emerging class of binary: a millisecond pulsar (MSP) being orbited by a giant companion in a wide orbit. We recently detected the radio MSP in a pointed GBT search, just after the 2022B GBT Proposal Call, motivating this DDT request. The discovery of this pulsar confirms the existence of a subclass of long-period MSP binaries with giant companions--the plausible progenitors for typical MSP-white dwarf binaries observed in the field. Here we request 3 x 2.0 hr blocks on the GBT to time the radio MSP, offering the best chance for measuring the projected semi-major axis of the pulsar orbit and allowing us to fully solve for the component masses in the binary, thereby establishing a firm evolutionary link between the bulk of the MSP binary population and their precursors.

Investigators

Name	Institution
Paul Ray	Naval Research Laboratory
Samuel Swihart *	Michigan State University; Naval Research Laboratory

* indicates the PI