GBT21A-202

A Candidate Redback Millisecond Pulsar with an Unusually Massive Secondary

Abstract

We have discovered a new compact binary associated with 1FGL J0523--2528, one of the brightest remaining unidentified Fermi-LAT gamma-ray sources. Optical photometry, spectroscopy and X-ray observations have been used to show that the primary is a likely ~ 2 Msun neutron star and the secondary an unusually massive ~1.3 Msun. In addition, unlike nearly all known millisecond pulsar binaries, the system has an optically-measurable eccentricity of ~ 0.04. Here we request 12 hr of GBT time to detect the suspected radio pulsar primary, which will confirm the nature of the system and allow progress on understanding the properties and origin of this remarkable binary. These observations were approved as part of the 2020 DDT Special Call for filler time observations while the Green Bank Observatory was in its Infectious Disease Operating Status. However, only one (partially interrupted) block of our requested observations were observed, so we are requesting the same observations here in order to meet our project goals.

Investigators

Name	Institution
Samuel Swihart *	Michigan State University; Naval Research Laboratory
Maura McLaughlin	West Virginia University
Jay Strader	Michigan State University

* indicates the PI