Optical Counterparts to Black Widow Pulsars Discovered with Fermi LAT Space Telescope

Black widow pulsars are characterized as binaries where the secondary is a low mass star in a tight orbit with a millisecond pulsar. I report detections of the optical counterparts of two black widow pulsars discovered with radio follow-up observations of unidentified Fermi LAT sources. Orbital phase-matched photometric light curves are measured and characterized according to the standard black widow pulsar model whereby a millisecond pulsar heats the nearside of the companion object resulting in a brightening and a dimming over an orbital period. Measurements of these light curves allow for constraints to be placed on the system’s inclination and the temperature profile of the secondary and indicate features of the system that can be used to constrain the mass of the neutron stars. Such parameter measurements are necessary for answering outstanding question about the formation of millisecond pulsars and whether there is a evolutionary connection between low mass x-ray binaries, black widow pulsars, and isolated millisecond pulsars observed in the field.