Upper Limits on Pulsed Radio Emission from Unseen Compact Objects in Six Galactic Stellar Binaries

TL;DR

This study searched for radio pulsars in six Galactic binary systems with potential neutron star primaries using the Green Bank Telescope but found no signals, setting upper limits on their radio luminosities.

Contribution

First comprehensive radio pulsar search in six binary systems with unseen primaries, establishing upper luminosity limits and constraining pulsar presence.

Findings

No astrophysical signals detected in the six systems.

Luminosity upper limits are comparable to or smaller than known binary pulsars.

Systems may lack pulsars, have unfavorably beaming, or contain very faint pulsars.

Abstract

We have conducted a search for radio pulsars in six Galactic stellar binary systems having unseen primary stars. All six systems have estimated primary masses in the range that could be consistent with neutron stars. We used the Green Bank Telescope at a center frequency of 350 MHz to search for dispersed periodicities and single pulses across a range of possible dispersion measures (DMs) and binary accelerations. No astrophysical signals were detected in our search. The estimated 400-MHz luminosity upper limits from the search are comparable to or smaller than the lowest values observed for almost all the known Galactic binary pulsars having cataloged 400 MHz radio luminosities. This implies that the systems we observed either do not harbor radio-emitting pulsars, contain pulsars that do not beam in our direction, or contain pulsars with luminosities that are significantly lower than this subset of the known Galactic binary pulsar population.