A 2.9 hr Periodic Radio Transient with an Optical Counterpart
N. Hurley‐Walker, S. J. McSweeney, Arash Bahramian, N. Rea, Christopher Horvath, S. Buchner, A. Williams, Bradley W. Meyers, Jay Strader, E. Aydi, Ryan Urquhart, Laura Chomiuk, Timothy J. Galvin, F. Coti Zelati, M. Bailes
Abstract
Abstract We present a long-period radio transient (GLEAM-X J0704−37) discovered to have an optical counterpart, consistent with a cool main-sequence star of spectral type M3. The radio periodicity occurs at the longest period yet found, 2.9 hr, and was discovered in archival low-frequency data from the Murchison Widefield Array. High time resolution observations from MeerKAT show that pulsations from the source display complex microstructure and high linear polarisation, suggesting a pulsar-like emission mechanism occurring due to strong, ordered magnetic fields. The timing residuals, measured over more than a decade, show tentative evidence of a ∼6 yr modulation. The high Galactic latitude of the system and the M-dwarf star excludes a magnetar interpretation, suggesting a more likely M-dwarf/white dwarf binary scenario for this system.