Constraining the Nature of the 18 min Periodic Radio Transient GLEAM-X J162759.5-523504.3 via Multiwavelength Observations and Magneto-thermal Simulations

Abstract We observed the periodic radio transient GLEAM-X J162759.5-523504.3 (GLEAM-X J1627) using Chandra X-ray Observatory for about 30 ks on 2022 January 22–23, simultaneously with observations from Murchison Widefield Array, MeerKAT, and Australia Telescope Compact Array. Its emission 18 min periodicity led source to be tentatively interpreted as an extreme magnetar or a peculiar highly magnetic white dwarf. The was not detected in 0.3–8 keV energy range 3 ? upper limit count rate of × 10 ?4 counts s ?1 . No during our either. Furthermore, we studied field around J1627 archival European Southern DECam Plane Survey data, well recent African Large observations. Many sources are present close position J1627, but only two within 2? uncertainty. Depending assumed spectral distribution, limits converted luminosity L X < 6.5 29 erg blackbody temperature kT = 0.3 keV, 9 power law photon index ? 2 (assuming 1.3 kpc distance). performed magneto-thermal simulations neutron stars considering crust- core-dominated configurations. Based multiband limits, conclude that (i) scenario, suggest should older than ?1 Myr, unless it has experienced fast cooling; (ii) dwarf can rule out most binary systems, hot sub-dwarf, isolated ( T ? 10.000 K), while cold is still compatible limits.