Gamma-Ray and X-Ray Observations of the Periodic-repeater FRB 180916 during Active Phases
Abstract
FRB 180916 is a most intriguing source capable of producing repeating fast radio bursts with a periodic 16.3 day temporal pattern. The source is well positioned in a star-forming region in the outskirts of a nearby galaxy at 150 Mpc distance. In this Letter we report on the X-ray and γ-ray observations of FRB 180916 obtained by AGILE and Swift. We focused especially on the recurrent 5 day time intervals of enhanced radio bursting. In particular, we report on the results obtained in the time intervals 2020 February 3-8, 2020 February 25, 2020 March 5-10, and 2020 March 22-28 during a multiwavelength campaign involving high-energy and radio observations of FRB 180916. We also searched for temporal coincidences at millisecond timescales between the 32 known radio bursts of FRB 180916 and X-ray and MeV events detectable by AGILE. We do not detect any simultaneous event or any extended X-ray and γ-ray emission on timescales of hours/days/weeks. Our cumulative X-ray (0.3-10 keV) flux upper limit of 5 × 10-14 erg cm-2 s-1 (obtained during 5 day active intervals from several 1-2 ks integrations) translates into an isotropic luminosity upper limit of LX,UL ∼ 1.5 × 1041 erg s-1. Deep γ-ray observations above 100 MeV over a many-year timescale provide an average luminosity upper limit one order of magnitude larger. These results provide the so-far most stringent upper limits on high-energy emission from the FRB 180916 source. Our results constrain the dissipation of magnetic energy from a magnetar-like source of radius Rm, internal magnetic field Bm, and dissipation timescale τd to satisfy the relation ${R}_{m,6}^{3}\,{B}_{m,16}^{2}\,{\tau }_{d,8}^{-1}\lesssim 1$ , where Rm,6 is Rm in units of 106 cm, Bm,16 is Bm in units of 1016 G, and τd,8 in units of 108 s.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2020
- DOI:
- 10.3847/2041-8213/ab86b1
- arXiv:
- arXiv:2004.03676
- Bibcode:
- 2020ApJ...893L..42T
- Keywords:
-
- Gamma-ray astronomy;
- X-ray astronomy;
- Radio bursts;
- Radio transient sources;
- Gamma-ray transient sources;
- 628;
- 1810;
- 1339;
- 2008;
- 1853;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication by the Astrophysical Journal Letters on April 5, 2020