A polarized fast radio burst at low Galactic latitude

Abstract

We report on the discovery of a new fast radio burst, FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6±0.8 pc cm −3 , a pulse duration of 2.8 +1.2 −0.5 ms, and a measured peak flux density assuming the burst was at beam center of 0.7 +0.2 −0.1 Jy. The FRB originated at a Galactic longitude and latitude of 24.66 • , 5.28 • , 25 degrees away from the Galactic Center. The burst was found to be 43±5% linearly polarized with a rotation measure (RM) in the range −9 < RM < 12 rad m −2 (95% confidence level), consistent with zero. The burst was followed-up with 11 telescopes to search for radio, optical, X-ray, γ-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 hours of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.

On the FRB luminosity function – – II. Event rate density

“…With the exception of t svy , N and Ω, which are new additions, these parameters had been discussed in L18. The data we use come from a variety of pulsar surveys carried out around 1 GHz: the Parkes Magellanic Cloud Pulsar Survey ((PKS-MC; Lorimer et al 2007;Zhang et al 2019); the High Time Resolution Universe (HTRU; Thornton et al 2013;Champion et al 2016;Ravi et al 2015;Petroff et al 2015aPetroff et al , 2017; the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB; Keane et al 2016;Ravi et al 2016;Bhandari et al 2018a), Pulsar Arecibo L-band Feed Array (PALFA; Spitler et al 2014); Green Bank Telescope Intensity Mapping (GBTIM; Masui et al 2015); UTMOST Southern Sky (UTMOST-SS; Caleb et al 2017)) and the Commensal Real-time ASKAP Fast Transients (CRAFT; Shannon et al 2018). We do not include the CHIME discoveries, since we focus on the FRB LF whose radio emission is around 1 GHz.…”

Repeating Fast Radio Bursts from Magnetars with Low Magnetospheric Twist

“…The striking similarity between the fluence and recurrence rate phenomenology of magnetar short bursts and FRB 121102 pulses motivates us to consider a model where repeating FRBs are generated in magnetospheres of (some) magnetars experiencing short bursts. Additional arguments in favor of such an explanation would be the fact that highly magnetized NSs -pulsars and some magnetars -do exhibit coherent radio emission and the high magnetic fields of NSs would help to explain the high polarization seen in the pulses of FRB 121102 (some other FRBs also exhibit high linear polarization e.g., Masui et al 2015;Petroff et al 2017;Caleb et al 2018) -such linear polarization is suggestive of either generation in or natural eigenmode propagation within strong and ordered magnetic fields (e.g., Melrose 2017).…”

Commensal discovery of four fast radio bursts during Parkes Pulsar Timing Array observations

“…Observations with Swift would have become possible starting on 2018-02-18, about 11 days after the FRB detection. We refrained from performing such late-time observations, already attempted in several other FRB follow-ups (e.g., Petroff et al 2015aPetroff et al , 2017 which were unsuccessful.…”