# A polarized fast radio burst at low Galactic latitude

## TL;DR

This paper reports the discovery of a new fast radio burst (FRB 150215) at low Galactic latitude, characterized by low rotation measure and no associated transient emission, highlighting the diversity of FRB properties and their Galactic environment.

## Contribution

The paper presents the first detailed observation of an FRB at low Galactic latitude with low RM, expanding understanding of FRB properties in different Galactic environments.

## Key findings

- FRB 150215 has a dispersion measure of 1105.6 pc cm^{-3}.
- The burst shows 43% linear polarization with near-zero RM.
- No associated transient or repeating signals were detected in follow-up observations.

## 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$\pm$0.8 pc cm^{-3}, a pulse duration of 2.8^{+1.2}_{-0.5} ms, and a measured peak flux density assuming the burst was at beam center of 0.7^{+0.2}_{-0.1} Jy. The FRB originated at a Galactic longitude and latitude of 24.66^{\circ}, 5.28^{\circ}, 25 degrees away from the Galactic Center. The burst was found to be 43$\pm$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, gamma-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.