4 research outputs found
A Nearby Repeating Fast Radio Burst in the Direction of M81
We report on the discovery of FRB 20200120E, a repeating fast radio burst
(FRB) with low dispersion measure (DM), detected by the Canadian Hydrogen
Intensity Mapping Experiment (CHIME)/FRB project. The source DM of 87.82 pc
cm is the lowest recorded from an FRB to date, yet is significantly
higher than the maximum expected from the Milky Way interstellar medium in this
direction (~ 50 pc cm). We have detected three bursts and one candidate
burst from the source over the period 2020 January-November. The baseband
voltage data for the event on 2020 January 20 enabled a sky localization of the
source to within 14 sq. arcmin (90% confidence). The FRB localization
is close to M81, a spiral galaxy at a distance of 3.6 Mpc. The FRB appears on
the outskirts of M81 (projected offset 20 kpc) but well inside its
extended HI and thick disks. We empirically estimate the probability of chance
coincidence with M81 to be . However, we cannot reject a Milky Way
halo origin for the FRB. Within the FRB localization region, we find several
interesting cataloged M81 sources and a radio point source detected in the Very
Large Array Sky Survey (VLASS). We searched for prompt X-ray counterparts in
Swift/BAT and Fermi/GBM data, and for two of the FRB 20200120E bursts, we rule
out coincident SGR 180620-like X-ray bursts. Due to the proximity of FRB
20200120E, future follow-up for prompt multi-wavelength counterparts and
sub-arcsecond localization could be constraining of proposed FRB models
No Evidence for Galactic Latitude Dependence of the Fast Radio Burst Sky Distribution
Abstract
We investigate whether the sky rate of fast radio bursts (FRBs) depends on Galactic latitude using the first catalog of FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project. We first select CHIME/FRB events above a specified sensitivity threshold in consideration of the radiometer equation, and then we compare these detections with the expected cumulative time-weighted exposure using Anderson–Darling and Kolmogorov–Smirnov tests. These tests are consistent with the null hypothesis that FRBs are distributed without Galactic latitude dependence (p-values distributed from 0.05 to 0.99, depending on completeness threshold). Additionally, we compare rates in intermediate latitudes (∣b∣ < 15°) with high latitudes using a Bayesian framework, treating the question as a biased coin-flipping experiment–again for a range of completeness thresholds. In these tests the isotropic model is significantly favored (Bayes factors ranging from 3.3 to 14.2). Our results are consistent with FRBs originating from an isotropic population of extragalactic sources.</jats:p