A bright, high rotation-measure FRB that skewers the M33 halo

Abstract

We report the detection of a bright fast radio burst, FRB 191108, with Apertif on the Westerbork Synthesis Radio Telescope (WSRT). The interferometer allows us to localise the FRB to a narrow 5″ × 7′ ellipse by employing both multibeam information within the Apertif phased-array feed (PAF) beam pattern, and across different tied-array beams. The resulting sight line passes close to Local Group galaxy M33, with an impact parameter of only 18 kpc with respect to the core. It also traverses the much larger circumgalactic medium of M31, the Andromeda Galaxy. We find that the shared plasma of the Local Group galaxies could contribute ∼10% of its dispersion measure of 588 pc cm−3. FRB 191108 has a Faraday rotation measure of +474 ± 3 rad m−2, which is too large to be explained by either the Milky Way or the intergalactic medium. Based on the more moderate RMs of other extragalactic sources that traverse the halo of M33, we conclude that the dense magnetised plasma resides in the host galaxy. The FRB exhibits frequency structure on two scales, one that is consistent with quenched Galactic scintillation and broader spectral structure with Δν ≈ 40 MHz. If the latter is due to scattering in the shared M33/M31 CGM, our results constrain the Local Group plasma environment. We found no accompanying persistent radio sources in the Apertif imaging survey data.

Chromatic periodic activity down to 120 megahertz in a fast radio burst

“…Single receivers have been replaced by phased array feeds (PAFs), increasing its field of view to ∼8.7 square degrees 31,32 . Apertif can work in time-domain observing mode to search for new FRBs 33 and follow-up known ones 34 using eight of the WSRT dishes. This capability is provided by a new backend, ARTS (the Apertif Radio Transient System 11,35,36 ).…”

Wide field beamformed observation with MeerKAT

“…The APERTIF survey (Adams and van Leeuwen, 2019) with the Westerbork Synthesis Radio Telescope (WSRT) and the Australian Square Kilometre Array Pathfinder (ASKAP, Johnston et al, 2008) are the first two interferometers to be equipped with the PAFs to increase their FoV. This has lead to further FRB discoveries (Bannister et al, 2017;Connor et al, 2020). The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has led the field in the hunt for FRBs.…”

Probing the Universe with Fast Radio Bursts

“…Fast radio bursts (FRBs) are millisecond-duration pulses of radio emission that originate at cosmological distances. Around 140 FRBs have been published to date, with the Parkes radio telescope [1][2][3][4], the Arecibo telescope [5], the Green Bank telescope [6,7], the UTMOST telescope [4,8,9], the Australian Square Kilometre Array Pathfinder (ASKAP) [4,[10][11][12][13][14], the Canadian Hydrogen Intensity Mapping Experiment (CHIME) [15][16][17][18], the Deep Synoptic Array (DSA-10) [19], the Apertif telescope [20], the FAST telescope [21,22] and the Karl G. Jansky Very Large Array (VLA) [23] all contributing. The bursts are indicative of extremely luminous coherent radiation of brightness temperature T b ∼ 10 35 K, whose 0.1-10 ms duration confines their emission regions to a radius less than 30-3000 km.…”