The repeating Fast Radio Burst FRB 121102: Multi-wavelength observations and additional bursts

TL;DR

This paper presents multi-wavelength observations of the only known repeating FRB 121102, detecting additional radio bursts, exploring possible X-ray counterparts, and updating the FRB detection rate, providing insights into its properties and environment.

Contribution

It reports new radio bursts from FRB 121102, investigates potential X-ray counterparts, and refines the FRB detection rate, advancing understanding of repeating FRBs and their environments.

Findings

Six new radio bursts detected from FRB 121102.

Possible X-ray counterpart identified, but chance superposition remains high.

Updated FRB detection rate in the PALFA survey to approximately 1.1×10^4 sky$^{-1}$ day$^{-1}$.

Abstract

We report on radio and X-ray observations of the only known repeating Fast Radio Burst (FRB) source, FRB 121102. We have detected six additional radio bursts from this source: five with the Green Bank Telescope at 2 GHz, and one at 1.4 GHz at the Arecibo Observatory for a total of 17 bursts from this source. All have dispersion measures consistent with a single value ($\sim559$ pc cm$^{-3}$) that is three times the predicted maximum Galactic value. The 2-GHz bursts have highly variable spectra like those at 1.4 GHz, indicating that the frequency structure seen across the individual 1.4 and 2-GHz bandpasses is part of a wideband process. X-ray observations of the FRB 121102 field with the Swift and Chandra observatories show at least one possible counterpart; however, the probability of chance superposition is high. A radio imaging observation of the field with the Jansky Very Large Array at 1.6 GHz yields a 5$\sigma$ upper limit of 0.3 mJy on any point-source continuum emission. This upper limit, combined with archival WISE 22-$\mu$m and IPHAS H$\alpha$ surveys, rules out the presence of an intervening Galactic HII region. We update our estimate of the FRB detection rate in the PALFA survey to be 1.1$^{+3.7}_{-1.0} \times 10^4$ FRBs sky$^{-1}$ day$^{-1}$ (95% confidence) for peak flux density at 1.4 GHz above 300 mJy. We find that the intrinsic widths of the 12 FRB 121102 bursts from Arecibo are, on average, significantly longer than the intrinsic widths of the 13 single-component FRBs detected with the Parkes telescope.