A repeating fast radio burst

Abstract

Fast Radio Bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances [1][2][3][4][5][6][7][8] . Previous follow-up observations have failed to find additional bursts at the same dispersion measures (i.e. integrated column density of free electrons between source and telescope) and sky position as the original detections 9 . The apparent non-repeating nature of the fast radio bursts has led several authors to hypothesise that they originate in cataclysmic astrophysical events 10 . Here we report the detection of ten additional bursts from the direction of FRB 121102, using the 305-m Arecibo telescope. These new bursts have dispersion measures and sky positions consistent with the original burst 4 . This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or shorter. While there may be multiple physical origins for the population of fast radio bursts, the repeat bursts with high dispersion measure and variable spectra specifically seen from FRB 121102 support models that propose an origin in a young, highly magnetised, extragalactic neutron star 11,12 .2 FRB 121102 was discovered 4 in the PALFA survey, a deep search of the Galactic plane at 1.4 GHz for radio pulsars and fast radio bursts (FRBs) using the 305-m William E. Gordon Telescope at the Arecibo Observatory and the 7-beam Arecibo L-band Feed Array (ALFA) 13,14 . The observed dispersion measure (DM) of the burst is roughly three times the maximum value expected along this line of sight in the NE2001 model 15 of Galactic electron density, i.e. β DM ≡ DM FRB /DM Gal Max ∼ 3, suggesting an extragalactic origin.Initial Arecibo follow-up observations were limited in both dwell time and sky coverage and resulted in no detection of additional bursts 4 . In 2015 May and June we carried out more extensive follow-up using Arecibo, covering a ∼ 9 radius with a grid of six ALFA pointings around the then-best sky position of FRB 121102 (Figure 1 and Extended Data Table 1 and 2). As described in the Methods, high-time-resolution, total intensity spectra were recorded, and the data were processed using standard radio-frequency interference (RFI) excision, dispersion removal, and single-pulse-search algorithms implemented in the PRESTO software suite and associated data reduction pipelines 14,16,17 .We detected 10 additional bursts from FRB 121102 in these observations. The burst properties, and those of the initial FRB 121102 burst, are listed in Table 1. The burst intensities are shown in Figure 2. No other periodic or single-pulse signals of a plausible astrophysical origin were detected at any other DM. Until the source's physical nature is clear, we continue to refer to it as FRB 121102 and label each burst chronologically starting with the o...

Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes

“…The Parkes and ASKAP radio telescopes searched for FRBs in NGC 4993 after the BNS merger for a total of 5 and 18.7 h, respectively. No FRB was detected: a signal from a source at ∼40 Mpc with similar properties of the repeating FRB 121102 (Spitler et al 2016) would have resulted in a highly significant detection.…”

“…If the neutron star merger produced a massive (>2 M ) neutron star instead of a black hole, it would be expected to possess a spin period close to the break-up velocity of ∼1 ms and potentially a large magnetic field generated during its formation. Such objects (millisecond magnetars) are a potential source of FRBs or possibly even repeating FRBs (Spitler et al 2016;Metzger, Berger, & Margalit 2017). The FRB should be detectable at S/N > 100 with Parkes at the distance of NGC 4993, if appropriately beamed and not hidden by the ejecta from the merger.…”

Fast Radio Bursts as Probes of Magnetic Fields in the Intergalactic Medium

“…Keane et al (2016) have claimed 9 an identification of host elliptical galaxy at z=0.492±0.008 for FRB 150418 with DM=776.2±0.5 pc cm −3 and RM=+36±52 rad m −2 . Spitler et al (2016) and Scholz et al (2016) have presented observations of repeating bursts for FRB 121102, suggesting that the source object could be a young neutron star.…”

“…Dispersion measure (DM), the free electron column density along the LOS, has been suggested as a possible probe of the IGM density (Ioka 2003;Inoue 2004), but can only be measured for the IGM by observation of a bright, brief, radio transient at cosmological distances. Fast radio bursts (FRBs) are a new phenomenon which appear to indeed provide us with these measurements of extragalactic DMs (Lorimer et al 2007(Lorimer et al , 2013; Keane et al 2012Keane et al , 2016Kashiyama et al 2013; Thornton et al 2013;Totani 2013;Zhang 2014;Champion et al 2015;Macquart et al 2015;Masui & Sigurdson 2015;Petroff et al 2015;Spitler et al 2016).…”

Why ultra-powerful radio bursts are the most perplexing mystery in astronomy

“…An important clue arrived earlier this year when Spitler's team reported that at least one FRB source repeats: data from Arecibo revealed a flurry of bursts over two months, some spaced just minutes apart 7 . That behaviour has been confirmed by the Green Bank telescope, which detects signals in a different frequency band 8 .…”