The Repeating Fast Radio Burst FRB 121102 as Seen on Milliarcsecond Angular Scales

B Marcote ,Casey J Law ,Shriharsh P Tendulkar ,M A Garrett ,R M Campbell ,Geoffrey C Bower ,Andrew Siemion ,J W T Hessels ,S Burke-Spolaor ,Z Paragi ,Laura Spitler ,Cees Bassa ,Slavko Bogdanov ,T Joseph W Lazio ,Yuping Huang ,C J Salter ,V M Kaspi ,J M Cordes ,B J Butler ,T Ghosh ,S M Ransom ,Andrew Seymour ,A Keimpema ,Paul Scholz ,H J Van Langevelde ,Paul Demorest ,M A Mclaughlin ,Shami Chatterjee ,Robert Wharton

doi:10.3847/2041-8213/834/2/l8

Abstract

Abstract The millisecond-duration radio flashes known as fast radio bursts (FRBs) represent an enigmatic astrophysical phenomenon. Recently, the sub-arcsecond localization (∼100 mas precision) of FRB 121102 using the Very Large Array has led to its unambiguous association with persistent radio and optical counterparts, and to the identification of its host galaxy. However, an even more precise localization is needed in order to probe the direct physical relationship between the millisecond bursts themselves and the associated persistent emission. Here, we report very-long-baseline radio interferometric observations using the European VLBI Network and the 305 m Arecibo telescope, which simultaneously detect both the bursts and the persistent radio emission at milliarcsecond angular scales and show that they are co-located to within a projected linear separation of ≲40 pc (≲12 mas angular separation, at 95% confidence). We detect consistent angular broadening of the bursts and persistent radio source (∼2–4 mas at 1.7 GHz), which are both similar to the expected Milky Way scattering contribution. The persistent radio source has a projected size constrained to be ≲ 0.7 pc (≲0.2 mas angular extent at 5.0 GHz) and a lower limit for the brightness temperature of T b ≳ 5 × 10 7 K . Together, these observations provide strong evidence for a direct physical link between FRB 121102 and the compact persistent radio source. We argue that a burst source associated with a low-luminosity active galactic nucleus or a young neutron star energizing a supernova remnant are the two scenarios for FRB 121102 that best match the observed data.

Highlights

Fast radio bursts (FRBs) are transient sources of unknown physical origin, which are characterized by their short (∼ms), highly dispersed, and bright (Speak ~ 0.1–10 Jy) pulses
Further studies have shown that the transient source continues to vary in brightness well after the initial FRB 150418 burst detection, and can be explained by a scintillating, low-luminosity active galactic nucleus (AGN; e.g., Bassa et al 2016; Giroletti et al 2016; Johnston et al 2017; Williams & Berger 2016), which leaves limited grounds to claim an unambiguous association with FRB 150418
On 2016 September 20, we detected four individual bursts in the Arecibo single-dish Puerto-Rican Ultimate Pulsar Processing Instrument (PUPPI) data that overlap with European VLBI Network (EVN) data acquisition (Table 1)

Summary

Introduction

Fast radio bursts (FRBs) are transient sources of unknown physical origin, which are characterized by their short (∼ms), highly dispersed, and bright (Speak ~ 0.1–10 Jy) pulses. Reported the first apparent localization of an FRB by associating FRB 150418 with a pseudo-contemporaneous transient radio source in a galaxy at z ~ 0.5. Further studies have shown that the transient source continues to vary in brightness well after the initial FRB 150418 burst detection, and can be explained by a scintillating, low-luminosity active galactic nucleus (AGN; e.g., Bassa et al 2016; Giroletti et al 2016; Johnston et al 2017; Williams & Berger 2016), which leaves limited grounds to claim an unambiguous association with FRB 150418

Results

Discussion

Conclusion