FRB microstructure revealed by the real-time detection of FRB170827

Abstract

We report a new Fast Radio Burst (FRB) discovered in real-time as part of the UTMOST project at the Molonglo Observatory Synthesis Radio Telescope (MOST). FRB170827 is the first detected with our low-latency (< 24 s), machine-learning-based FRB detection system. The FRB discovery was accompanied by the capture of voltage data at the native time and frequency resolution of the observing system, enabling coherent dedispersion and detailed off-line analysis, which have unveiled fine temporal and frequency structure. The dispersion measure (DM) of 176.80 ± 0.04 pc cm −3 , is the lowest of the FRB population. The Milky Way contribution along the line of sight is ∼ 40 pc cm −3 , leaving an excess DM of ∼ 145 pc cm −3 . The FRB has a fluence > 20 ± 7 Jy ms, and is narrow, with a width of ∼ 400 µs at 10% of its maximum amplitude. However, the burst shows three temporal components, the narrowest of which is ∼ 30 µs, and a scattering timescale of 4.1 ± 2.7 µs. The FRB shows spectral modulations on frequency scales of 1.5 MHz and 0.1 MHz. Both are prominent in the dynamic spectrum, which shows a very bright region of emission between 841 and 843 MHz, and weaker, patchy emission across the entire band. We show the fine spectral structure could arise in the FRB host galaxy, or its immediate vicinity.

The UTMOST pulsar timing programme – II. Timing noise across the pulsar population

“…This programme runs in parallel with searches for undiscovered pulsars and single pulses from rotating radio transients (RRATs), and Fast Radio Bursts (FRBs). These searches have already led to the discovery of thirteen FRBs (Caleb et al 2017;Farah et al 2018Farah et al , 2019Gupta et al 2019a,b,c,d) and the intermittent pulsar candidate PSR J1659−54 (Venkatraman Kr-E-mail: mlower@swin.edu.au 1 Not an acronym. ishnan et al 2020).…”

Magnetars from Neutron Star–White Dwarf Mergers: Application to Fast Radio Bursts

“…Fast radio bursts (FRBs) have remained an extragalactic enigma so far (Katz 2018;Popov et al 2018;Petroff et al 2019;Cordes & Chatterjee 2019) since they were discovered by Lorimer et al (2007), Keane et al (2012), and Thornton et al (2013). They are millisecond-duration coherent radio pulses with average upper limits of the peak luminosity L p ∼ 1 × 10 42 − 8 × 10 44 erg s −1 and energy E ∼ 7 × 10 39 − 2 × 10 42 erg (Zhang 2018), characterized by a single peak mainly or multiple peaks rarely (Champion et al 2016;Farah et al 2018;Prochaska et al 2019), phenomenally divided into repeating bursts (Spitler et al 2016;CHIME/FRB Collaboration et al 2019a,b;Kumar et al 2019;CHIME/FRB Collaboration et al 2020) and non-repeating bursts.…”

FRB coherent emission from decay of Alfvén waves

“…It is firmly established that at least a few milli-second duration, very bright, radio signals that have been detected between about 400 MHz and 7 GHz (known as Fast Radio Bursts or FRBs) are coming from a distance of about a Gpc or more, eg. Lorimer et al 2007; Thornton et al 2013;Spitler et al 2014;Petroff et al 2016;Bannister et al 2017;Law et al 2017;Chatterjee et al 2017;Marcote et al 2017;Tendulkar et al 2017;Gajjar et al 2018;Michilli et al 2018;Farah et al 2018;Shannon et al 2018;Oslowski et al 2019;Kocz et al 2019;Bannister et al 2019;CHIME Collaboration 2019a and2019b;Ravi 2019aRavi , 2019bRavi et al 2019. Many mechanisms have been suggested for the generation of high luminosity coherent radio waves from Fast Radio Bursts (FRBs), eg. Katz (2014Katz ( , 2016, Murase et al (2016;, Kumar et al (2017), Metzger et al (2017), Zhang (2017), Beloborodov (2017), Cordes (2017), Ghisellini & Locatelli (2018), Lu & Kumar (2018), Metzger et al (2019), Thompson (2019), Wang & Lai (2019), ; for a recent review see Katz (2018).…”