The Lowest-frequency Fast Radio Bursts: Sardinia Radio Telescope Detection of the Periodic FRB 180916 at 328 MHz

Abstract

We report on the lowest-frequency detection to date of three bursts from the fast radio burst FRB 180916.J0158+65, observed at 328 MHz with the Sardinia Radio Telescope (SRT). The SRT observed the periodic repeater FRB 180916.J0158+65 for five days from 2020 February 20 to 24 during a time interval of active radio bursting, and detected the three bursts during the first hour of observations; no more bursts were detected during the remaining ∼30 hr. Simultaneous SRT observations at 1548 MHz did not detect any bursts. Burst fluences are in the range 37 to 13 Jy ms. No relevant scattering is observed for these bursts. We also present the results of the multi-wavelength campaign we performed on FRB 180916.J0158+65, during the five days of the active window. Simultaneously with the SRT observations, others with different time spans were performed with the Northern Cross at 408 MHz, with XMM-Newton, NICER, INTEGRAL, AGILE, and with the TNG and two optical telescopes in Asiago, which are equipped with fast photometers. XMM-Newton obtained data simultaneously with the three bursts detected by the SRT, and determined a luminosity upper limit in the 0.3–10 keV energy range of ∼1045 erg s−1 for the burst emission. AGILE obtained data simultaneously with the first burst and determined a fluence upper limit in the MeV range for millisecond timescales of . Our results show that absorption from the circumburst medium does not significantly affect the emission from FRB 180916.J0158+65, thus limiting the possible presence of a superluminous supernova around the source, and indicate that a cutoff for the bursting mechanism, if present, must be at lower frequencies. Our multi-wavelength campaign sensitively constrains the broadband emission from FRB 180916.J0158+65, and provides the best limits so far for the electromagnetic response to the radio bursting of this remarkable source of fast radio bursts.

Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB ∼ 180916.J0158+65

“…The AGILE limits probe a higher energy range than we considered here with Fermi/GBM. The persistent X-ray emission limits from Swift (Tavani et al 2020b) and XMM-Newton (Pilia et al 2020) are consistent with those we place here.…”

“…Late in the preparation of this work, we became aware of the works of Pilia et al (2020) and Tavani et al (2020b) where limits were placed on the high-energy emission of FRB180916.J0158+65 during its active phases using XMM-Newton, Swift/XRT, and AGILE. The deep XMM-Newton limits placed on the X-ray emission by Pilia et al (2020) at the time of radio bursts using are similar to ours placed here with Chandra. The AGILE limits probe a higher energy range than we considered here with Fermi/GBM.…”

Scintillation Can Explain the Spectral Structure of the Bright Radio Burst from SGR 1935+2154

“…Like the decoherence time, the spatial coherence scale of the scintillation pattern scales as l d ∝ν. While the spatial scale thus decreases at lower frequencies, we would have to observe at frequencies 100 MHz, below the lowest-frequency FRB detections (300 MHz) to date (Chawla et al 2020;Pilia et al 2020), to resolve the spatial scintillation pattern we predict for SGR 1935+2154 using stations across the Earth. At 100 MHz, the scintillation bandwidth is predicted to be ∼24 kHz, requiring observations with fine spectral resolution.…”

The capability of the Australian Square Kilometre Array Pathfinder to detect prompt radio bursts from neutron star mergers

“…Some models (e.g., Pshirkov & Postnov 2010;Hansen & Lyutikov 2001) predict that BNS mergers can produce FRB-like emission at low radio frequencies, 100 MHz, but this is too low for ASKAP, and some of them have a hard cut-off at the high frequency end (e.g., Wang et al 2018). Moreover, no FRBs have been detected at those frequencies (e.g., Rowlinson et al 2016;Chawla et al 2017;Tingay et al 2015;Sokolowski et al 2018, although new detections are coming closer, Pilia et al 2020;Chawla et al 2020), which may influence the BNS/FRB rate comparison (e.g., Callister et al 2016). Wang et al (2016), Ravi & Lasky (2014) and Lyutikov (2013) predict the total power that can be emitted by BNS mergers.…”