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1. A search for fast-radio-burst-like emission from Fermi gamma-ray bursts

   https://doi.org/10.1093/mnras/staa1889  

   Bouwhuis, Mieke ; Bannister, Keith W ; Macquart, Jean-Pierre ; Shannon, R M ; Kaplan, David L ; Bunton, John D ; Koribalski, Bärbel S ; Whiting, M T ( September 2020 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We report the results of the rapid follow-up observations of gamma-ray bursts (GRBs) detected by the Fermi satellite to search for associated fast radio bursts. The observations were conducted with the Australian Square Kilometre Array Pathfinder at frequencies from 1.2 to 1.4 GHz. A set of 20 bursts, of which four were short GRBs, were followed up with a typical latency of about 1 min, for a duration of up to 11 h after the burst. The data were searched using 4096 dispersion measure trials up to a maximum dispersion measure of 3763 pc cm−3, and for pulse widths w over a range of duration from 1.256 to 40.48 ms. No associated pulsed radio emission was observed above $26 \, {\rm Jy\, ms}\, (w/1\, {\rm ms})^{-1/2}$ for any of the 20 GRBs.
2. The First CHIME/FRB Fast Radio Burst Catalog

   https://doi.org/10.3847/1538-4365/ac33ab  

   Amiri, Mandana ; Andersen, Bridget C. ; Bandura, Kevin ; Berger, Sabrina ; Bhardwaj, Mohit ; Boyce, Michelle M. ; Boyle, P. J. ; Brar, Charanjot ; Breitman, Daniela ; Cassanelli, Tomas ; et al ( December 2021 , The Astrophysical Journal Supplement Series)

   We present a catalog of 536 fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project between 400 and 800 MHz from 2018 July 25 to 2019 July 1, including 62 bursts from 18 previously reported repeating sources. The catalog represents the first large sample, including bursts from repeaters and nonrepeaters, observed in a single survey with uniform selection effects. This facilitates comparative and absolute studies of the FRB population. We show that repeaters and apparent nonrepeaters have sky locations and dispersion measures (DMs) that are consistent with being drawn from the same distribution. However, bursts from repeating sources differ from apparent nonrepeaters in intrinsic temporal width and spectral bandwidth. Through injection of simulated events into our detection pipeline, we perform an absolute calibration of selection effects to account for systematic biases. We find evidence for a population of FRBs—composing a large fraction of the overall population—with a scattering time at 600 MHz in excess of 10 ms, of which only a small fraction are observed by CHIME/FRB. We infer a power-law index for the cumulative fluence distribution of$\alpha =-1.40\pm 0.11(\mathrm{stat.}{)}_{-0.09}^{+0.06}(\mathrm{sys.})$, consistent with the −3/2more »expectation for a nonevolving population in Euclidean space. We find thatαis steeper for high-DM events and shallower for low-DM events, which is what would be expected when DM is correlated with distance. We infer a sky rate of$[820\pm 60(\mathrm{stat.}{)}_{-200}^{+220}(\mathrm{sys.})]/\mathrm{sky}/\mathrm{day}$above a fluence of 5 Jy ms at 600 MHz, with a scattering time at 600 MHz under 10 ms and DM above 100 pc cm⁻³.

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3. Search for fast radio transients using Arecibo drift-scan observations at 1.4 GHz

   https://doi.org/10.1093/mnras/stab3153  

   Perera, B B ; Smith, A J ; Vaddi, S ; Carballo-Rubio, R ; McGilvray, A ; Venkataraman, A ; Roshi, D Anish ; Manoharan, P K ; Perillat, P ; Lieb, E ; et al ( November 2021 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We conducted a drift-scan observation campaign using the 305-m Arecibo telescope in 2020 January and March when the observatory was temporarily closed during the intense earthquakes and the initial outbreak of the COVID-19 pandemic, respectively. The primary objective of the survey was to search for fast radio transients, including fast radio bursts (FRBs) and rotating radio transients (RRATs). We used the seven-beam ALFA receiver to observe different sections of the sky within the declination region ∼(10°–20°) on 23 nights and collected 160 h of data in total. We searched our data for single-pulse transients, of covering up to a maximum dispersion measure of 11 000 pc cm−3 at which the dispersion delay across the entire bandwidth is equal to the 13-s transit length of our observations. The analysis produced more than 18 million candidates. Machine learning techniques sorted the radio frequency interference and possibly astrophysical candidates, allowing us to visually inspect and confirm the candidate transients. We found no evidence for new astrophysical transients in our data. We also searched for emission from repeated transient signals, but found no evidence for such sources. We detected single pulses from two known pulsars in our observations and their measured flux densities are consistent with themore »expected values. Based on our observations and sensitivity, we estimated the upper limit for the FRB rate to be <2.8 × 105 sky−1 d−1 above a fluence of 0.16 Jy ms at 1.4 GHz, which is consistent with the rates from other telescopes and surveys.« less
4. First discoveries and localizations of Fast Radio Bursts with MeerTRAP: real-time, commensal MeerKAT survey

   https://doi.org/10.1093/mnras/stac1450  

   Rajwade, K. M. ; Bezuidenhout, M. C. ; Caleb, M. ; Driessen, L. N. ; Jankowski, F. ; Malenta, M. ; Morello, V. ; Sanidas, S. ; Stappers, B. W. ; Surnis, M. P. ; et al ( May 2022 , Monthly Notices of the Royal Astronomical Society)

   We report on the discovery and localization of fast radio bursts (FRBs) from the MeerTRAP project, a commensal fast radio transient-detection programme at MeerKAT in South Africa. Our hybrid approach combines a coherent search with an average field-of-view (FoV) of 0.4 $\rm deg^{2}$ with an incoherent search utilizing a FoV of ∼1.27 $\rm deg^{2}$ (both at 1284 MHz). Here, we present results on the first three FRBs: FRB 20200413A (DM = 1990.05 pc cm−3), FRB 20200915A (DM = 740.65 pc cm−3), and FRB 20201123A (DM = 433.55 pc cm−3). FRB 20200413A was discovered only in the incoherent beam. FRB 20200915A (also discovered only in the incoherent beam) shows speckled emission in the dynamic spectrum, which cannot be explained by interstellar scintillation in our Galaxy or plasma lensing, and might be intrinsic to the source. FRB 20201123A shows a faint post-cursor burst of about 200 ms after the main burst and warrants further follow-up to confirm whether it is a repeating FRB. FRB 20201123A also exhibits significant temporal broadening, consistent with scattering, by a turbulent medium. The broadening exceeds from what is predicted for the medium along the sightline through our Galaxy. We associate this scattering with the turbulent medium in the environment of the FRB in the host galaxy. Within the approximately 1 arcmin localization region ofmore »FRB 20201123A, we identify one luminous galaxy (r ≈ 15.67; J173438.35-504550.4) that dominates the posterior probability for a host association. The galaxy’s measured properties are consistent with other FRB hosts with secure associations.

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5. Inferring the Energy and Distance Distributions of Fast Radio Bursts Using the First CHIME/FRB Catalog

   https://doi.org/10.3847/1538-4357/acaf06  

   Shin, Kaitlyn ; Masui, Kiyoshi W. ; Bhardwaj, Mohit ; Cassanelli, Tomas ; Chawla, Pragya ; Dobbs, Matt ; Dong, Fengqiu Adam ; Fonseca, Emmanuel ; Gaensler, B. M. ; Herrera-Martín, Antonio ; et al ( February 2023 , The Astrophysical Journal)

   Fast radio bursts (FRBs) are brief, energetic, typically extragalactic flashes of radio emission whose progenitors are largely unknown. Although studying the FRB population is essential for understanding how these astrophysical phenomena occur, such studies have been difficult to conduct without large numbers of FRBs and characterizable observational biases. Using the recently released catalog of 536 FRBs published by the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) collaboration, we present a study of the FRB population that also calibrates for selection effects. Assuming a Schechter function, we infer a characteristic energy cut-off of$E_{\mathrm{char}}={2.38}_{-1.64}^{+5.35}\times {10}^{41}$erg and a differential power-law index ofγ=$-{1.3}_{-0.4}^{+0.7}$. Simultaneously, we infer a volumetric rate of [${7.3}_{-3.8}^{+8.8}$(stat.)${}_{-1.8}^{+2.0}(\mathrm{sys}.)]\times {10}^4$Gpc⁻³yr⁻¹above a pivot energy of 10³⁹erg and below a scattering timescale of 10 ms at 600 MHz, and find we cannot significantly constrain the cosmic evolution of the FRB population with star-formation rate. Modeling the host’s dispersion measure (DM) contribution as a log-normal distribution and assuming a total Galactic contribution of 80 pc cm⁻³, we find a median value of${\mathrm{DM}}_{\mathrm{host}}={84}_{-49}^{+69}$pc cm⁻³, comparable with values typically used in the literature. Proposed models for FRB progenitors shouldmore »be consistent with the energetics and abundances of the full FRB population predicted by our results. Finally, we infer the redshift distribution of FRBs detected with CHIME, which will be tested with the localizations and redshifts enabled by the upcoming CHIME/FRB Outriggers project.

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