Detection of Fast Radio Bursts

Artist's impression of a fast radio burst. Image credit: CSIRO/Dr. Andrew Howells

Fast Radio Bursts (FRBs) are brief, bright flashes of radio waves that last only a few milliseconds of extragalactic origin. They are one of the most mysterious phenomena in astrophysics, and their progenitor(s) are still unknown. The key characteristic of FRBs is their dispersion measure (DM) i.e. the frequency dependent delay due to electrons in the line of sight, and FRBs have DMs more than the Galactic contribution. DMs allow for study of FRBs’ host galaxies, and combined with their polarization properties measured using rotation measure (RM), magnetars are thought to be the best candidate for FRB progenitors.

The first FRB was discovered while reviewing data in radio pulsar surveys taken using the Parkes Telescope (Lorimer et al., 2007). Since then, hundreds of FRBs have been discovered, especially using instruments with large FOVs such as the Five-hundred-meter Aperture Spherical Telescope (FAST) and the Canadian Hydrogen Intensity Mapping Experiment (CHIME).

Waterfall plot of the first FRB discovered, FRB 010724

Previously, FRB detection are performed using pulsar signal processing programs (e.g. SIGPROC and PRESTO). Currently, there are various FRB detection codes available, mainly optimizing the computationally intensive dedispersion process. One of them is the Burst Emission Automatic Roger (BEAR) program, which is a standalone C++ pipeline for FRB detection developed for various Chinese telescopes (Men et al., 2019). Alternatively, the Python Language Radio Burst Emission Automatic Roger (PoLaR BEAR) program has been developed to provide a more human-readable syntax and easier/direct manipulation of the detection process (Nazri, 2021).

References

A Bright Millisecond Radio Burst of Extragalactic Origin
D. R. Lorimer, M. Bailes, M. A. McLaughlin, D. J. Narkevic, and F. Crawford, ...

Science, 318(5851), Nov 2007

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Piggyback search for fast radio bursts using Nanshan 26 m and Kunming 40 m radio telescopes - I. Observing and data analysis systems, discovery of a mysterious peryton
Y P Men, R Luo, M Z Chen, L F Hao, K J Lee, ...

Monthly Notices of the Royal Astronomical Society, 488(3), Jul 2019

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Fast Radio Bursts: Detection with Python Language Radio Burst Emission Automatic Roger (PoLaR BEAR)
Affan Adly Nazri

Bachelor's thesis, Universiti Malaya, Jun 2021

Abstract Code PDF

Fast radio bursts (FRB) are bright, broadband radio emissions with durations of milliseconds or less. These mysterious astrophysical phenomena are characterized by their frequency-dependent delay in the signal, also known as dispersion measure or DM. Almost all FRBs detected have DMs more than the contribution from the Milky Way, suggesting that they are extragalactic. The exact source of FRBs is uncertain, but most evidence seem to point towards magnetars, which are neutron stars with strong magnetic fields. Finding a larger sample of FRBs would be paramount in confirming and understanding the exact progenitor and burst mechanism for FRBs. Here, a Python program to detect FRBs in radio telescope data is developed based on BEAR. The program performs various functions, most importantly RFI mitigation, dedispersion, and matched filtering based on the likelihood statistic ratio test. The program then outputs FRB candidates which are detected in the data. The program manages to detect all FRBs in the real FRB data and generated FRB data with deviations comparable to BEAR. The program is expected to provide a simpler understanding in the FRB detection methodology.