MeerKAT discovery of a hyperactive repeating fast radio burst source

Journal article

We present the discovery and localization of a repeating fast radio burst (FRB) source from the MeerTRAP project, a commensal fast radio transient search programme using the MeerKAT telescope. FRB 20240619D was first discovered on 2024 June 19 with three bursts being detected within 2 min in the MeerKAT L band (856–1712 MHz). We conducted follow-up observations of FRB 20240619D with MeerKAT using the Ultra-High Frequency (UHF; MHz), L-band and S-band (1968–2843 MHz) receivers one week after its discovery, and recorded a total of 249 bursts. The MeerKAT-detected bursts exhibit band-limited emission with an average fractional bandwidth of 0.31, 0.34, and 0.48 in the UHF, L-band, and S-band, respectively. We find our observations are complete down to a fluence limit of Jy ms, above which the cumulative burst rate follows a power law with and in the UHF and L band, respectively. The near-simultaneous L-band, UHF, and S-band observations reveal a frequency dependent burst rate with more bursts being detected in the L band than in the UHF and S band, suggesting a spectral turnover in the burst energy distribution of FRB 20240619D. Our polarimetric analysis demonstrates that most of the bursts have linear polarization fractions and circular polarization fractions. We find no optical counterpart of FRB 20240619D in the MeerLICHT optical observations simultaneous to the radio observations and set a fluence upper limit in MeerLICHT’s q band of 0.76 Jy ms and an optical-to-radio fluence ratio limit of 0.034 for a 15 s exposure.

Authors: Tian, J; Pastor-Marazuela, I; Rajwade, KM; Stappers, BW; Shaji, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 540
• Issue: 2
• Pages: 1685-1700
• Publication date: 2025-05-14
• Acceptance date: 2025-05-12
• DOI: 10.1093/mnras/staf793
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: methods: observational; fast radio bursts; methods: data analysis; techniques: interferometric