MeerKAT discovery of a hyperactive repeating fast radio burst source
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2025)
Authors:
J Tian, I Pastor-Marazuela, KM Rajwade, BW Stappers, K Shaji, KY Hanmer, M Caleb, MC Bezuidenhout, F Jankowski, R Breton, ED Barr, M Kramer, PJ Groot, S Bloemen, P Vreeswijk, D Pieterse, PA Woudt, RP Fender, RAD Wijnands, DAH Buckley
Abstract:
Abstract
We present the discovery and localisation 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 two minutes in the MeerKAT L-band (856–1712 MHz). We conducted follow-up observations of FRB 20240619D with MeerKAT using the Ultra-High Frequency (UHF; 544–1088 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 ∼1 Jy ms, above which the cumulative burst rate follows a power law R( > F)∝(F/1 Jy ms)γ with γ = −1.6 ± 0.1 and −1.7 ± 0.1 in the UHF and L-band, respectively. The near-simultaneous L-band, UHF and S-band observations reveal a frequency dependent burst rate with 3 × 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 ∼100% linear polarisation fractions and ∼10%–20% circular polarisation 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.
