2025/05/13 by Tian, J., Pastor-Marazuela, I., Rajwade, K. M. +17 · 4 citations
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2505.08372
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 - 1712MHz). We conducted follow-up observations of FRB 20240619D with MeerKAT using the Ultra-High Frequency (UHF; 544 - 1088MHz), L-band and S-band (1968 - 2843MHz) 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 ~1Jy 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 0.76Jy ms and an optical-to-radio fluence ratio limit of 0.034 for a 15s exposure.