Detection of over 37,000 giant pulses per hour from PSR J1823$-$3021A with UHF baseband observations from MeerKAT

TL;DR

This study reports the detection of over 37,000 giant pulses per hour from PSR J1823$-$3021A using MeerKAT UHF observations, revealing detailed properties and potential links to fast radio bursts.

Contribution

First detailed UHF band analysis of PSR J1823$-$3021A showing extremely high GP rate and polarization characteristics, with insights into pulse morphology and scattering.

Findings

GP rate exceeds 37,000 per hour at UHF frequencies

Giant pulses are broadband with steep spectral indices around -3

Detected a mean scattering time of 5.5 microseconds at 1 GHz

Abstract

Giant pulses (GPs) occur in high magnetic-field millisecond pulsars (MSPs) and young Crab-like pulsars. Motivated by the fast radio bursts (FRBs) discovered in a globular cluster (GC) in the M81, we undertook baseband observations of PSR J1823$-$3021A, the most active GP emitter in a GC with the MeerKAT UHF band receiver (544-1088 MHz). The steep spectral index of the pulsar yields a GP rate of over 37,000 GPs/hr with $S/N>7$, significantly higher than the 3000 GPs/hr rate detected by Abbate et al. 2020 with the L-band (856-1712 MHz) receiver. Similarly to Abbate et al 2020, we find that the GPs are (1) strongly clustered in 2 particular phases of its rotation, (2) well described by a power-law in terms of energies, (3) typically broadband, and have steep spectral indices of $\approx-3$. Although the integrated pulse profile is not significantly polarised ($<1\%$ linear and $<3\%$ circular), one of the brightest GPs displays notable polarisation of $7\%$ (linear) and $8\%$ (circular). The high-time resolution data reveals the GPs have a range of single-peak and multi-peak morphologies, including GPs with three distinct peaks. For the first time, we measured the temporal scattering of the pulsar using 49 bright, narrow, single-pulse GPs, obtaining a mean value of $5.5\pm0.6$ $\mu$s at 1 GHz. The distinct periodicity and low polarisation of GPs differentiate them from typical FRBs, although potential quasi-periodicity substructures in some GPs may suggest a connection to magnetars/FRBs.