Xiaoxi Song | Searcharxiv

arXiv2026

The Thousand-Pulsar-Array programme on MeerKAT XIX: Single-pulse data analysis, nulling and pulse energy distributions

We present the Thousand Pulsar Array (TPA) single-pulse data set, obtained with the MeerKAT radio telescope and comprising time-series observations of 1192 pulsars, typically containing ~1000 consecutive pulses per source. We describe the MeerTime Single Pulse software pipeline which calibrates the data and automatically excises interference signals to produce data products suitable for typical single-pulse studies. To demonstrate the capabilities of the dataset, we carry out a population-level study of phase-averaged single-pulse energy distributions and nulling behaviour. Pulse energy distributions are modelled within a Bayesian framework choosing from a range of intrinsic energy distributions, and including an explicit nulling fraction. We find that approximately half of the pulsars require multi-component intrinsic energy distributions, while the remainder are consistent with single-component models. Nulling is detected or constrained for most pulsars in the sample, and both the occurrence and inferred nulling fraction show systematic variation across the P-$\dot{P}$ diagram. In particular, nulling fractions increase with spin period and exhibit only a weak dependence on period derivative. We also examine trends in the preferred forms of pulse energy distributions as a function of spin-down luminosity, finding modest evidence for population-level evolution. Estimates of single-pulse luminosities indicate that individual pulses can exceed the long-term average luminosity by large factors, particularly for low-$\dot{E}$ pulsars. These results characterise the statistical properties of single-pulse emission across a large pulsar sample and highlight the limitations of phase-averaged energy distributions for capturing the full complexity of pulsar emission variability.

astro-ph.HE↗

arXiv2025

The Thousand-Pulsar-Array programme on MeerKAT -- XVIII. Complex sub-pulse modulation patterns, bi-drifting and mode changing of nine radio pulsars

We present a detailed analysis of sub-pulse modulations in nine pulsars which show evidence of changes in sub-pulse drift direction as a function of pulse longitude in the Thousand Pulsar Array single pulse survey with MeerKAT. We confirm that all of these are consistent with persistent drift direction changes. These 'bi-drifting' pulsars present a challenge to the classical carousel model for sub-pulse drifting. In general, bi-drifting in this expanded sample is less clear than some of the previously published cases, which we attribute to narrower profile widths ($<20$ degrees) or smaller $P_3$ values (close to 2$P$). However, given the broad variety of pulse shapes and drift behaviours across the pulsar population, it is unsurprising that the phenomenon is not limited to only those where it can most easily be detected. Four of our samples show at least two emission modes with different profile shapes and drift properties, which seems to be a relatively common feature of bi-drifting pulsars. We also find jumps in sub-pulse phase between adjacent components in two pulsars. In addition to our MeerKAT L-band data, we used GMRT observations for four, and MeerKAT UHF observations for two of these pulsars to investigate the frequency dependence of sub-pulse drift. We find subtle changes in the drift as a function of frequency, but no clear overall pattern. Looking at the distribution of bi-drifting pulsars over $P$, $\dot{P}$ and $P_3$ suggests they are consistent with the underlying population of all drifting pulsars.

astro-ph.HE↗