RRAT-like behaviour of PSR B0656+14 observed with I-LOFAR

TL;DR

This study investigates the low-frequency single pulse behaviour of PSR B0656+14, revealing RRAT-like sporadic emission, variable spectral indices, and a hybrid energy distribution, which impacts pulsar population models.

Contribution

It provides the first detailed low-frequency analysis of PSR B0656+14's single pulses, highlighting RRAT-like behaviour and variability not previously characterized.

Findings

41 pulses detected over 5 hours

Pulse occurrence follows a Poisson process

Significant pulse-to-pulse spectral index variation

Abstract

Single pulse studies offer vital insights into the emission physics of pulsars, particularly in the case of young, nearby sources where intrinsic variability is often pronounced. PSR~B0656+14, known for its sporadic and sometimes intense pulses, provides an excellent opportunity to investigate such behaviour at low radio frequencies. This study aims to characterize the single pulse behaviour of PSR~B0656+14 using low-frequency observations at 110-190 MHz from the Irish LOFAR station. Single-pulse extraction is performed, and individual pulse DMs are estimated to probe pulse-to-pulse dispersion variability. We also perform a wait-time analysis to understand the statistical nature of pulse occurrence, and estimate the spectral index from frequency-resolved flux density measurements. The pulse energy distribution is modelled using a combination of log-normal and power-law components. A total of 41 pulses were detected in a 5-hour observation, allowing a wait-time distribution analysis which is well-modelled by an exponential function, indicative of a Poisson process. Profile stability analysis indicates that a significant number of pulses are required to reach a stable average profile, unusual compared to many other pulsars. The single-pulse spectral index varies significantly from pulse to pulse, with a mean value of $\alpha = -0.5$ and a standard deviation of $\Delta\alpha=1.3$. The pulse energy distribution shows a hybrid behaviour, consistent of a log-normal distribution and a power-law tail. Our results confirm that PSR~B0656+14 exhibits highly variable, memory-less emission at low frequencies, with characteristics that resemble those seen in some rotating radio transients (RRATs). If such variability proves to be widespread among pulsars, population synthesis models and survey yield predictions would need to incorporate this currently overlooked feature to ensure accuracy.