Multifaced Emission Variability of Pulsar J0846–3533: Periodic Amplitude Modulation, Mode Switching, and Pulse Nulling

Abstract We present a comprehensive single-pulse analysis of the isolated rotation-powered pulsar J0846−3533 (B0844−35) using ultrawideband observations from the Parkes 64 m radio telescope across two epochs, totaling 11,103 single pulses. Our study reveals three key emission variability phenomena coexisting in this pulsar: periodic amplitude modulation, mode switching, and intermittent nulling. The nulling fraction is measured to be an upper limit of ∼11%. Mode switching occurs between two distinct states: a normal mode dominated by the trailing component and an abnormal mode with a significantly enhanced central component, transitioning over a few pulse periods. Fluctuation spectral analysis identifies stable periodic amplitude modulation with a periodicity of two rotational periods, which persists across both observational epochs. These findings suggest that mode switching and nulling arise from large-scale magnetospheric current rearrangements, while the periodic amplitude modulation reflects recurrent reconfiguration of particle acceleration and plasma emission efficiency. This multifaceted variability provides critical constraints on unifying models of pulsar magnetospheric dynamics.