Periodic and Phase-locked Modulation in PSR B1929+10 Observed with FAST

TL;DR

This study uses FAST telescope data to analyze PSR B1929+10, revealing phase-locked periodic amplitude modulation in its pulses, with implications for understanding pulsar emission mechanisms and magnetospheric structure.

Contribution

First detailed single-pulse analysis of PSR B1929+10 with FAST, uncovering phase-locked periodic modulation and weak emissions, challenging existing pulsar models.

Findings

Periodic modulation with ~12P in main and interpulse

Modulation is amplitude-based, not drifting

Modulation in MP_II delayed by about 1P from IP

Abstract

We present a detailed single-pulse analysis for PSR B1929+10 based on observations with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The main pulse and interpulse are found to be modulated with a periodicity of $\sim12$ times the pulsar's rotational period ($P$). The $\sim12P$ modulation is confirmed as a periodic amplitude modulation instead of systematic drifting. The periodic amplitude modulation in the IP is found to be anti-correlated with that in the weak preceding component of the MP (MP_I), but correlated with that in the first two components of the MP (MP_II), which implies that the modulation patterns in the IP and the MP are phase-locked. What is more interesting is that the modulation in MP_II is delayed that in the IP by about 1P. Furthermore, high sensitivity observations by FAST reveal that weak emission exists between the MP and the IP. In addition, we confirm that the separation between the IP and the MP is independent of radio frequency. The above results are a conundrum for pulsar theories and cannot be satisfactorily explained by the current pulsar models. Therefore, our results observed with FAST provide an opportunity to probe the structure of pulsar emission and the neutron star's magnetosphere.