An Extreme Radio Fluctuation of Pulsar B1929$+$10

TL;DR

This study reports an extreme, rapid flux decrease in pulsar B1929+10 accompanied by DM and RM variations, likely caused by a dense outflow or plasma lens, affecting both emission and timing.

Contribution

First detection of an extreme flux fluctuation with associated DM and RM changes in pulsar B1929+10 using FAST, suggesting new insights into pulsar environment interactions.

Findings

Flux decreased by 2-3 orders of magnitude within 20 minutes.

DM and RM variations of 0.05 pc cm$^{-3}$ and 0.7 rad m$^{-2}$ observed.

Event possibly caused by dense outflow or plasma lens effect.

Abstract

We report the detection of an extreme flux decrease accompanied by clear dispersion measure (DM) and rotation measure (RM) variations for pulsar B1929+10 during the 110-minute radio observation with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The radio flux decreases by 2 to 3 orders of magnitude within a rapid time scale of about 20 minutes. Meanwhile, the variations of DM and RM are approximately 0.05 pc cm$^{-3}$ and 0.7 rad m$^{-2}$, respectively. Frequency-dependent analysis of DM indicates an extremely weak chromatic DM feature, which does not notably affect the radiative behavior detected. Moreover, the pulsar timing analysis shows an additional time delay from 100 $\mu$s to 400 $\mu$s in the event. These results are speculated to be due to the eclipse and bend for the radio emission of pulsar B1929+10 by a highly dense outflow from the pulsar. This not only impacts the intrinsic radio emission feature but also affects the pulsar timing behavior. Nevertheless, a plasma lens effect lasting around 20 minutes could also be responsible for the event.