Single-pulse radio observations of the Galactic Center magnetar PSR J1745-2900

TL;DR

This study presents multi-epoch radio observations of the Galactic Center magnetar PSR J1745-2900, revealing erratic flux variations, narrow bright pulses, and properties akin to normal pulsar emission, using the new Shanghai Tian Ma Radio Telescope.

Contribution

First detailed single-pulse analysis of PSR J1745-2900 at 8.6 GHz across multiple epochs, highlighting its erratic behavior and spiky pulse characteristics.

Findings

Flux density varied significantly across epochs.

Detected 53 bright pulses with peak flux ten times the average.

Bright pulses are narrow and concentrated at pulse peaks.

Abstract

In this paper, we report radio observations of the Galactic Center magnetar PSR J1745-2900 at six epochs between June and October, 2014. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745-2900 show dramatic changes from epoch to epoch showing that the pulsar was in its "erratic" phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was ten times large than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow "spiky" pulses which follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux density is ten times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses was between 0.2 to 0.9 deg, much narrower than that of integrated profile (~12 deg). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of observation, showing the same properties as that detected in MJD 56836. These strong spiky pulses cannot be classified as "giant" pulses but are more closely related to normal pulse emission.