Single-Pulse Radio Observations of the Galactic Center Magnetar PSR J1745–2900

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 • , much narrower than that of integrated profile (∼12 • ). 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

TMRT Observations of 26 Pulsars at 8.6 GHz

“…Observations of a sample of 26 pulsars were performed with the TMRT in July 2014, May 2015 and January 2016 at a frequency of 8.6 GHz. The observations were made with incoherent dedispersion and on-line folding by the FPGA-based spectrometer DIBAS (Yan et al 2015). The total recording bandwidth of 800 MHz (8.2−9.0 GHz) was subdivided into 512 frequency channels and each pulsar period was divided into 1024 phase bins.…”

Pulse Morphology of the Galactic Center Magnetar PSR J1745–2900

“…Single pulse radio observations of PSR 1745-2900 have been performed at 8.7 GHz by Lynch et al (2015) with the Green Bank Telescope (GBT) and at 8.6 GHz by Yan et al (2015) using the Shanghai Tian Ma Radio Telescope (TMRT). Lynch et al (2015) showed that the magnetar experienced a transition from a stable state to a more erratic state early in 2014.…”

Observations of Radio Magnetars with the Deep Space Network

“…No correlation has been found between the peak flux density and the number of emission components in the single pulses [18]. In addition, an earlier single pulse analysis by Yan et al [56] at 8.6 GHz revealed no obvious correlation between the width and the peak flux density of the GC magnetar's strongest pulses, and there was no evidence indicating sub-pulse drifting in their observations. Pearlman et al [18] found that the typical intrinsic pulse width of the emission components was ∼1.8 ms, and they reported a prevailing delay time of ∼7.7 ms between successive components.…”

“…In particular, Pearlman et al [18] measured a scaling exponent of Γ = -7 ± 1 from a power-law fit to the distribution of single pulse flux den-sities with peak fluxes greater than 15 times the mean level. The pulse intensity distribution is likely variable in time since a high flux tail has not persistently been observed from the GC magnetar [18,54,56,57]. No correlation has been found between the peak flux density and the number of emission components in the single pulses [18].…”