NuSTAR pulsar discoveries: SGR J1745-2900 near the Galactic Center and PSR J1640- 4631 associated with HESS J1640-465
Abstract
Two young pulsars have been discovered using the NuSTAR observatory over the last year. SGR J1745-2900: this 3.76 s transient magnetar was detected during a NuSTAR ToO followup of a large flare observed by Swift towards the Galactic center. Its large, erratic spin-down implies a magnetic field B_{s} ∼ 1.6×10^{14} G and characteristic age τ∼ 9 kyr. We followed the magnetar's spectral and timing evolution 4 months post-outburst as its flux and temperature leveled off. In 2013 June, we observed an abrupt tripling of its spin-down rate, likely coincident with a bright Swift burst. We discuss implications of a magnetar near Sgr A*. PSR J1640-4631: This energetic 206 ms pulsar and its surrounding PWN lies within SNR G338.3-0.0 and is likely associated with the extreme gamma-ray sources HESS J1640-465 and 1FHL J1640.5-4634. Its spin-down rate implies a B_{s}=1.4×10^{13} G, τ=3350 yrs, and dot E=4.4×10^{36} erg/s. The origin of the gamma-ray emission is difficult to discern given the complex local environment, both leptonic and hadronic model for the emission mechanism have been proposed. The present work supports an evolutionary PWN model for the spectrum energy distribution, provided that the pulsar's braking index is n≈2, and that its initial spin period was <22 ms. A NuSTAR program to measure its braking index is underway.
- Publication:
-
The X-ray Universe 2014
- Pub Date:
- July 2014
- Bibcode:
- 2014xru..confE..85G