Discovery of a new Soft Gamma Repeater, SGR J1833-0832

TL;DR

A new magnetar, SGR J1833-0832, was discovered through its burst and confirmed by its X-ray pulsations, rapid spin-down, and magnetic field, with detailed analyses of its temporal and spectral properties.

Contribution

This paper reports the discovery and detailed characterization of a new Soft Gamma Repeater, including its timing, spectral properties, and magnetic field, expanding the known population of magnetars.

Findings

Discovered a new SGR with a 7.56 s spin period.

Measured a rapid spin-down rate of 4 x 10^{-12} s/s.

Inferred a magnetic field of 1.8 x 10^{14} G.

Abstract

On 2010 March 19, the Swift/Burst Alert Telescope triggered on a short burst with temporal and spectral characteristics similar to those of Soft Gamma Repeater (SGR) bursts. The source location, however, did not coincide with any known SGR. Subsequent observations of the source error box with the Swift/X-ray Telescope and the Rossi X-ray Timing Explorer (RXTE) led to the discovery of a new X-ray source, with a spin period of 7.56 s, confirming SGR J1833-0832 as a new magnetar. Based on our detailed temporal and spectral analyses, we show that the new SGR is rapidly spinning down (4 x 10^{-12} s/s) and find an inferred dipole magnetic field of 1.8 x 10^{14} G. We also show that the X-ray flux of SGR J1833-0832 remained constant for approximately 20 days following the burst and then started to decline. We derived an accurate location of the source with the Chandra X-ray Observatory and we searched for a counterpart in deep optical and infrared observations of SGR J1833-0832, and for radio pulsed emission with the Westerbork Radio Synthesis Telescope. Finally, we compare the spectral and temporal properties of the source to the other magnetar candidates.