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arXiv · 1010.2781

A low-magnetic-field Soft Gamma Repeater

N. Rea·P. Esposito·R. Turolla·G. L. Israel·S. Zane·L. Stella·S. Mereghetti·A. Tiengo·D. Gotz·E. Gogus·C. Kouveliotou
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Abstract

Soft gamma repeaters and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, i.e. neutron stars powered by extreme magnetic fields, B~10^{14}-10^{15} Gauss. We report on a soft gamma repeater with low magnetic field, SGR 0418+5729, recently detected after it emitted bursts similar to those of magnetars. X-ray observations show that its dipolar magnetic field cannot be greater than 7.5x10^{12} Gauss, well in the range of ordinary radio pulsars, implying that a high surface dipolar magnetic field is not necessarily required for magnetar-like activity. The magnetar population may thus include objects with a wider range of B-field strengths, ages and evolutionary stages than observed so far.

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N. Rea, P. Esposito, R. Turolla, G. L. Israel, S. Zane, L. Stella, S. Mereghetti, A. Tiengo, D. Gotz, E. Gogus, C. Kouveliotou. 2010-10-13. A low-magnetic-field Soft Gamma Repeater. https://doi.org/10.1126/science.1196088

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