Suzaku Observation of the New Soft Gamma Repeater SGR 0501+4516 in Outburst
Sakamoto, T.; Tiengo, A.; Hurley, K.; Götz, D.; Mereghetti, S.; Stella, L.; Yamaoka, K.; Rea, N.; Esposito, P.; Yamada, S.; Israel, G. L.; Zane, S.; Turolla, R.; Enoto, T.; Murakami, H.; Makishima, K.; Yoshida, A.; Nakazawa, K.; Nakagawa, Y. E.; Kokubun, M.
Japan, Netherlands, Italy, France, United States, United Kingdom
Abstract
We present the first Suzaku observation of the new Soft Gamma Repeater, SGR 0501+4516, performed on 2008 August 26, four days after the onset of bursting activity of this new member of the magnetar family. The soft X-ray persistent emission was detected with the X-ray Imaging Spectrometer (XIS) at a 0.5-10 keV flux of 3.8 × 10-11 erg s-1cm-2, with a spectrum well fitted by an absorbed blackbody plus power-law model. The source pulsation was confirmed at a period of 5.762072 ± 0.000002 s, and 32 X-ray bursts were detected by the XIS, four of which were also detected at higher energies by the Hard X-ray Detector (HXD). The strongest burst, which occurred at 03:16:16.9 (UTC), was so bright that it caused instrumental saturation, but its precursor phase, lasting for about 200 ms, was detected successfully over the 0.5-200 keV range, with a fluence of ~2.1 × 10-7 erg cm-2 and a peak intensity of about 89 crab. The entire burst fluence is estimated to be ~50 times higher. The precursor spectrum was very hard, and well modeled by a combination of two blackbodies. We discuss the bursting activity and X/γ-ray properties of this newly discovered Soft Gamma Repeater in comparison with other members of the class.