XMM-Newton observations of the soft gamma ray repeater SGR 1627-41 in a low luminosity state

Abstract

The sky region containing the soft gamma-ray repeater SGR 1627-41 has been observed three times with XMM-Newton in February and September 2004. SGR 1627-41 has been detected with an absorbed flux of ∼9 × 10-14 erg cm-2 s-1 (2-10 keV). For a distance of 11 kpc, this corresponds to a luminosity of ∼3 × 1033 erg s -1, the smallest ever observed for a Soft Gamma Repeater and possibly related to the long period of inactivity of this source. The observed flux is smaller than that seen with Chandra in 2001-2003, suggesting that the source was still fading and had not yet reached a steady quiescent level. The spectrum is equally well fit by a steep power law (photon index ∼3.2) or by a blackbody with temperature kT ∼ 0.8 keV. We also report on the INTEGRAL transient IGR J16358-4726 that lies at ∼10′ from SGR 1627-41. It was detected only in September 2004 with a luminosity of ∼4×1033 erg s -1 (for d = 7 kpc), while in February 2004 it was at least a factor 10 fainter. © ESO 2006.