The First XMM-Newton Observations of the Soft Gamma-Ray Repeater SGR 1900+14

A ~50 ks XMM-Newton observation of SGR 1900+14 has been carried out in 2005 September, after almost 3 yr during which no bursts were detected from this soft gamma-ray repeater. The 0.8-10 keV spectrum was well fit by a power law plus blackbody model with photon index \u393=1.9+/-0.1, temperature kT=0.47+/-0.02 keV, and NH=(2.12+/-0.08) 71022 cm-2, similar to previous observations of this source. The flux was ~5 710-12 ergs cm-2 s-1, a factor 2 dimmer than the typical value and the smallest ever seen from SGR 1900+14. The long-term fading of the persistent emission has been interrupted by the recent burst reactivation of the source. A Target of Opportunity XMM-Newton observation performed in 2006 April showed a flux ~15% higher. This variation was not accompanied by significant changes in the spectrum, pulsed fraction, and light-curve profile. We searched for emission and absorption lines in the spectra of the two observations, with negative results and setting tight upper limits of 50-200 eV (3 \u3c3), depending on the assumed line energy and width, on the equivalent width of lines in the 1-9 keV range