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SGR 0501+4516: preliminary results of the first XMM-Newton observation

ATEL # 1688; N. Rea (U. Amsterdam), S. Mereghetti (INAF-IASF, Milan), G.L Israel (INAF-OAR), P. Esposito, A. Tiengo (INAF-IASF, Milan), S. Zane (UCL-MSSL) report on behalf of a larger collaboration
on 2 Sep 2008; 13:58 UT
Password Certification: Nanda Rea (

Subjects: X-ray, Pulsars, Transients
Referred to by ATEL #: 1692

XMM-Newton observed the new Soft Gamma-ray Repeater SGR 0501+4516 (Holland et al., GCN 8112; Barthelmy et al., GCN 8113) for ~49ks on 2008 August 23rd starting at 01:04:00 (UT). Preliminary results show that the source flux is enhanced in the soft X-ray range with respect to the possible quiescent ROSAT counterpart (Kennea et al., Atel 1675).

The source persistent EPIC-PN spectrum is well fitted (in the 1-10keV energy range; reduced chi2 = 1.02) by an absorbed blackbody plus a power-law with Nh = 0.89(2) x 10^22 cm-2, kT = 0.69(5) keV and photon index Gamma= 2.76(6). The absorbed 1-10keV flux is 3.96x10-11 erg/s/cm2.

We measure a spin period of 5.762069(5)s (consistent with the RXTE and Swift-XRT determinations: Gogus et al., Atel 1677; Mangano et al., Atel 1682), with a fundamental component pulsed fraction of 40(1)% (pulsed fraction defined as the background-corrected semi-amplitude of the best fitting sine component, and in the whole EPIC-PN energy band).

Several short X-ray bursts have been detected in this observation, the brightest ones also observed by Swift-BAT (Palmer et al., Atel 1678).

A detailed analysis of this and the subsequent observations of our XMM-Newton monitoring program (Rea et al., GCN 8152) is in progress. Note that we postponed the last observation of our monitoring (September 6th, see GCN 8152), and will promptly diffuse a new date encouraging multiwavelegth follow-ups.

We thank Norbert Schartel and the XMM-Newton team for carrying out this ToO observation.

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R. E. Rutledge , Editor
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