First broad band study of the mysterious source 1E 1743.1–2843

¹ Istituto di Astrofisica Spaziale e Fisica Cosmica di Roma – INAF, via del Fosso del Cavaliere 100, 40133 Roma, Italy e-mail: melania.delsanto@iasf-roma.inaf.it
² Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano – INAF, via E. Bassini 15, 20133 Milano, Italy
³ Dipartimento di Astronomia, Universitá degli Studi di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁴ Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, BP 4346, 31028 Toulouse Cedex 4, France

Received: 15 February 2006
Accepted: 4 July 2006

Abstract

Context.In the last years, the persistent source 1E 1743.1–2843 has been observed in the X-rays, but never above 20 keV. In previous works, it was stressed that a possible high energy emission could give further indications on the accreting object nature which remains still unknown.

Aims.We present here more than two years of 1E 1743.1–2843 monitoring with INTEGRAL/IBIS as well as public XMM-Newton  and Chandra  X-ray observations.

Methods.The temporal study in the 20–40 keV band shows a rather constant flux on few months time scale. Based on this result we have performed the broad-band spectral analysis using EPIC/IBIS non simultaneous data and ACIS-I/IBIS data collected during 2004.

Results.In ~2 Ms, we report a detection of 6σ in the energy range 35–70 keV. The first broad-band study (2–70 keV) shows a steep slope (~3) and a black body temperature of 1.7 keV.

Conclusions.Combining spectral parameters and discussion about the luminosity evaluations for different possible distances, our conclusions are in favour of a LMXB system with a neutron star at distance higher than the Galactic Centre, even though a firm conclusion can not be stated.