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INTEGRAL detection of SMC X-2 in outburst

ATel #8207; S. Fotopoulou (ISDC, Switzerland), M. J. Coe, A. J. Bird (Southampton Univ., UK), V. McBride (Univ. of Cape Town, South Africa), E. Bozzo (ISDC, Switzerland)
on 22 Oct 2015; 17:57 UT
Credential Certification: E. Bozzo (enrico.bozzo@unige.ch)

Subjects: X-ray, Binary, Transient

The new outburst of the high mass X-ray binary SMC X-2 (Atel #8088, #8091, #8093) was also observed by the instruments on-board INTEGRAL during the observation of the Small Magellanic Cloud performed from 2015 October 20 at 20:27 to October 22 at 04:05 (UTC).

The source was detected by both the IBIS/ISGRI and the JEM-X units. The IBIS/ISGRI detection significance was of 18 sigma in the 20-40 keV energy band, and the corresponding flux was 10.7+/-0.6 mCrab. The source was detected by JEM-X at 12 sigma in the 3-10 keV energy band and 8 sigma in the 10-20 keV energy band. The corresponding fluxes were 6.0+/-0.5 mCrab and 9+/-1 mCrab.

The combined IBIS/ISGRI+JEM-X broad-band spectrum could be well fit (chi^2_red/d.o.f=0.9/9) by using a simple cut-off power-law model. We measured a power-law photon index of 0.5+/-0.4 and a cut-off energy of 11+/-4 keV. The fluxes estimated from the spectral fit were of 3E-10 erg/cm^2/s and 1.9E-10 erg/cm^2/s in the 5-20 keV and 20-100 keV energy band, respectively.

Follow-up ToO observations using XMM and NuSTAR are also taking place at this time.