INTEGRAL observation of SWIFT J1756.9-2508 in outburst
ATel #11523; S. Mazzola (Univ. Palermo, Italy), E. Bozzo (ISDC, Switzerland), E. Kuulkers (ESA/ESTEC, Netherlands), C. Ferrigno, V. Savchenko (ISDC, Switzerland), L. Ducci (IAAT, Germany; ISDC, Switzerland)
on 10 Apr 2018; 10:25 UT
Credential Certification: E. Bozzo (enrico.bozzo@unige.ch)
Subjects: X-ray, Binary, Neutron Star
Following the discovery of a new outburst from the accreting millisecond X-ray pulsar SWIFT J1756.9-2508 (ATel #11497, #11502, #11505), a dedicated target of opportunity observation with INTEGRAL was carried out from 2018 April 1 at 08:30 to 23:15 (UTC; total exposure time 85 ks).
The source was detected in the 20-40 keV IBIS/ISGRI mosaic at a significance level of 20 sigma. The estimated flux from the 20-40 keV mosaic is 15.3+/-0.8 mCrab (roughly 1.2E-10 erg/cm^2/s). The ISGRI spectrum of the source (effective exposure time 51.6 ks) could be well described by using a power-law with a photon index of 1.8 +/- 0.2. The 20-100 keV flux measured from the fit is 2.8E-10 erg/cm^2/s.
The source was also detected by JEM-X at a significance of about 8 sigma in the 3-20 keV mosaic. From this mosaic, we estimated a 3-20 keV flux of 14+/-2 mCrab (roughly 3E-10 erg/cm^2/s). No evidence of Type-I X-Ray bursts were found in the JEM-X data.
We are grateful to the INTEGRAL planning team for the rapid scheduling of the observation of SWIFT J1756.9-2508.