The source undergoing an outburst in NGC 6440 has been recently reported to be likely the neutron star low mass X-ray binary SAX J1748.9-2021 (Atel #10821, #10826, #10827). The source is detected in the IBIS/ISGRI mosaic with a significance of 10 sigma (20-40 keV) and a flux of 30+/-3 mCrab. The IBIS/ISGRI spectrum (effective exposure time 7.7 ks) could be reasonably well fit by using a power-law model with a photon index of 2.2(-0,7,+1.0). The 20-100 keV flux estimated from the spectral fit was 3.7E-10 erg/cm^2/s. The source was outside the JEM-X field of view for the entire observational period.
A new outburst from a source likely located within Terzan 6 was discovered during the same observations in the JEM-X data (and also confirmed by MAXI; see http://maxi.riken.jp/pipermail/x-ray-star/2017-October/002657.html ). Comparing the two independent detections in JEM-X1 and JEM-X2, the best obtained source position is at RA=267.694 and DEC=-31.280, with an associated uncertainty of 1.5 arcmin at 90% c.l. (J2000). This is consistent with the position of Terzan 6, likely indicating that the known neutron-star low-mass X-ray binary GRS 1747-312 is again in outburst. The estimated flux of the source from the two JEM-X mosaics is 22+/-4 mcrab in the 3-10 keV band and 17+/-4 mcrab in 10-25 keV band. No X-ray bursts have been detected in the JEM-X lightcurves. The source was not detected in the IBIS/ISGRI mosaic.
Further INTEGRAL observations of the fields around the two Globular Clusters NGC 6440 and Terzan 6 are already planned in the coming weeks.
|Publication date||9 Oct 2017|
|Publication status||Published - 9 Oct 2017|
|Series||The Astronomer's telegram|
- Neutron Star