INTEGRAL's detection of evolution in MAXI J1348-630

INTEGRAL has recently performed public observations of the Musca and Norma regions during Galactic Plane Scanning program (PI: A. Bazzano). During revolution 2049 (starting from 24 Jan 02.48 UTC) and 2050 (starting from 26 Jan 19:13 UTC) the newly discovered X-ray transient MAXI J1348-630 (ATel #12425, #12430, #12434 and #12439) was detected with IBIS/ISGRI and seen to be evolving.

MAXI J1348-630 returned to the IBIS/ISGRI FOV in ScW 26 of revolution 2050 (ScW starting from 27 Jan 08:15 UTC) and has been monitored since then. In ScW 26, it was detected in the 22-60 keV band with a significance of 185.3 sigma, and the flux was measured in the 22-60 keV band as 1.86 ± 0.01-8 erg cm-2 s-1(1.7 ± 0.01 Crab).

The flux showed a fairly constant rise through the revolution and in ScW 62 (starting from 28 Jan 05:25 UTC), the latest one analysed, MAXI J1348-630 was detected in the 22-60 keV band with a significance of 222.0 sigma. The flux was measured in the 22-60 keV band as 3.25 ± 0.01-8 erg cm-2 s-1 (3.0 ± 0.01 Crab).

An average spectrum for the revolution was obtained in the 30-300 keV range that is well modelled by a cut-off power-law model (with a reduced chi2 of 1.07 for 40 degrees of freedom) with a photon index of 1.18 ± 0.03 and an exponential cutoff at 77.3 keV ± 2.2 keV. Unfortunately data from the JEM-X instrument are not yet available.

All the data have been analysed using the Offline Software Analysis version 11.0 (OSA11). An INTEGRAL ToO will be observing this source starting from January 29th. Results from the Galactic Plane Scanning are made publicly available at: http://gps.iaps.inaf.it