We report the results of an XMM-Newton and NuSTAR coordinated observation of
the Supergiant Fast X-ray Transient (SFXT) IGRJ11215-5952, performed on
February 14, 2016, during the expected peak of its brief outburst, which
repeats every about 165 days. Timing and spectral analysis were performed
simultaneously in the energy band 0.4-78 keV. A spin period of 187.0 +/- 0.4 s
was measured, consistent with previous observations performed in 2007. The
X-ray intensity shows a large variability (more than one order of magnitude) on
timescales longer than the spin period, with several luminous X-ray flares
which repeat every 2-2.5 ks, some of which simultaneously observed by both
satellites. The broad-band (0.4-78 keV) time-averaged spectrum was well
deconvolved with a double-component model (a blackbody plus a power-law with a
high energy cutoff) together with a weak iron line in emission at 6.4 keV
(equivalent width, EW, of 40+/-10 eV). Alternatively, a partial covering model
also resulted in an adequate description of the data. The source time-averaged
X-ray luminosity was 1E36 erg/s (0.1-100 keV; assuming 7 kpc). We discuss the
results of these observations in the framework of the different models proposed
to explain SFXTs, supporting a quasi-spherical settling accretion regime,
although alternative possibilities (e.g. centrifugal barrier) cannot be ruled
out.Comment: 13 pages, 11 figures, accepted for publication on The Astrophysical
Journa
