Flaring activity and cyclotron line in GX 304-1 observed with INTEGRAL
ATel #3902; D. Klochkov, A. Santangelo, R. Staubert, V. Doroshenko, G. Puehlhofer (IAAT), C. Ferrigno, E. Bozzo, C. Tchernin (ISDC), I. Caballero (CEA Saclay), P. Kretschmar (ESA), I. Kreykenbohm, J. Wilms (Univ. Erlangen-Nuernberg), K. Pottschmidt (CRESST-UMBC/NASA-GSFC), R. E. Rothschild (UCSD), C. A. Wilson-Hodge (NASA-MSFC), V. McBride (SAAO/UCT), G. Schoenherr (AIP)
on 1 Feb 2012; 11:43 UT
Credential Certification: Dmitry Klochkov (klochkov@astro.uni-tuebingen.de)
The INTEGRAL monitoring of the on-going outburst of the transient accreting
pulsar GX 304-1 with a Be optical companion revealed strong flaring
activity with X-ray flux variations by a factor of ~2 on
a time scale of ~1 hour (18-80 keV).
The INTEGRAL observations started around MJD 55943. The maximum flux
level measured by ISGRI so far is 964 +/- 2 mCrab in the 20-40 keV range.
The cyclotron resonance scattering feature is present in the ISGRI
and SPI spectra of the source. In the ISGRI data taken around
MJD ~55944, it can be modeled with a
Gaussian absorption line with a best fit centroid energy of 52.4 +/-1.3 keV and
a width (sigma) of 6+/-1 keV. Due to the possibility that
the observations are affected by solar flares, the actual line
position might be subject to systematic uncertainties at the level
of a few keV. The detailed spectral study is ongoing.
We thank the INTEGRAL team for the effective communication and prompt
scheduling of the TOO observations.
