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INTEGRAL detection of the multi-peaked emission from the Be/X-ray binary pulsar GRO J1008-57

ATel #6823; M. Fiocchi (INAF-IAPS Roma, Italy), V. Sguera (INAF-IASF Bologna, Italy), J. Chenevez (DTU Space, Denmark), L. Sidoli (INAF-IASF Milano, Italy), A. Bazzano, L. Natalucci, P. Ubertini (INAF-IAPS Roma, Italy), A. Paizis (INAF-IASF Milano, Italy), E. Kuulkers (ESA/ESAC, Spain), A. J. Bird, P. A. Charles (Univ. of Southampton, UK)
on 15 Dec 2014; 14:32 UT
Credential Certification: mariateresa fiocchi (mariateresa.fiocchi@iaps.inaf.it)

Subjects: X-ray, Neutron Star, Transient

Referred to by ATel #: 6917, 8547, 10529

Recent observations from the on-going INTEGRAL Galactic Plane Scanning programme (PI: A. Bazzano) have detected increasing X-ray flux from the Be/X-ray binary pulsar GRO J1008-57, confirming the re-brightening detected by MAXI/GSC (ATel #6819).

The source was in the field of view of the IBIS and JEM-X instruments on-board INTEGRAL during revolutions 1483 (start time 2014-12-05T09:55 UTC) and 1485 (start time 2014-12-11T09:15). The hard X-ray fluxes, as detected by IBIS, have increased over the last week: in revolution 1483, GRO 1008-57 was detected with a flux of (21.6+/-1.7) mCrab in the 18-40 keV energy range (with an exposure time of 15 ks), later in revolution 1485 the source showed a flux of (53.4+/-1.9) mCrab (~4.7e-10 ergs cm-2 s-1) in the same energy range with an exposure time of 21 ks.

The JEM-X instrument detected GRO J1008-57 during revolution 1485, with a flux of 38.5 +/-3 mCrab (3-10 keV) and 70.5 +/-9 mCrab (10-25 keV), during a 4.9 ks effective exposure.

This is the third outburst peak observed from this source during the current X-ray activity which started in September (ATEL #6465, #6630, #6656, #6664, #6819). Multiple peaks are a complex morphology occurring in about 1/4 of the outbursts in Be/XRBs (e.g. Kretschmar et al., 2013, arXiv.1302.3434).

We will continue to monitor the source activity with INTEGRAL through the GPS programme until December 20th. Light curves and images can be found on the GPS webpages: http://gpsiasf.iasf-roma.inaf.it/