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INTEGRAL/SPI observation of V404 Cyg: hard X-ray emission extends up to 650 keV.

ATel #7693; J. P. Roques (IRAP/CNRS), E. Jourdain (IRAP/CNRS), E. Kuulkers (ESAC/ESA)
on 23 Jun 2015; 08:43 UT
Credential Certification: Elisabeth Jourdain (ejourdain@irap.omp.eu)

Subjects: X-ray, Gamma Ray, Black Hole, Transient

Referred to by ATel #: 7694, 7695, 7702, 7708, 7718, 7721, 7722, 7734, 7740, 7758, 7759, 7959

Following the discovery of a new outburst of V404 Cyg(GS2023+338, GCN #17929 and Atel #7646), INTEGRAL observations have been triggered and shown that the source exhibits an intense hard X-rays activity (Atel #7662) We report on INTEGRAL/SPI spectral results on this source during revolution 1554 (from 2017-06-17 20:17 until 2015-06-20 00:03). The mean spectrum of the source extends up to 650 keV and can be tentatively described by a Comptonization law with kT=30 keV, tau= 2, with a reflection factor fixed to 1, plus an additional cutoff powerlaw component: ?= 1.6, Ecut= 300 keV. The 20-200 keV flux is 3.6 E-8 ergs/cm2/s and the 200-650 keV flux is 4.0 E-9 ergs/cm2/s The high energy component is also required at the peak intensity (20-200 keV flux of 2.4 E-7 ergs/cm2/s, 200-650 keV flux of 2.4 E-08 ergs/cm2/s, averaged over a 3 ks exposure). More refined work is in progress.