INTEGRAL follow-up of IceCube HESE 128340 58537957

ATel #9391; V. Savchenko (APC, Paris, France) , C. Ferrigno (ISDC, University of Geneva, CH), P. Ubertini, A. Bazzano, L. Natalucci (INAF, IAPS-Roma, Italy), S. Mereghetti (INAF, IASF-Milano, Italy), P. Laurent (CEA, Saclay, France), E. Kuulkers (ESAC/ESA, Madrid, Spain)
on 21 Aug 2016; 12:24 UT
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Credential Certification: Volodymyr Savchenko (savchenk@in2p3.fr)

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On 2016-08-14 21:45:54 the IceCube detector has observed a high-energy neutrino likely of astrophysical origin, HESE 128340 58537957.
The location of the event is contained in a circle of 1.5 degree radius (systematic and statistical uncertainty, 90% confidence) centered at RA=199.3100 Dec=-32.0165, assuming that the interaction in the IceCube detector was track-like.

INTEGRAL has performed an observation of the neutrino localization region, starting 36 hours after the neutrino detection from 2016-08-16 09:43:41 UTC to 2016-08-17 16:19:07 UTC, corresponding to a total on-target time of 100 ks.

We have investigated the data collected by INTEGRAL IBIS and JEM-X without finding any significant new source in IBIS/ISGRI data between 20 and 200 keV within the localization area of HESE 128340 58537957. In the JEM-X 3-35 keV mosaic image corresponding to the whole observation period we identify an excess with SNR of 4.2. We have split the observation in two periods of equal duration, and verified that this excess is not detected with SNR more than 4 in any of them. The probability of this excess happening randomly in the region of interest is 25%.

We derived an upper limit on the flux of any new source in the 90% localization region of the HESE 128340 58537953, averaged over the observation, of 6 mCrab (1.8x10^-10 erg/cm2/s) in 3-35 keV, 3 mCrab (3.7x10^-11 erg/cm2/s) in 20-60 keV , and 7 mCrab (8.2x10^-11 erg/cm2/s) in 60-200 keV.

We have also searched for new sources in the whole area covered by the observation with sensitivity no worse than 4 times the deepest target sensitivity: 16 degree diameter for JEM-X (3-35 keV) and 30 degrees for ISGRI (20-200 keV). We did not find any unidentified source with SNR larger than 5.

INTEGRAL/SPI-ACS observation at the time of the neutrino detection is reported in GCN #19828.