IceCube-190629A

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On 29/06/19 at 19:24:15.12 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream.  The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 0.64 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/132768_5390846.amon), more  sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 29/06/19
Time:  19:24:15.12 UT
RA:  27.22 (Dec value too close to pole for accurate error on RA) J2000
Dec: 84.33 (+4.95 -3.13 deg 90% PSF containment) J2000

We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

Two gamma-ray sources listed in the 4FGL Fermi-LAT catalog are located within 2 deg of the best-fit candidate neutrino position. The sources are 4FGL J0151.3+8601 and 4FGL J0151.3+8601, both associated with BL Lac objects, and are located 1.5 and 1.7 deg away from the best-fit position, respectively. Both sources are also listed in the Fermi 3FHL catalog as 3FHL J0249.7+8434 and 3FHL J0148.4+8601, respectively.  A total of 9 sources listed in the 4FGL catalog are contained in a 4 deg radius from the best-fit position, which approximately corresponds to the 90% containment radius of the event.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu

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Erik Blaufuss                      email: blaufuss@umd.edu
Department of Physics       http://icecube.umd.edu/~blaufuss
University of Maryland       Phone: 301-405-6077
College Park, MD 20742   Office: PSC 2208E
"Any chance collision, and I light up in the dark."
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J. Wood (NASA) and R. Hamburg (UAH) report on behalf of the
Fermi-GBM Team:

For the IceCube high-energy neutrino candidate event 190629A
(GCN 24910
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 ), at the event time Fermi-GBM was observing the
reported neutrino location at:

RA = 27.22 (Dec value too close to pole for accurate error on RA) J2000
DEC = 84.33 (+4.95/-3.13 deg 90% PSF containment) J2000

There was no Fermi-GBM onboard trigger around the event time
of the neutrino candidate. An automated, blind search for gamma
-ray transients below the onboard triggering threshold in Fermi-
GBM also identified no counterpart candidates +/- 1 hour of event
time.

The GBM targeted search, the most sensitive, coherent search for
GRB-like signals, was run from +/-30 s around the neutrino candidate
time. The most significant result from this search was found T0+12 s
on the longest timescale of ~10 s and was best fit with the "normal"
spectral template described in arXiv:1612.02395
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 . The GBM localization
is centered at RA, DEC = (123.8, 25.0) with a 90% credible region
spanning 10,084 square degrees. Modelling the neutrino localization
as a Gaussian with a width of 3 degrees and centered at the
coordinates reported by IceCube, we find the spatial consistency
between the localizations to be 1.8%. We therefore consider this
signal likely unrelated to IceCube-190629A.

We set upper limits on impulsive gamma-ray emission. Using the
representative soft, normal, and hard GRB-like templates
(arXiv:1612.02395
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 ), we report the following 3 sigma flux upper limits
over 10-1000 keV (in units of 10^-7 erg/s/cm^2):

Timescale  Soft     Normal   Hard
------------------------------------
0.128 s:     7.6e-07  8.6e-07  1.5e-06
1.024 s:     1.4e-07  2.7e-07  6.1e-07
8.192  s:     6.8e-08  1.3e-07  2.6e-07

S. Garrappa (DESY-Zeuthen, DE), S. Ciprini (INFN Roma Tor Vergata, ASI, IT) and S. Buson (Univ. of Wuerzburg, DE; UMBC, USA) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy IC190629A neutrino event (GCN 24910
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 ) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2019-06-29 19:24:52 UTC (T0) with J2000 position RA = 27.22 (error not provided) deg, Decl. = -84.33 (+4.95 -3.13) deg 90% PSF containment. 

We searched for the existence of intermediate (months to years) timescale emission from a new gamma-ray transient source at the best-fit IC190629A position. Preliminary analysis indicates no significant (>5sigma) new excess emission (0.1 - 300 GeV) at the best-fit IC190629A position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limit (95% confidence) is < 3e-10 ph cm^-2 s^-1 for ~10.9-years (2008-08-04 / 2019-06-20 UTC) and < 7e-9 (< 5e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.

Several cataloged gamma-ray sources are found within 5 degree from the best-fit IC190629A position. None of these is significantly detected in the 1-month and 1-day scale integration time before T0. Analysing the Fermi-LAT data in the vicinity of IC190629A, we find evidence for a new gamma-ray source, significantly (>5 sigma) detected in the 10.9-years time interval, and also on shorter timescales as reported in ATel #12902. It is positionally consistent with the blazar S5 0532+82, and located 6.5 degrees from the best-fit position of IC-190629A.

Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this source the Fermi-LAT contact person are S. Ciprini (stefano.ciprini.asdc at gmail.com) and S. Garrappa (simone.garrappa at desy.de).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.