IceCube-220202A

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

On 2022-02-02 at 11:48:38.59 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Gold alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 1.925 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/136241_22093816.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2022-02-02 
Time: 11:48:38.59 UTC
RA: 21.36 (+1.10, -0.77 deg  90% PSF containment) J2000
Dec: -3.88 (+0.42, -0.64 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.

There are no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0124.8-0625 at RA: 21.22 deg, Dec: -6.43 deg (2.56 deg away from the best-fit event position).

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

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

IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-220202A (https://gcn.gsfc.nasa.gov/gcn3/31543.gcn3
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 ) in a time range of 1000 seconds centered on the alert event time (2022-02-02 11:40:18.590 UTC to 2022-02-02 11:56:58.590 UTC) during which IceCube was collecting good quality data. Excluding the event  that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-220202A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-220202A ranges from 2.4e-01 to 3.3e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 4e+02 GeV and 2e+05 GeV.

A subsequent search was performed including 2 days of data centered on the alert event time (2022-02-01 11:48:38.590 UTC to 2022-02-03 11:48:38.590 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-220202A ranges from 2.5e-01 to 3.4e-01 GeV cm^-2 in a 2 day time window.

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<mailto:roc@icecube.wisc.edu>.

[1] IceCube Collaboration, R. Abbasi  et al., ApJ 910 4 (2021)

S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and J. 
Sinapius (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC220202A neutrino event (GCN 31543
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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 2022-02-02 11:48:38.59 UTC 
(T0) with J2000 position RA = 21.36 (+1.10, -0.77) deg, Decl. = -3.88 
(+0.42, -0.64) deg 90% PSF containment. No cataloged gamma-ray sources 
are found within the 90% IC220202A localization error (The Fourth 
Fermi-LAT catalog DR3; The Fermi-LAT collaboration 2022, arXiv:2201.11184
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 ).

We searched for the existence of intermediate (months to years) 
timescale emission from a new gamma-ray transient source. Preliminary 
analysis indicates no significant (>5sigma) new excess emission (> 100 
MeV) at the the IC220202A best-fit position. Assuming a power-law 
spectrum (photon index = 2.0 fixed) for a point source at the IC220202A 
best-fit position, the >100 MeV flux upper limit (95% confidence) is < 
2.4-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 / 2022-02-02 UTC), < 
3.7e-9 (< 5.7e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time 
before T0.

Since Fermi normally operates in an all-sky scanning mode, regular 
monitoring of this source will continue. For these observations the 
Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de) 
and S. Buson (sara.buson at uni-wuerzburg.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.