IceCube-200614A

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

On 20/06/14 at  12:41:21.41 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 threshold astrophysical neutrino purity for Bronze alerts is 30% . This alert has an estimated false alarm rate of 1.48 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/134187_72386329.amon), more  
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 20/06/14
Time:  12:41:21.41 UT
RA: 33.84 (+4.77 -6.39 deg  90% PSF containment) J2000
Dec: 31.61( +2.75 -2.28 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 four Fermi-LAT 4FGL and 3FHL sources in the 90% containment region. The closest is 4FGL J0220.2+3246, 1.57 deg from the best fit location.  

Upon examination, this event appears to be a starting track event, where the neutrino interaction occurs inside the instrumented volume and the charge muon leaves the detector.  Starting events tend to have poorer angular resolution than standard through-going events. 

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

M. Doyle, A. Martin-Carrillo (UCD, Ireland)
V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)
J. Rodi (IAPS-Roma, Italy)
A. Coleiro (APC, France)
S. Mereghetti (INAF IASF-Milano, Italy)

on behalf of the INTEGRAL multi-messenger collaboration:
https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration

Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed
a search for a prompt gamma-ray counterpart of IceCube-200614A (GCN 27941
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 ).

At the time of the event (2020-06-14 12:41:21 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 75 deg with respect to the
spacecraft pointing axis. This orientation implies strongly suppressed
(15% of optimal) response of ISGRI, strongly suppressed (32% of
optimal) response of IBIS/Veto, and somewhat suppressed (64% of
optimal) response of SPI-ACS.

The background within +/-300 seconds around the event was very stable
(excess variance 1.1).

We have performed a search for any impulsive events in INTEGRAL SPI-
ACS (as described in [2]) data.

We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 2.7e-07 erg/cm^2 (within the
50% probability containment region of the source localization) for a
burst lasting less than 1 s with a characteristic short GRB spectrum
(an exponentially cut off power law with alpha=-0.5 and Ep=600 keV)
occurring at any time in the interval within 300 s around T0. For a
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and
Ep=300 keV), the derived peak flux upper limit is ~2.4e-07 (7.1e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

We report for completeness and in order of FAP, all excesses
identified in the search region. We find 3 likely background
excesses:

T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
-89.2 | 4.5 | 3.6 | 1.5 +/- 0.491 +/- 0.667 | 0.116
89.4 | 2.55 | 4 | 2.2 +/- 0.653 +/- 0.979 | 0.119
85.4 | 0.25 | 4.1 | 0.77 +/- 0.21 +/- 0.342 | 0.975

Note that FAP estimates (especially at timescales above 2s) may be
possibly further affected by enhanced non-stationary local background
noise. This list excludes any excesses for which FAP is close to
unity.

All results quoted are preliminary.

This circular is an official product of the INTEGRAL Multi-Messenger
team.

[1] Savchenko et al. 2017, A&A 603, A46 
[2] Savchenko et al. 2012, A&A 541A, 122S

J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team:

At the time of the neutrino candidate IceCube-200614A
(GCN 27941
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 ), Fermi was passing through the South Atlantic
Anomaly from 21 minutes prior to 4 minutes after the trigger
time; therefore the GBM detectors were disabled.

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

IceCube has performed a search for additional track-like muon neutrino events arriving
from the direction of IceCube-200614A (https://gcn.gsfc.nasa.gov/gcn3/27941.gcn3
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 ) in a time
range of 2 days centered on the alert event time (2020-06-13 12:41:21.410 UTC to 2020-06-15 12:41:21.410 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, one additional track-like event is found in spatial coincidence
with the 90% containment region of IceCube-200614A. We find that these data are consistent with atmospheric background expectations, with a p-value of 1.0. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/ dE = 5.2 x 10^-5 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 1 TeV and 500 TeV.

A subsequent search was performed to include the month of data prior to the alert event (2020-05-15 12:41:21.410 UTC to 2020-06-15 12:41:21.410 UTC). In this case, we report a p-value of 1.0, consistent with no significant excess of track-like events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of
 1.4 x 10^-4 TeV cm^-2 at the 90% CL.

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>.

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

We report an analysis of observations of the vicinity of the high-energy 
IC200614A neutrino event (GCN 27941
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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 2020-06-14 at 12:41:21.41 
UT (T0) with J2000 position RA =33.84 (+4.77 -6.39) deg, Decl. 
=31.61(+2.75 -2.28) deg 90% PSF containment. Five cataloged >100 MeV 
gamma-ray sources (The Fermi-LAT Collaboration 2019, 
arXiv:1902.10045
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 )�are located within the 90% IC200614A localization 
error. These are �4FGL J0159.0+3313, 4FGL J0202.4+2943, 4FGL 
J0203.7+3042, 4FGL J0205.2+3212 and 4FGL J0220.2+3246. Based on a 
preliminary analysis of the LAT data over the timescales of 1-day and 
1-month prior to T0, these objects are not significantly detected (> 5 
sigma).

We searched for �intermediate (days to years) timescale emission from a 
new gamma-ray transient source. Preliminary analysis indicates no 
significant (> 5 sigma) new excess emission (> 100 MeV), at the 
IC200614A best-fit 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 < 8e-10 ph cm^-2 s^-1 for 
~11-years (2008-08-04 / 2020-06-14 UTC), < 9e-9 (< 8e-8) ph cm^-2 s^-1 
for a 1-month (1-day) integration time before T0.

Within the 90% confidence localization�of the neutrino, ~2.7 deg offset 
from the best-fit IC200614A position, a >5 sigma excess of gamma rays, 
Fermi J0202.8+3132 was detected in an analysis of the integrated LAT 
data (> 100 MeV) between 2008-08-04 and �2020-06-14.�Assuming a 
power-law spectrum,�the�best-fit�localization is (J2000) RA: 
 �30.71,�Dec: 31.55 (0.16 deg 99% containment,�0.08 deg 
68%�containment), with best-fit spectral parameters flux =�(5 +/- 3)e-10 
ph cm^-2 s^-1 and index = 1.8 +/- 0.2. In a preliminary analysis of the 
LAT data over one day and one month prior T0, Fermi�J0202.8+3132 �is not 
significantly detected in the LAT data. A possible counterpart for 
Fermi�J0202.8+3132 is the BL Lac candidate object NVSSJ020242+313212 
(D'Abrusco et al. 2019, ApJS 242, 1), located 0.03 deg from the best-fit 
LAT localization.

Two additional�~4 sigma excess of gamma rays are detected within the 90% 
confidence localization�of IC200614A�in an analysis of the LAT data (> 
100 MeV) between 2008-08-04 and �2020-06-14. One is found at the 
best-fit localisation�RA= 32.69, Dec= 30.97 (0.15 deg 99% containment), 
and has best-fit spectral parameters flux = (4 +/- 3)e-10 ph cm^-2 s^-1 
and index = (1.8 +/- 0.2). The second one, at best-fit localisation�RA= 
35.91, Dec= 32.01 (0.2 deg 99% containment), has best-fit spectral 
parameters flux = (1.3 +/- 0.7)e-9 ph cm^-2 s^-1 and index = (2.2 +/- 
0.2). These excesses are located�~1.2 deg and�~1.8 deg away from the 
best-fit IC200614A position, respectively.�In a preliminary analysis of 
the LAT data over one day and one month prior to T0, they are not 
significantly detected in the LAT data.

All values include the�statistical uncertainty only.�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 <http://desy.de/>) 
and S. Buson (sara.buson at uni-wuerzburg.de 
<http://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.

Hugo Ayala (Penn State) reports on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration):

On 2020/06/14 12:41:21 UTC, the IceCube collaboration reported a
track-like very-high-energy event  that has a high probability of
being an astrophysical neutrino, IceCube-200614A. Location is at
RA: 33.84 (+4.77/-6.39 deg  90% PSF containment) J2000
Dec: 31.61 (+2.75/-2.28 deg 90% PSF containment) J2000
(GCN circular 27941
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 ).

We performed two types of analyses for the follow-up. The first is for
a steady source in archival data and the second is a search for a
transient source. We assume a power-law spectrum with an index of -2.3
for both analyses.

Search for a steady source in archival data:
The archival data spans from November 2014 to May 2018. We searched
inside the reported IceCube error region.
The most significant location, with p-value 3.02e-4 (8.27e-2 post-trials),
is at RA 35.51 deg, Dec 33.55 deg (��0.16 deg 68% containment) J2000.
We set a time-integrated 95% CL  upper limit on gamma rays at the
maximum position of:

E^2 dN/dE = 3.85e-13 (E/TeV)^-0.3 TeV.cm^-2.s^-1

Search for a transient source.

Since the IceCube event fall inside the HAWC field of view,
we report on the result for the transit of the IceCube
position.

Data acquisition started on 2020/06/13 18:10:07 UTC and ended
2020/06/14 18:32:13 UTC.
The most significant location, with p-value 1.35e-3  (3.20e-1 post-trials),
is at RA 38.63 deg, Dec -30.55 deg (��0.09 deg 68% containment) J2000.
We set a time-integrated 95% CL upper limit at the position of
maximum significance of:

E^2 dN/dE = 1.46e-11 (E/TeV)^-0.3 TeV.cm^-2.s^-1

HAWC is a very-high-energy gamma-ray observatory operating in Central
Mexico at latitude 19 deg. north. Operating day and night with over
95% duty cycle, HAWC has an instantaneous field of view of 2 sr and
surveys 2/3 of the sky every day. It is sensitive to gamma rays from
300 GeV to 100 TeV.