IceCube-200512A

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-200512A (https://gcn.gsfc.nasa.gov/gcn3/27719.gcn3
Loading...
 
 ) in a time
range of 2 days centered on the alert event time (2020-05-11 07:31:27.750 UTC to 2020-05-13 07:31:27.750 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, two additional track-like events are found in spatial coincidence
with the 90% containment region of IceCube-200512A. 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 = 4.1 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 1 PeV.

A subsequent search was performed to include the month of data prior to the alert event (2020-04-12 07:31:27.750 UTC to 2020-05-13 07:31:27.750 UTC). In this case, we report a p-value of 0.05, 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
 9.4 x 10^-5 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. Buson (Univ. of Wuerzburg) and S. Garrappa (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy IC200512A neutrino event (GCN 27719
Loading...
 
 ) 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 2020-05-12 07:31:27.75 UT (T0) with J2000 position RA = 295.18 (+1.72, -2.26) deg, Decl. = 15.79 (+1.26, -1.29) deg 90% PSF containment. No cataloged >100 MeV gamma-ray sources are located within the 90% IC200512A localization error.

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) within the IC200512A 90% confidence localization. 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 < 7e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 2020-05-12 UTC), < 9e-9 (< 1e-7) 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 this source the Fermi-LAT contact persons are S. Buson (sara.buson at uni-wuerzburg.de) 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.

At the time of IceCube-200512A (GCN 27719
Loading...
 
 ), 
Fermi was passing through the South Atlantic Anomaly 
from 7.5 minutes prior until 13.3 minutes after the trigger time; 
therefore the GBM detectors were disabled.

Simeon Reusch, Robert Stein and Anna Franckowiak (DESY) report, 

On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: 

We observed the localization region of the neutrino event IceCube-200512A (Lagunas et. al, GCN 27719
Loading...
 
 ) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g-band and r-band beginning at 2020-05-12T09:16:17.700 UTC, approximately 1.7 hours after event time. We covered 9.3 sq deg, corresponding to 99.1% of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag.

The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019).

No promising source candidates were identified.

We note that the reported neutrino localization region lies at low galactic latitude. Given the high galactic extinction, our search was not sensitive to extragalactic objects.

Observations of this region will continue as part of routine survey operations.

ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019).

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-200512A (GCN 27719
Loading...
 
 ).

At the time of the event (2020-05-12 07:31:27 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 137 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed (2.8% of optimal) response of ISGRI, somewhat suppressed
(55% of optimal) response of IBIS/Veto, and strongly suppressed (36%
of optimal) response of SPI-ACS.

The background within +/-300 seconds around the event was very stable
(excess variance 1.2).

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 4.9e-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 ~4.6e-07 (1.2e-07)
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: 1 tentatively associated
excess:

T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
-0.501 | 0.35 | 3.7 | 1 +/- 0.302 +/- 0.488 | 0.00748

1 possibly associated excess:

T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
-4.13 | 0.9 | 3.7 | 0.651 +/- 0.188 +/- 0.317 | 0.0214

3 likely background excesses:

T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
-81.8 | 2.1 | 3.7 | 0.434 +/- 0.123 +/- 0.211 | 0.179
23.4 | 0.25 | 3.3 | 1.1 +/- 0.357 +/- 0.536 | 0.937
-190 | 0.5 | 4.2 | 0.987 +/- 0.252 +/- 0.481 | 0.955

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

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

On 20/05/12 at 07:31:27.76 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 2.61 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/134081_58268464.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 20/05/12 
Time: 07:31:27.76 UT
RA: 295.18 (+1.72 -2.26 deg 90% PSF containment) J2000
Dec: 15.79 (+1.26 -1.29 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 4FGL sources inside the 90% localization region. The closest source is 4FGL J1947.1+1729 located at RA 296.78 deg and dec 17.49 deg  (at a distance of 2.28 degrees from the best-fit location).

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