IceCube-Cascade 240714A: two coincident track-like events detected by IceCube
ATel #16708; Justin Vandenbroucke (University of Wisconsin - Madison), Marcos Santander (University of Alabama - Tuscaloosa), Jessie Thwaites (University of Wisconsin - Madison), Alicia Mand (University of Wisconsin - Madison), Samuel Hori (University of Wisconsin - Madison), Aswathi Balagopal V. (University of Wisconsin - Madison), Abhishek Desai (NPP Fellow, NASA GSFC)
on 16 Jul 2024; 01:15 UT
Credential Certification: Justin Vandenbroucke (justin.vandenbroucke@wisc.edu)
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search [1] for track-like muon neutrino events arriving from the direction of IceCube-Cascade 240714A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/139644_63900267.amon) in a time range of 1000 seconds centered on the alert event time (2024-07-14 14:49:18.540 UTC to 2024-07-14 15:05:58.540 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-Cascade 240714A. We accordingly derive a p-value of 1.00. 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-Cascade 240714A ranges from 1.0e+01 to 2.2e+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 range 4e+04 GeV to 4e+06 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2024-07-13 14:57:38.540 UTC to 2024-07-15 14:57:38.540 UTC). In this search, we detect two track-like events in spatial coincidence with one another and with the original cascade-like event, resulting in a pre-trial p-value of 0.007. Due to the coincident events identified in this search, we encourage follow-up observations. The best-fit direction for a potential source producing the cascade and two tracks is RA: 243.28 deg, Dec: -36.61 deg (J2000), with an estimated error radius of 0.3 deg at 90% containment. The nearest 4FGL-DR4 source to this best-fit direction is 4FGL J1616.5-3500 (RA: 244.13 deg, Dec: -35.00 deg J2000), at an angular distance of 1.7 deg.
Properties of the two coincident track events are shown in the table below.
dt(s) | RA(deg) | Dec(deg) | Angular uncertainty(deg)
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-5049 | 243.09 | -36.89 | 0.43
49974 | 243.45 | -36.30 | 0.43
where:
dt = Time of track event minus time of the cascade event (sec)
Angular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area.
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.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
