Low GeV neutrino follow-up oftransient events with IceCube
Karlijn Kruiswijk on behalf of the IceCube Collaboration

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Content●●●

Current GeV selection
Transient follow-up
Improvements to the GeV selection

970 MeV𝜈eLow GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Observing neutrinos in IceCube
Cherenkov radiation can beobserved by 5160 PMTs
Optimized for TeV neutrinos
DeepCore optimized for sub-TeVneutrinos●●More sensitive PMTs
PMTs closer together

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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for GRB221009A

The ELOWEN selection
Lowest energy for observing single
neutrino events
Specialized for 0.5 - 5 GeVConsists of several hard cuts on
low-level variables to remove bothnoise and high-energy events

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

4Multi-messenger follow up with ELOWEN
Compare number of neutrino
candidates during transient event tobackground

Transient●●●

Solar ﬂare searches
Gravitational wave follow up○ Catalog search of O1-O3○ Currently ongoing for O4
GRB 221009A

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Hits →Search for neutrinos from transients:

Time →5

Gravitational wave follow-up
Neutrinos can come from p-n
interactions.
2 Time Windows:●●± 500 s around merger time
3 s starting at merger time
○only for BNS and NSBH

Compare to background distribution: data when no transient
events were detected (GRB, GW, solar ﬂares)
Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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O1-O3 Follow up
72 merger candidates
Results consistent with background
Upper limits:
1.2⋅104 cm-2 for 3s TW● 3.9⋅104 cm-2 for 1000s TW●

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

arXiv:2105.13160

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O4 Follow up
Currently ongoingOﬄine analysis: no pointing tohelp with follow up
2 NSBH alerts: both 0 neutrinos
in 3 s Time Window
So far no signiﬁcant deviationfrom background

Low GeV neutrino follow-up of transient events with IceCubeICRC2023 Satellite workshop

PoS ICRC2023 1571: ArXiv 2307.15902

8GRB 221009A:
The Brightest Gamma Ray Burst ever observed
1.

Brightest GRB Observed by Fermi GBM andFermi LAT

2.

Afterglow reported by Swift as a bright X-ray
and optical transient

3.

Konus-Wind measured the isotropic equivalent
gamma-ray energy :~1.2⋅1055 erg

4.

Detected by LHAASO within 3000 s:○○

Credit: NASA/DOE/Fermi LAT
Collaboration

Over 64,000 photons
Energies between 0.2 TeV and 7 TeV
Credit: Adam Goldstein, USRALow GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop[1] GCN32636 and GCN32642, [2] GCN32632,[3] arXiv:2302.13383, [4] arXiv:2306.06372

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GRB221009A follow-up●Together with other IceCubesearches○●Time windows:○●

Covering MeV to PeV
T0[-200s,+2000s] and T0[-500s,500s]

Search for quasi-thermal neutrinos○p-p /p-n interactions

No signiﬁcant excess of neutrinos
foundCan test theoretical model
Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

IceCube GRB 221009 analysis:ApJL 946 L26 (2023)

10Quasi-thermal Decouplingand Collision models
Created from p-n interactions:●Decoupling model○●

Neutrons decouple from jetCollision model○

Neutrons collide with subsequent
outﬂowDecoupling
model only

Decoupling model tested with ELOWEN

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Reference: ApJL 941 L10 (2023)

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Further plans for follow-up●●Continue with O4More Gamma Ray Burst follow-up○●

Stacked over diﬀerent populations

Other (short) transient events

Plan to further improve the elowen selection for better sensitivity

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

12Improving the ELOWEN selection
Right now limited by detector noise, nodirection reconstruction present.
Currently working to improve (withdata science tools)●Noise reduction○○●

Combining ﬁlters
Specialising ﬁlter stages

970 MeV𝜈eDirection reconstruction○Zenith direction

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Noise reduction
Combining all ﬁltering stages insteadof just hard cuts
Flexibility with global ﬁltering
Dimensionality reduction: separation
already visible with t-SNE
This allows us to see what(combination of) variables is best forﬁltering
Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Noise reduction: specialising ﬁlters
Special ﬁlters called NoiseEngine: ﬁlteringout detector noise based on causality
between hits
Parameters:●●●●

Number of hit-pairs necessary
Minimum velocity
Maximum velocity
Time window

Combining diﬀerent settings with a boosted
decision tree
Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Noise reduction: specialising ﬁlters
Result:Using 109 (out of 4500 possible) ﬁlters●●Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

0.17% of noise passes
39% of neutrinos pass16

Directional reconstruction
Does not yet exist at this energy level:interactions are too small compared tostring spacing
PMT spacing and PMT position allow forrough distinction between up- anddown-going neutrinos
Data used:●

6 PMTs surrounding PMT of 1st hit○Detections and delays of hits

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Directional reconstruction
2 Boosted decision trees: for up- and downgoing●●

Able to reconstruct 60%
Balanced accuracy: 77%

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Conclusion & Prospects●

Transient events can be followed up with ELOWEN○○○●

Improvements planned in noise reduction○○●

GRB221009A
O4 follow up ongoingMore searches planned in the future
Combination of ﬁltering steps
More precise ﬁltering

Direction reconstruction of GeV neutrinos○○Zenith direction
Using detector conﬁguration

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

19Thanks

Thank you forMerci
Tack
ありがとう
Grazie謝謝
listening!
Danke감사해
요

TakDankjewel

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

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Decoupling model
Model by Kohta Murase
only works whenAssumes

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Reference: ApJL 941 L10 (2023)

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All upper limits GRB221009A

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Reference: ApJL 946 L26 (2023)

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Diﬀerential upper limits GRB221009A

Low GeV neutrino follow-up of transient events with IceCube
ICRC2023 Satellite workshop

Reference: ApJL 946 L26 (2023)

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