Follow up of the IceCube alerts with the Baikal-GVD telescope
Viktoriya Dik
on behalf of the Baikal-GVD collaboration Supervisors:
Shaybonov B. A., Suvorova O. V.
Content of the work
Baikal-GVD monitors online alerts from IceCube since August 2020.
The aim of this work is the search for correlation in direction and time of the signal in IceCube notifications with events
reconstructed from Baikal-GVD data for muon and cascade
modes.
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Baikal Gigaton Volume Detector
Effective volume for Baikal-GVD in 2021
— 0.4 kм3 for ν with E>100 TeV.
One cluster's volume is 0.05 km3.
Data transfer and processing scheme
See also B. Shaybonov talk
Time delays:
1. Few minutes from shore
2. Few hours in data processing ~ lake noises
Telescope
DAQ Storage
Processing Online
Analysis User
analysis
Quasi online Analysis
Deep
underwater Shore station Computing Center at Dubna
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Muon track and cascade reconstruction
The distribution of the
mismatch angles between MC neutrinos with an energy spectrum of E-2 and reconstructed muon trajectories.
Selection muon neutrino cuts reject events with Zen < 120º.
The distribution of events by angle between the simulated and reconstructed shower directions for one cluster.
For cascade reconstruction algorithm and cuts see also M. Shelepov talk
median angle ~ 1.27°
median angle ~ 4.5°
For muon reconstruction
algorithm see talks of D. Zaborov and G. Safronov
Sky locations of IceCube events in +/- 12 h from alert time
Seven start points of events with 92º<Zen<124º -> Muon
reconstruction is low efficient for one cluster mode
Source below horizonSource above horizon
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Three IC events tracks with the same visibility
The cascade ★ event rate is within
background estimate
Example: search for neutrinos around IC201120A Bronze by cascades
● Cuts for cascades on χ2, LLH, OM’s probability hit/
non hit, Nhit>7.
● Cone ψ < 5º between the direction of the event and the alert IC201120A.
weight = 1/ψ
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GVD cascade events with cone ψ< 5º in ±30 days around IC alerts in Aug 2020-Sep 2020
GVD cascade events with cone ψ< 5º in ±30 days around IC alerts in Oct 2020
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GVD cascade events with cone ψ< 5º in ±30 days around IC alerts in Nov 2020
GVD cascade events with cone ψ< 5º in ±30 days around IC alerts in Dec 2020 and Feb 2021
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Example: upper limit on fluence for IC201014A
For all clusters 2020 with cuts Data
Back
Track of IC201014A
Nbg = 0.44, Nobs = 1,
P-value =0.36, n90% = 4.36 Expos = 1787 TeV-1 cm2
E-2F = n90%/Expos = 2.44 . 10-3 Tev cm-2
Results by GVD cascade events
Publ. In A. D. Avrorin et al. HIGH ENERGY NEUTRINO FOLLOW UP WITH BAIKAL-GVD, Astronomy Letters 2021-02-01
For IC200926B, IC200929A, IC201014A Nobs= 1 in +/- 12 h.
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Summary
● The Baikal-GVD neutrino telescope has been monitoring alerts from IceCube neutrino telescope in quasi online regime.
● In cascade mode reconstruction the search of the concidences was done in cone 5° and ±12 h.
● For energy range 1TeV - 10PeV and assumption of E-2 spectrum in the source and equal fluence in all flavors the upper limits on neutrino fluence were found:
1÷2 GeV/cm2. The results were obtained for cascades and single clusters.
●
