Search for neutrino counterparts of LIGO/Virgo gravitational-wave events Unatlokov I.B. Institute for Nuclear Research RAS 17th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2021) Gravitational Wave Transient Catalogs GWTC-1 Run O1 Run O2 12.09.2015 — 19.01.2016 30.11.2016 — 25.08.2017 GW150914 GW170104 GW170814 GW151012 GW170608 GW170817 GW151226 GW170729 GW170818 GW170809 GW170823 GWTC-2 Run O3 01.04.2019 — 30.09.2019, 01.11.2019 — 27.03.2020 GW190930_133541 GW190630_185205 GW190517_055101 GW190929_012149 GW190720_000836 GW190514_065416 GW190924_021846 GW190719_215514 GW190513_205428 GW190915_235702 GW190708_232457 GW190512_180714 GW190910_112807 GW190707_093326 GW190503_185404 GW190909_114149 GW190706_222641 GW190426_152155 GW190828_065509 GW190701_203306 GW190425 GW190828_063405 GW190620_030421 GW190424_180648 GW190814 GW190602_175927 GW190421_213856 GW190803_022701 GW190527_092055 GW190413_134308 GW190731_140936 GW190521_074359 GW190413_052954 GW190728_064510 GW190521 GW190412 GW190727_060333 GW190519_153544 GW190408_181802 2 Search for high-energy neutrinos (GeV and above) from GW-events The detection of gravitational waves and high-energy neutrinos from the same sources will make it possible to find a connection between the dynamics of gravitating objects and the properties of relativistic flows. The direction of a muon, produced in the reaction of interaction of a muon neutrino with matter, strongly correlates with the direction of a neutrino. At sufficiently high neutrino energies, the direction to the astrophysical object can be found with an accuracy of 2 degrees. Since the directions to the source of gravitational waves can be reconstructed with an accuracy of tens to hundreds of square degrees, the joint observation of gravitational waves and neutrinos can significantly improve the localization of the source, making subsequent electromagnetic observations easier. 3 Baksan Underground scintillation telescope BUST BUST counter 11 m 11 Since there is no significant background from the zenith angles more than 100º it is safe to say that muons from the lower Muon neutrinos traveling through the rock hemisphere are the result of neutrino- may interact with nucleons to create matter interaction under the telescope. The energetic muons: ν + N → µ + X µ overall uncertainty of the neutrino direction for the BUST is ≈ 5º. Separation of arrival directions between up and down hemispheres is made by time-of-flight method. 4 Baksan Underground scintillation telescope • The scintillator CnH2n+2 (n ≈ 9). • The total mass of scintillator is 330 t (3180 counters). • Three lower horizontal layers (the interior) -130 t, 1200 counters. • Counter's threshold: inner planes – 8 MeV; outer planes –10 MeV. • The radiation length for scintillator is 47 g/cm2. 2 • heff = 850 hg/cm . • (Eth)eff = 0.22 TeV. • The angular resolution of the telescope is ≈1.6º. 5 Search of counterparts 1. Search for neutrino events within ± 500s* from the moment of the GW-event. 2. Check if the localization of the GW-event is at least partially in the field of view of the BUST. 3. If GW localization and field of view of the BUST do not overlap – processing is finished. If they overlap – neutrinos are sought in the region of GW localization. If there is a neutrino event, а counterpart is found. 4. If there are no neutrino events, the maximum and minimum upper limits on the integral flux are calculated within the overlap region of the GW localization and the BUST field of view. * Bounding the time delay between high-energy neutrinos and gravitational-wave transients from gamma-ray bursts. Astropart. Phys., 35, 1, 2011; arXiv:1101.4669 6 Field of view of the BUST Localization of the source on the skymap is checked against the field of view of BUST There is no overlap There is overlap GW190930_133541 GW190527_092055 GW190924_021846 GW190731_140936 7 Search for points at which the area of the BUST has minimum and maximum values 2 2 Localization of the event GW190909_114149, Smin = 74.78 м , Smax = 215.91 м 8 Data processing Limits on fluxes 푛90 퐼푙푖푚 = 푆푒푓푓 퐸휈, 휃, 휙 = 휎휈푁 퐸휈 ⋅ 푁푁 퐸푚푎푥 ׬ 퐼 퐸휈 휀 ⋅ 푆푒푓푓 퐸휈 푑퐸휈 퐸푚푖푛 푛 90 퐸1 퐼 퐸휈, 휃, 휙 = 푛90 ׬ 퐼 퐸휈 퐸휈푑퐸휈 휀 ⋅ 푆 퐸 , 휃, 휙 퐸2 푒푓푓 휈 퐹 = 푙푖푚 퐸푚푎푥 n90 = 2.3, ε = 0.84 ׬ 퐼 퐸휈 휀 ⋅ 푆푒푓푓 퐸휈 푑퐸휈 퐸푚푖푛 Telescope area in different zenith, azimuth angles (muon crosses 3 or more planes) 2 STmin = 72 m 2 9 STmax = 217 m Limits on fluxes (GWTC-2) Muon neutrinos Muon antineutrinos −2 −2 −2 −2 GW event Fmax, cm Fmin, cm Fmax, cm Fmin, cm GW190929_012149 151.9 54.4 299.0 107.1 GW190915_235702 138.3 78.9 272.3 155.3 GW190910_112807 147.1 56.5 289.7 111.3 GW190909_114149 145.8 50.5 287.1 99.4 GW190828_065509 146.6 75.0 288.7 147.7 GW190828_063405 147.1 94.1 289.7 185.4 GW190803_022701 138.3 89.3 272.3 175.8 GW190731_140936 135.6 50.7 267.1 99.8 GW190728_064510 141.2 69.9 278.0 137.7 GW190727_060333 137.3 66.2 270.3 130.3 GW190720_000836 144.2 66.7 283.9 131.4 GW190719_215514 145.6 52.0 286.7 102.4 GW190708_232457 146.9 53.5 289.2 105.4 GW190707_093326 145.8 50.9 287.1 100.3 GW190706_222641 151.9 72.1 299.0 141.9 GW190701_203306 78.2 64.7 154.0 127.4 GW190630_185205 137.2 67.5 270.2 133.0 GW190620_030421 146.9 69.7 289.2 137.3 GW190602_175927 137.4 51.5 270.5 101.3 10 Limits on fluxes (GWTC-2) Muon neutrinos Muon antineutrinos −2 −2 −2 −2 GW event Fmax, cm Fmin, cm Fmax, cm Fmin, cm GW190527_092055 137.7 51.1 271.2 100.7 GW190521_074359 142.1 51.5 279.8 101.4 GW190521 146.6 73.6 288.7 144.9 GW190519_153544 150.2 56.0 295.7 110.3 GW190517_055101 138.7 51.8 273.1 102.0 GW190514_065416 144.0 51.8 283.5 102.1 GW190513_205428 144.1 64.9 283.8 127.8 GW190512_180714 140.8 64.7 277.3 127.3 GW190503_185404 99.4 57.0 195.7 112.3 GW190426_152155 140.0 55.9 275.6 110.1 GW190425 148.1 51.9 291.6 102.2 GW190424_180648 150.2 50.9 295.7 100.2 GW190421_213856 138.2 51.7 272.1 101.8 GW190413_134308 142.9 65.2 281.3 128.4 GW190413_052954 141.6 60.0 278.8 118.2 GW190412 136.4 63.9 268.5 125.8 GW190408_181802 144.1 62.5 283.8 123.0 GW190930_133541 Out of FOV GW190924_021846 Out of FOV 11 GW190814 Out of FOV Limits on fluxes GWTC-1 Muon neutrinos Muon antineutrinos −2 −2 −2 −2 GW event Fmax, cm Fmin, cm Fmax, cm Fmin, cm GW150914 109.3 52.9 215.1 104.2 GW151012 146.9 50.8 289.5 100.0 GW151226 148.1 51.8 291.6 101.9 GW170104 144.0 51.6 283.6 101.6 GW170608 138.3 70.6 272.4 139.1 GW170729 146.5 56.0 288.5 110.3 GW170809 103.2 58.3 203.2 114.8 GW170814 64.5 54.9 126.9 108.1 GW170823 146.5 52.9 288.5 104.2 GW170817 Out of FOV GW170818 Out of FOV First confirmed neutron star-black hole mergers Muon neutrinos Muon antineutrinos −2 −2 −2 −2 GW event Fmax, cm Fmin, cm Fmax, cm Fmin, cm GW200105_162426 146.9 56.6 289.2 111.5 GW200115_042309 146.5 53.6 288.5 105.5 No counterparts were found 12 Conclusions • Possible detection of neutrinos from sources of gravitational waves will significantly improve the localization of the source, thereby making further electromagnetic observations easier. • Until now, no neutrino events from sources of gravitational waves have been detected. 13 Thanks for your attention!.