Internati national onal Symposium mposium on reveal alin ing g the histor ory of the univer erse e with under ergr ground ound particle le and nucle lear ar resear arch h 2019 March h 9 th th , 2019 9 at Aoba a Science ience Hall, Tohok oku u Univer ersity, ity, Sendai dai
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Tevatron, Pevatron e+e- e+e- e+e- e+e- 3
Catch the cosmic messengers – only interact weakly during “propagation” • Penetration power • Pointing capability 4
p+ interactions or p+p interaction with matter FLUX [(GeV cm 2 sec sr) -1 ] Atmospheric to astrophysical transition ~10TeV-100TeV Atmospheric neutrinos IceCube found the cosmic neutrino flux Astrophysical close to WB limit: neutrinos https://journals.aps.org ? ~10TeV to PeV or EeV ?? /prd/pdf/10.1103/Phys RevD.59.023002 5 ENERGY [eV]
Hadronic “ n creation” only need simple ingredients 𝟑𝟏 𝑭 𝑸 ≈ 𝟐 𝟐 𝑭 𝝃 ≈ 𝟑 𝑭 𝜹 • Cosmic-ray and target spectra in source – Via pp or p interaction 𝜌 + 𝑢𝑝 𝜌 − ratio at source is target (model) dependent • Directly accompanying partners – gamma-ray from neutral pions ( 𝜌 0 → 𝛿𝛿 but >TeV 𝛿 will cascade down to <TeV via 𝛿𝛿 𝐷𝑁𝐶 → 𝑓 + 𝑓 − → 𝛿 𝐽𝐷 , 𝛿 𝑡𝑧𝑜𝑑 process) – parent cosmic-rays (p, nuclei) alternate models: 𝜈 dumping neutron decay • Indirectly accompanying partners – radiations, radio, optical, x-ray... – Gravitational waves Multi-messenger ! 6
𝐅 𝛏 ≈ 𝟐 neutrino energy range: 10-100 TeV 𝟑𝟏 𝐅 𝐐 Δ 𝟐𝟏𝟏 − 𝟐𝟏𝟏𝟏 𝒇𝑾 (𝚫~𝟐) : non-relativistic ቐ : e.g. AGN : e.g. GRB Need to satisfy Hillas condition 𝐹 p < 𝑎𝑓𝐶𝑆𝛾 Typical pɤ candidate sources such as AGN and GRB exhibit rapid time variation! → Multimessenger observation → Their temporal and spatial coincidence 7
Neutrino and gamma-ray spectra copy CR spectra Induces too much <TeV Background gamma Need to satisfy Hillas condition 𝐹 p < 𝑎𝑓𝐶𝑆𝛾 galaxy cluster how to distinguish pp and pɤ Spectral shape? Association with candidate object? Detection of anti nu e from pi (mu) minus decay could be the key! 8
Northern hemisphere BAIKAL-GVD ANTARES Lake Bikal Mediterranean Ocean BAIKAL-GVD Phase1 (864 PMTs by 2018) 1/100km 3 IceCube South Pole ☞ GVD Phase 1(2304 PMTs in 2021) ☞ BAIKAL GVD full scale Glacial ice ANTARES (12lines 882PMTs) 1/100km 3 ☞ KM3NET Phase 1 ☞ KM3NET 2.0 IceCube (86lines 5160PMTs) 1km 3 ☞ IceCube-Gen2 Phase 1 ☞ IceCube-Gen2 Southern hemisphere 9
http://icecube.wisc.edu 10
Detection Principle Array of photomultiplier tubes in a dark transparent material Cherenkov light Charged m l , ν l ν l t Particles W, Z e Digitized hadronic shower Waveform n 11
The IceCube Detector neutrino energy: 1TeV-100EeV • Spacing: Strings 125 m, DOMs 17 m neutrino energy: 5GeV-100GeV • Spacing: Strings ~70 m, DOMs 7 m 12
IceCube Flavor Identifications Up-going muon track event m ν l l , n m CC only t ν l W, e Z hadronic shower 〜 100TeV Casca cade e events nts All except n m CC Tau flavor signatures (not covered in this talk) E dep ~130TeV PRL 111 (2013) 021103 Phys. Rev. D 84, 072001 (2011) 13
14 Energy Range for IceCube/DeepCore Icecube can measure 10GeV – 10 11 GeV neutrinos ! DeepCore atmospheric muon event IceCube neutrino event O(0.1-1)TeV muon O(10-100)TeV muon DeepCore
Upward going muon* neutrino sample (8 years/2009-2016) *Select muon induced by muon neutrino CC interactions 〜 880TeV upward through- going muon track event Phys. Rev. Lett. 115, 081102 (2015) High energy starting event** neutrino sample (7.5 years/2010-2017) **Select neutrino events with outer layer detector as muon veto Cascade + E dep ~1PeV 15 PRL 111 (2013) 021103 PRL 113, 101101 (2014)
Best single power-law fit results • Good agreements of independent astrophysical neutrino samples above 200TeV • Detailed consistency studies on <200TeV still on going 16
1-2 PeV cascade events 6.0 ± 0.3 PeV cascade event - well compatible with Glashow resonance! ⇒ Existence of anti-electron neutrino Simulated GR event Highest energy event to date, an upward-going track. • Deposited energy 2.6 ± 0.3 PeV • Median neutrino energy 8.7 PeV 17 • Observed photoelectrons 130,000 pe
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>200 TeV 19
Neutrino Online Alert System IceCube: Before 2016 April, private on-site event analysis and alert Iridium satellites alert system existed. BUT system has been in operation background dominant n April il 2016: Acti ctivated public lic high energy n Flare and on onlin line ch channel l with ith sign ignal exposure in the effi ficie iency of of >3 >30-50 50% Alert! universe (E (EHE and HE HESE ch channels) Latency time: a few tens of seconds “The IceCube rea ealti time alert system”, Astropartic icle Physics, 92, , 30 – 41,( 2017) Telescopes over the world! (Good opportunities for telescopes of all sizes everywhere) 20
Science 361 (2018) IceCube-170922A event • 2017/9/22 20:54:30.43 UTC • 5th and the most cosmic neutrino signal like EHE alert • automated alert was distributed to observers just 43 seconds later Fermi Telescope gamma-rays neutrinos neutrino observed Optical telescopes optical light Kanata telescope ...and many more telescope Magic telescope 21
HE gamma-ray observations 23.7 ± 2.8 TeV muon energy loss in the detector a most probable neutrino energy of 290 TeV VHE gamma-ray observations • Furthermore TXS 0506+056 was observed VHE gamma-ray Magic telescope (E > 100GeV) Neutrino energy PDF with >6.2σ (ATel#10817) 22
9 years 2017 April Fermi-LAT: >1GeV light curve 4-week bin (9.2 years) 6 times brighter than the baseline IceCube 170922A 23
n -ray radio optical x-ray TXS 0506+056 BL Lac Gray: Archival 24
𝑦 2 𝑦 𝑈𝑌𝑇 − Ԧ 1 ൘ − (2𝜏 2 ) 𝑄 𝑡𝑞𝑏𝑢𝑗𝑏𝑚 = 2𝜌𝜏 2 𝑓 𝑜 𝑡 𝑜 𝑐 𝑄 𝑇 𝑂 • 𝑀 = ς 𝑗 𝑂 𝑄 𝑇 + 𝑂 𝑄 𝐶 → 𝑈𝑇(𝑂 = 1) ∝ log 𝑄 𝐶 ① flux variability 𝐽 𝛿 𝑢 𝑋 𝑢𝑓𝑛𝑞𝑝𝑠𝑏𝑚 ∝ < 𝐽 𝛿 𝑢 > ② energy flux 2D Gaussian from n ang resol. 𝜄 -dependent acceptance from light curve 100𝐻𝑓𝑊 𝑒𝐽 𝛿 𝑢 𝑋 𝑢𝑓𝑛𝑞𝑝𝑠𝑏𝑚 ∝ න 𝐹 𝛿 𝑒𝐹 𝛿 𝑒𝐹 𝛿 1𝐻𝑓𝑊 3000 fermi light curves from M. Hayashida no correlation vs correlation → 4.1𝜏 → Corrections for all 10 alerts issued → ≈3σ Both cases: previously and the 41 archival events 25
𝑜 𝑡 𝑜 𝑐 𝑂 • 𝑀 = ς 𝑗 𝑂 𝑄 𝑇 + 𝑂 𝑄 𝐶 𝜄 -dependent acceptance 2D Gaussian from n ang resol. square and Gaussian x power-law signal flux parameters: 𝑦 2 𝑦 𝑈𝑌𝑇 − Ԧ 1 ൘ − (2𝜏 2 ) center time and time window 𝑄 𝑡𝑞𝑏𝑢𝑗𝑏𝑚 = 2𝜌𝜏 2 𝑓 parameters: spectral index and normalization 2014/15 neutrino flare 26
supernova active galactic nuclei (blazar) Sun Earth However, Fermi blazer contribution to IceCube diffuse flux is <10% • What’s the other sources? • What make TXS050-056 special? typical neutrino typical geo-neutrino typical neutrino likely neutrino energy energy energy energy >100,000,000MeV <20MeV <4MeV <100MeV Natural to have Distance to the object observational bias Distance to the object 4,000,000,000 light Distance to the object Distance to the object to find from brighter 0.00001581 light years 0 light years 160,000 light years years (149,600,000km) objects Distance from the Earth to Galactic center 28,000 light years 27
• Surface array muon veto CR physics • Radio array cosmogenic neutrino neutrino >10 PeV IceCube 28
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m default factor taken into account m slightly downgoing horizontal direction is important for >100TeV neutrinos 30
• Detector effective muon area － x 4 ～ 5 (horizontal) default factor gives a factor of 5 better sensitivity • angular resolution － x ～ 0.45 ( horizontal ) • Further signal/bg improvements with new optical sensors ( cascade and muon reconstruction quality and BG reduction, detector/ice systematics ) give even better sensitivity 31
Cascade channel is complementary to upward muon m track channel ν l l , t • Good energy resolution of ~10% ν l W, e • Directional resolution is ~10 ° (ice systematic Z hadronic dominant) shower • Less atmospheric neutrino background • lower energy threshold (10TeV – 100TeV) • Sensitive to full sky 32
zenith/azimuth error Case with minimal imal ice systemat matics ics ~10 ° ~3 ° Current • Chiba IceCube group: Designed new OM “DEgg” with improved sensitivity (x 2 from IceCube optical sensor) • Responsible for production/calibration of 300 DEgg to be Shipped to South Pole by Sept 2021 (the other 400 oms are from US and Germany) 33 30cm
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