All-flavor Neutrino Point-like Source Search with the ANTARES - PowerPoint PPT Presentation

All-flavor Neutrino Point-like Source Search with the ANTARES Neutrino Telescope Giulia Illuminati on behalf of the ANTARES Collaboration ICRC2017- 14/07/2017 – Bexco, Busan, Korea

The ANTARES neutrino telescope: Detector layout o Largest neutrino telescope in the Northern Hemisphere o First detection line installed in early 2006 o Completed in 2008 o 2475 m depth in the Mediterranean Sea o 40 km offshore from T oulon Buoy 450 m • Three-dimensional array of 885 PMTs Electro-optical cable • 12 vertical lines, 25 storeys • 3 PMTs per storey Junction • PMT facing 45° downwards boxes ~60 m 2

The ANTARES neutrino telescope: Detection principle Earth used as shield for atmospheric muons • Either CC or NC interaction with a nucleus • inside or nearby the detector volume Cherenkov radiation detected by the PMTs • Position, time and charge used to reconstruct • direction and energy Track-like events: Shower-like events: ν μ ( ν τ ) neutrino all neutrinos NC ν e , ν τ CC interaction inside CC interaction near the detector è track or very close to the detector è shower New shower reconstruction mechanism recently released [1] • Shower-like events included for the first time in a point-like source search with ANTARES • 3 [1] PoS ICRC2015 (2016) 1078

All-flavour neutrino point source analysis: Data sample o Jan 29, 2007 to Dec 31, 2015 Total number of selected events: Ø 7629 tracks o 2423.6 days of lifetime o Track and Shower events Ø 180 showers 1 4 s) Cumulative probability 2 0.9 cm 3.5 PRELIMINARY Tracks 0.8 -1 GeV 3 0.7 Showers x 3 2.5 8 0.6 /(10 0.5 2 S A 0.4 Track events 1.5 Shower events 0.3 1 0.2 PRELIMINARY 0.5 0.1 0 0 2 1 2 1 0.8 0.6 0.4 0.2 0 0.2 0.4 0.6 0.8 1 − − − − − − − 10 10 1 10 10 ∆ Ψ [ ° ] sin δ Probability to obtain a reconstructed angle within ΔΨ Acceptance as a function of the source declination for an E -2 energy spectrum. between the reconstructed direction with respect to the true Monte Carlo neutrino direction. A neutrino flux 4 with an energy spectrum E -2 is assumed.

Search method: likelihood . / , . + 1 . 2 , . − + %,- log$ %&' = * * log + %,- . ,∈. Shower signal PDFs Track signal PDFs %F = / %789: ; , ⋅ / :?:6-@ (B , ) 56 = / %789: ; , ,= , ⋅ / :?:6-@ (B , ,= , |D , ) / , / , Track background PDFs Shower background PDFs 56 = 2 %789: D , ⋅ 2 :?:6-@ (B , ,= , |D , ) %F = 2 %789: D , ⋅ 2 :?:6-@ (B , ) 2 , 2 , T est Statistic G = log$ %&' − log$ ' 5

Search method: likelihood . / , . + 1 . 2 , . − + %,- log$ %&' = * * log + %,- . ,∈. Selected track events 800 δ Signal PDFs 700 600 500 = / %789: ⋅ / :?:6-@ 400 / , 300 200 PRELIMINARY 100 RA 0 − 1 − 0.8 − 0.6 − 0.4 − 0.2 0 0.2 0.4 0.6 0.8 1 sin( ) δ tr Background PDFs Background Signal = 2 %789: ⋅ 2 :?:6-@ 2 , E 6

Search method: strategies Full-sky search Galactic Centre region search o o • TS evaluated in squares of 1°x1° over the ANTARES visible sky • TS evaluated in squares of 1°x1° over a restricted region around the GC: ellipse, 15° semi-axis in galactic latitude, 20° semi-axis in galactic longitude Candidate list searches Sagittarius A* location o o • 106 known astrophysical objects (Pulsars, SNRs, …) • T ested as an extended source by assuming a Gaussian emission profile of various widths • 13 IceCube tracks from the HESE sample [1][2] Free parameters: Ø + 56 Ø + %F Ø ; %HI69: Ø D %HI69: 7 PRELIMINARY [1] arXiv:1405.5303 [2] PoS ICRC2015 (2016) 1081

Results: Most significant cluster Full-sky search PRELIMINARY Most significant cluster located at ( α , δ ) = (343.8°, 23.5°) Post-trial significance: 5.9% or 1.9 σ (two-sided convention) Upper limit on the neutrino flux: E 2 d ɸ /dE = 3.8 x 10 -8 GeV cm -2 s -1 8

Results: Most significant cluster Candidate list search – 106 candidates PRELIMINARY Most significant cluster located at HESSJ0632+057 location ( α , δ ) = (98.24°, 5.81°) Post-trial significance: 13% or 1.5 σ (two-sided convention) Upper limit on the neutrino flux: E 2 d ɸ /dE = 2.4 x 10 -8 GeV cm -2 s -1 9

Results: Most significant cluster Candidate list search – 13 HESE PRELIMINARY Most significant cluster located at ( α , δ ) = (130.1°, -29.8°) at a distance of 1.5° from the HESE track with ID 3 Post-trial significance: 20% or 1.3 σ (two-sided convention) Upper limit on the neutrino flux: E 2 d ɸ /dE = 2.1 x 10 -8 GeV cm -2 s -1 10

Results: Most significant cluster Galactic Centre region search PRELIMINARY Other spectral indices ( ɣ = 2.1, 2.3, 2.5) and source extensions ( σ = 0.5°, 1.0°, 2.0°) tested Most significant clusters located at Ø ( α , δ ) = (257.4°, -41.0°) for a E -2 spectrum and point-like source Post-trial significance: 60% or 0.5 σ (two-sided convention) Ø ( α , δ ) = (273.0°, -42.2°) for a E -2.5 spectrum and point-like source Post-trial significance: 11 30% or 1.0 σ (two-sided convention)

Results: Most significant cluster Sagittarius A* PRELIMINARY Location: ( α , δ ) = (266.42°, -29.01°) Investigated as a point-like source ( σ = 0°) and as an extended source ( σ = 0.5°, 1.0°, 2.0°) Largest excess above background found for Ø Point-like assumption Ø Pre-trial significance: 22% or 1.2 σ (two-sided convention) 12

Results: Sensitivities and Limits Full-sky and Candidate list searches 5 − 10 ] ANTARES 2007-15 sensitivity -1 s ANTARES 2007-15 sensitivity (E < 100 TeV) ν -2 ANTARES 2007-15 limits (candidate list) [GeV cm ANTARES 2007-15 limits (candidate list for HESE events) ANTARES 2007-15 limits (1 declination bands) ° − 6 10 IceCube 7 years sensitivity [ApJ 835(2017)2 151] IceCube 3 years MESE sensitivity (E < 100 TeV) [ApJ 824(2016)2 L28] ν IceCube 7 years limits [ApJ 835(2017)2 151] 90%CL 7 − 10 Φ 2 E 8 − 10 − 9 10 PRELIMINARY 10 − 10 1 0.8 0.6 0.4 0.2 0 0.2 0.4 0.6 0.8 1 − − − − − sin δ Sensitivities and upper limits at a 90% C.L. on the signal flux 13 from the Full-sky and the Candidate list searches

Results: Sensitivities and Limits Galactic Centre region search ] -1 12 − 10 × s 30 ] -1 -2 s cm -2 28 10 − [TeV cm 10 -1 γ [TeV 26 = 2.5 γ 24 90%CL 90%CL = 2.3 γ = 2.0 σ ° γ = 2.1 σ = 1.0 ° 0 22 Φ = 2.0 Φ γ σ = 0.5 ° σ = 0.0 ° 2 γ E E 20 18 PRELIMINARY PRELIMINARY 16 − 11 10 0.7 0.6 0.5 0.4 0.3 0.2 − − − − − − 0.7 0.6 0.5 0.4 0.3 0.2 − − − − − − sin δ sin δ 90% C.L. upper limits of the search restricted to the region around the origin of the galactic coordinates at ( α , δ ) = (266.40°,-28.94°) assuming different spectral indices for the neutrino flux (left) and different source extensions for ɣ = 2 (right). 14

Results: Sensitivities and Limits Sagittarius A* ] -1 s -2 10 − [TeV cm 10 90%CL Φ 2 E 11 − 10 PRELIMINARY Sensitivity (assuming width) Sensitivity (assuming point-source) 90% C.L. Limit 5 discovery flux (assuming width) σ 5 discovery flux (assuming point-source) σ 0 1 2 3 4 5 6 [ ] σ ° Discovery flux (solid red), median sensitivity (dotted blue) and upper limits (solid blue) at A* at ( α , δ ) = (266.42°,-29.01°) 90% C.L. for a search for an extended source at Sagittarius assuming different angular extensions σ . The dashed lines correspond to the point-like 15 source assumption.

Conclusions Ø First all-flavor neutrino point-like source search with the ANTARES neutrino telescope Ø No significant evidence of cosmic neutrino sources found Ø Full-sky search: largest excess found at ( α , δ ) = (343.8°, 23.5°) with 1.9 σ significance Ø Candidate list search over 106 candidates: largest excess found for HESSJ0632+057 with 1.5 σ significance Ø Candidate list search over 13 IceCube HESE: largest excess found HESE with ID 3 with 1.3 σ significance Ø Galactic Centre region search: largest excess found at ( α , δ ) = (257.4°, -41.0°) for a E -2 spectrum and point-like source with 0.5 σ significance Ø Sagittarius A*: largest excess found for a point-like source with 1.2 σ significance Ø Most sensitive limits for a large fraction of the Southern Sky set, especially at neutrino energies below 100 T eV. 16

Backup 17

Candidate list arXiv:1706.01857 18

IceCube HESE candidates arXiv:1706.01857 19

Selection criteria arXiv:1706.01857 20

Selection criteria Track-like events selection cuts Shower-like events selection cuts Quality parameter: Λ tr > -5.2 § T rack veto: not selected as track § Estimated angular error: β tr < 1° Estimated angular error: β sh < 1° § § Up-going: cos θ tr > -0.1 Up-going: cos θ sh > -0.1 § § Energy estimator: log 10 ( J ) > 1.6 Interaction vertex: R sh < 300 m, |Z sh | < 250 m § § Muon track length: L μ > 360 m M-estimator: Mest < 1000 § § Random Decision Forest: RDF > 0.3 § Muon likelihood: K μ > 50 § 21