Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

M G Aartsen ,L Rauch,J Bourbeau,F Tenholt,T Deyoung,M De With,K Jero,D Seckel,J Hignight,A Waza,P Peiffer,N Wandkowsky,J Stachurska,M Medici,N Van Eijndhoven,C Rott,K Mase,G Merino,A Fritz,A Stößl,D Berley,R Cross,P Schlunder,K Helbing,G Neer,M Sutherland,K Filimonov,N Kurahashi,B Eberhardt,T Montaruli,Z Griffith,I Ansseau,S Flis,T Schmidt,M Börner,J Wood,G Krückl,I Taboada,T Karg,K Andeen,J Auffenberg,S Kopper,D Soldin,E Pinat,E Cheung,L Wills,A Kappes,S Tilav,S Toscano,T Stanev,K Rawlins,K Wiebe,S Sarkar,A Wallace,M Plum,R Maunu,M Dunkman,T Palczewski,D Pieloth,P Desiati,H Niederhausen,L Rädel,S De Ridder,S Fahey,J Sandroos,F Bos,H Kolanoski,E Resconi,M Song,S Schoenen,A Schneider,E Woolsey,J Kiryluk,M Usner,A Ishihara,P Eller,M Kauer,A Burgman,C Kopper,A Hallgren,F Halzen,D Chirkin,D Van Eijk,S Hickford,R Maruyama,A Keivani,J Madsen,F Huang,M Kowalski,T Glüsenkamp,K Hoshina,S Sclafani,H.-P Bretz,T Stezelberger,R Hellauer,D Hebecker,C Spiering,M Kroll,A Kyriacou,M Wolf,E Jacobi,E Friedman,T Kittler,K Satalecka,R Reimann,A O’Murchadha,H Bagherpour,L Köpke,J Gallagher,A Karle,G Yodh,S In,B Relethford,I Al Samarai,M Tselengidou,L Gerhardt,W Giang,A Turcati,R Hoffmann,A Pizzuto,U Katz,K Clark,T Meures,S Seunarine,M Brenzke,E Blaufuss,M Day,E Bernardini,K Hanson,T Kintscher,A Steuer,T Menne,A Goldschmidt,S Robertson,G Anton,N Whitehorn,M Ahlers,A Terliuk,X Bai,G De Wasseige,J Stettner,G Momenté,B Hokanson-Fasig,C Walck,A Christov,R Nahnhauer,M Rameez,G Maggi,L Wille,J Kim,L Classen,J Becker Tjus,W Rhode,A Sandrock,S Bron,O Botner,S Miarecki,T Carver,M Richman,K Meagher,A Olivas,C De Clercq,S Vanheule,R Koirala,A Obertacke Pollmann,D Heereman,L Halve,C Argüelles,A Franckowiak,J Felde,S Kunwar,K Ghorbani,D Grant,D Tosi,D Rysewyk,T Ruhe,M Ackermann,S Schöneberg,K Leonard,P Nakarmi,V Di Lorenzo,C Pérez De Los Heros,K Woschnagg,V Baum,M Vraeghe,N Iovine,G Binder,S Böser,D Ryckbosch,J Braun,T Stuttard,S Benzvi,M Stamatikos,E Unger,W Van Driessche,M Ahrens,D Bindig,M Labare,R Bay,B Eichmann,K Krings,K Hultqvist,M Leuermann,J Lünemann,M Wallraff,J Vandenbroucke,D Altmann,M Santander,C Finley,S Westerhoff,C Wendt,A Stasik,P A Toale ,T K Gaisser ,Kunal Deoskar ,M J Larson ,William Luszczak ,Jan Soedingrekso ,Gerrit Wrede ,Paul Coppin ,D J Koskinen ,Gabriel Collin ,D V Pankova ,D Besson ,G C Hill ,D F Cowen ,Lu Lu ,J H Adams ,Federica Bradascio ,B J Whelan ,Timothyblake Watson ,Juan Carlos Díaz–Vélez ,J P Koschinsky ,Jannes Brostean-Kaiser ,Christoph Tönnis ,J L Lanfranchi ,Merlin Schaufel ,Bunheng Ty ,Tobias Hoinka ,T R Wood ,Martin Rongen ,J L Kelley ,G T Przybylski ,Johannes Werthebach ,B J P Jones ,Yang Xu ,J A Aguilar ,Chunfai Tung ,C F Turley ,Summer Blot ,G S Japaridze ,Thomas Ehrhardt ,Anastasia Maria Barbano ,Yuya Makino ,X W Xu ,S E Sanchez Herrera ,Kendall Mahn ,Hrvoje Dujmović ,Mirco Hünnefeld ,D R Williams ,Shigeru Yoshida ,Paul Backes ,Elisa Lohfink ,F D Wandler ,Minjin Jeong ,Emily Dvorak ,D L Xu ,Ryo Nagai ,Giovanni Renzi ,J V Santen ,Hershal Pandya ,Pablo Correa ,R W Moore ,S W Barwick ,Christoph Raab ,Ibrahim Safa ,K D Hoffman ,S R Klein ,Theo Glauch ,P Kalaczyński ,S Ter–Antonyan ,P B Price ,Ch Weaver ,Cristian Jesús Lozano Mariscal ,J P Yañez ,Raffaela Busse ,Sarah Mancina ,Q R Liu ,J A Pepper ,Ali Kheirandish ,D R Nygren ,J G González ,Erin O’sullivan ,C H Wiebusch ,Lisa Johanna Schumacher ,Immacolata Carmen Rea ,Erik Ganster ,Tyler Anderson ,M N Tobin ,Ioana Codrina Maris ,Robert Stein ,J J Beatty ,C Böhm ,H.-P Dembinski ,Etienne Bourbeau ,J P Dumm ,Marjon Moulai ,Uwe Naumann ,Matthías Huber ,J M Conrad ,R G Stokstad ,Jessie Micallef ,G W Sullivan ,David Kappesser ,J P A M De André ,Karl‐Heinz Becker ,Woosik Kang ,S C Nowicki ,Raamis Hussain ,Maximilian Meier ,N L Strotjohann ,Frederik Hermann Lauber ,Spencer Axani ,James Delaunay ,Christian Haack ,A R Fazely ,P A Evenson ,Matthew J Weiss ,J P Barron ,G M Spiczak ,Pranav Dave ,Krijn De Vries ,Tianlu Yuan

doi:10.1103/physrevd.98.062003

Abstract

We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above $5\times 10^{6}$ GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above $10^{6}$ GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between $5 \times 10^{6}$ and $5 \times 10^{10}$ GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm GeV}/{\rm cm}^2\ \sec\ {\rm sr}$ at $10^9\ {\rm GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.

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