A COMBINED MAXIMUM-LIKELIHOOD ANALYSIS OF THE HIGH-ENERGY ASTROPHYSICAL NEUTRINO FLUX MEASURED WITH ICECUBE

被引:398
作者
Aartsen, M. G. [1 ]
Abraham, K. [2 ]
Ackermann, M. [3 ]
Adams, J. [4 ]
Aguilar, J. A. [5 ]
Ahlers, M. [6 ,7 ]
Ahrens, M. [8 ,9 ]
Altmann, D. [10 ]
Anderson, T. [11 ]
Archinger, M. [12 ]
Arguelles, C. [6 ,7 ]
Arlen, T. C. [11 ]
Auffenberg, J. [13 ]
Bai, X. [14 ]
Barwick, S. W. [15 ]
Baum, V. [12 ]
Bay, R. [16 ]
Beatty, J. J. [17 ,18 ,19 ]
Tjus, J. Becker [20 ]
Becker, K. -H. [21 ]
Beiser, E. [6 ,7 ]
BenZvi, S. [6 ,7 ]
Berghaus, P. [3 ]
Berley, D. [22 ]
Bernardini, E. [3 ]
Bernhard, A. [2 ]
Besson, D. Z. [23 ]
Binder, G. [16 ,24 ]
Bindig, D. [21 ]
Bissok, M. [13 ]
Blaufuss, E. [22 ]
Blumenthal, J. [13 ]
Boersma, D. J. [25 ]
Bohm, C. [8 ,9 ]
Boerner, M. [26 ]
Bos, F. [20 ]
Bose, D. [27 ]
Boeser, S. [12 ]
Botner, O. [25 ]
Braun, J. [6 ,7 ]
Brayeur, L. [28 ]
Bretz, H. -P. [3 ]
Brown, A. M. [4 ]
Buzinsky, N. [29 ]
Casey, J. [30 ,31 ]
Casier, M. [28 ]
Cheung, E. [22 ]
Chirkin, D. [6 ,7 ]
Christov, A. [32 ]
Christy, B. [22 ]
机构
[1] Univ Adelaide, Dept Phys, Adelaide, SA 5005, Australia
[2] Tech Univ Munich, D-85748 Garching, Germany
[3] DESY, D-15735 Zeuthen, Germany
[4] Univ Canterbury, Dept Phys & Astron, Christchurch 1, New Zealand
[5] Univ Libre Bruxelles, Sci Fac CP230, B-1050 Brussels, Belgium
[6] Univ Wisconsin, Dept Phys, Madison, WI 53706 USA
[7] Univ Wisconsin, Wisconsin IceCube Particle Astrophys Ctr, Madison, WI 53706 USA
[8] Stockholm Univ, Oskar Klein Ctr, SE-10691 Stockholm, Sweden
[9] Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden
[10] Univ Erlangen Nurnberg, Erlangen Ctr Astroparticle Phys, D-91058 Erlangen, Germany
[11] Penn State Univ, Dept Phys, University Pk, PA 16802 USA
[12] Johannes Gutenberg Univ Mainz, Inst Phys, D-55099 Mainz, Germany
[13] Rhein Westfal TH Aachen, Inst Phys 3, D-52056 Aachen, Germany
[14] South Dakota Sch Mines & Technol, Dept Phys, Rapid City, SD 57701 USA
[15] Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA
[16] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA
[17] Ohio State Univ, Dept Phys, Columbus, OH 43210 USA
[18] Ohio State Univ, Ctr Cosmol & Astroparticle Phys, Columbus, OH 43210 USA
[19] Ohio State Univ, Dept Astron, Columbus, OH 43210 USA
[20] Ruhr Univ Bochum, Fak Phys & Astron, D-44780 Bochum, Germany
[21] Berg Univ Wuppertal, Dept Phys, D-42119 Wuppertal, Germany
[22] Univ Maryland, Dept Phys, College Pk, MD 20742 USA
[23] Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA
[24] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA
[25] Uppsala Univ, Dept Phys & Astron, SE-75120 Uppsala, Sweden
[26] TU Dortmund Univ, Dept Phys, D-44221 Dortmund, Germany
[27] Sungkyunkwan Univ, Dept Phys, Suwon 440746, South Korea
[28] Vrije Univ Brussel, Dienst ELEM, B-1050 Brussels, Belgium
[29] Univ Alberta, Dept Phys, Edmonton, AB T6G 2E1, Canada
[30] Georgia Inst Technol, Sch Phys, Atlanta, GA 30332 USA
[31] Georgia Inst Technol, Ctr Relativist Astrophys, Atlanta, GA 30332 USA
[32] Univ Geneva, Dept Phys Nucl & Corpusculaire, CH-1211 Geneva, Switzerland
[33] Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, Canada
[34] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[35] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA
[36] Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA
[37] Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA
[38] Univ Ghent, Dept Phys & Astron, B-9000 Ghent, Belgium
[39] Humboldt Univ, Inst Phys, D-12489 Berlin, Germany
[40] Southern Univ, Dept Phys, Baton Rouge, LA 70813 USA
[41] Chiba Univ, Dept Phys, Chiba 2638522, Japan
[42] Univ Wisconsin, Dept Astron, Madison, WI 53706 USA
[43] Univ Bonn, Inst Phys, D-53115 Bonn, Germany
[44] Clark Atlanta Univ, CTSPS, Atlanta, GA 30314 USA
[45] Yale Univ, Dept Phys, New Haven, CT 06520 USA
[46] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA
[47] Univ Mons, B-7000 Mons, Belgium
[48] Univ Copenhagen, Niels Bohr Inst, DK-2100 Copenhagen, Denmark
[49] Drexel Univ, Dept Phys, Philadelphia, PA 19104 USA
[50] Univ Wisconsin, Dept Phys, River Falls, WI 54022 USA
基金
美国国家科学基金会; 加拿大自然科学与工程研究理事会; 澳大利亚研究理事会; 新加坡国家研究基金会; 瑞士国家科学基金会; 瑞典研究理事会;
关键词
astroparticle physics; methods: data analysis; neutrinos; GAMMA-RAY SOURCES; COSMIC-RAYS; POINT-LIKE; PERFORMANCE; TELESCOPE; EMISSION; GALAXIES; SPECTRUM; SEARCHES; SIGNALS;
D O I
10.1088/0004-637X/809/1/98
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for neutrino events with deposited energies greater than or similar to 30 TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, nu(mu)-induced tracks from the Northern Hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle, and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index -2.50 +/- 0.09 and a flux at 100 TeV of (6.7(-1.2)(+1.1)) x 10(-18) GeV-1 s(-1) sr(-1) cm(-2). Under the same assumptions, an unbroken power law with index -2 is disfavored with a significance of 3.8 sigma (p = 0.0066%) with respect to the best fit. This significance is reduced to 2.1 sigma (p = 1.7%) if instead we compare the best fit to a spectrum with index -2 that has an exponential cut-off at high energies. Allowing the electron-neutrino flux to deviate from the other two flavors, we find a nu(e) fraction of 0.18 +/- 0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay-dominated sources, is rejected with a significance of 3.6 sigma ( p = 0.014%).
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页数:15
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[1]   Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube [J].
Aartsen, M. G. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Ahrens, M. ;
Altmann, D. ;
Anderson, T. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bos, F. ;
Boeser, D. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Buzinsky, N. ;
Casey, J. ;
Casier, M. ;
Cheung, E. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz .
PHYSICAL REVIEW LETTERS, 2015, 114 (17)
[2]   Atmospheric and astrophysical neutrinos above 1 TeV interacting in IceCube [J].
Aartsen, M. G. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Ahrens, M. ;
Altmann, D. ;
Anderson, T. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bos, F. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Buzinsky, N. ;
Casey, J. ;
Casier, M. ;
Cheung, E. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cowen, D. F. .
PHYSICAL REVIEW D, 2015, 91 (02)
[3]   SEARCHES FOR EXTENDED AND POINT-LIKE NEUTRINO SOURCES WITH FOUR YEARS OF ICECUBE DATA [J].
Aartsen, M. G. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Ahrens, M. ;
Altmann, D. ;
Anderson, T. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Barwick, S. W. ;
Baum, V. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bos, F. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Casey, J. ;
Casier, M. ;
Cheung, E. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz ;
Danninger, M. .
ASTROPHYSICAL JOURNAL, 2014, 796 (02)
[4]   Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data [J].
Aartsen, M. G. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Ahrens, M. ;
Altmann, D. ;
Anderson, T. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Barwick, S. W. ;
Baum, V. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz ;
Danninger, M. ;
Daughhetee, J. ;
Davis, J. C. .
PHYSICAL REVIEW LETTERS, 2014, 113 (10)
[5]   Observation of the cosmic-ray shadow of the Moon with IceCube [J].
Aartsen, M. G. ;
Abbasi, R. ;
Abdou, Y. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Altmann, D. ;
Auffenberg, J. ;
Bai, X. ;
Baker, M. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Bechet, S. ;
Tjus, J. Becker ;
Becker, K. -H. ;
Bell, M. ;
Benabderrahmane, M. L. ;
BenZvi, S. ;
Berdermann, J. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Bertrand, D. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohaichuk, S. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Bruijn, R. ;
Brunner, J. ;
Carson, M. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. .
PHYSICAL REVIEW D, 2014, 89 (10)
[6]   Search for neutrino-induced particle showers with IceCube-40 [J].
Aartsen, M. G. ;
Abbasi, R. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Altmann, D. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Baker, M. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Bruijn, R. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cohen, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz .
PHYSICAL REVIEW D, 2014, 89 (10)
[7]   Search for a diffuse flux of astrophysical muon neutrinos with the IceCube 59-string configuration [J].
Aartsen, M. G. ;
Abbasi, R. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Altmann, D. ;
Arguelles, C. ;
Arlen, T. C. ;
Auffenberg, J. ;
Bai, X. ;
Baker, M. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K. -H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H. -P. ;
Brown, A. M. ;
Bruijn, R. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cohen, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz .
PHYSICAL REVIEW D, 2014, 89 (06)
[8]   Energy reconstruction methods in the IceCube neutrino telescope [J].
Aartsen, M. G. ;
Abbasi, R. ;
Ackermann, M. ;
Adams, J. ;
Aguilar, J. A. ;
Ahlers, M. ;
Altmann, D. ;
Arguelles, C. ;
Auffenberg, J. ;
Bai, X. ;
Baker, M. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Tjus, J. Becker ;
Becker, K-H. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H-P. ;
Brown, A. M. ;
Bruijn, R. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Classen, L. ;
Clevermann, F. ;
Coenders, S. ;
Cohen, S. ;
Cowen, D. F. ;
Silva, A. H. Cruz ;
Danninger, M. .
JOURNAL OF INSTRUMENTATION, 2014, 9
[9]   Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector [J].
Aartsen, M. G. ;
Abbasi, R. ;
Abdou, Y. ;
Ackermann, M. ;
Adams, J. ;
Aguitar, J. A. ;
Alders, M. ;
Altmann, D. ;
Auffenberg, J. ;
Ba, X. ;
Baker, M. ;
Barwick, S. W. ;
Baum, V. ;
Bay, R. ;
Beatty, J. J. ;
Bechet, S. ;
Tjus, J. Becker ;
Becker, K-H. ;
Benabderrahmane, M. L. ;
BenZvi, S. ;
Berghaus, P. ;
Berley, D. ;
Bernardini, E. ;
Bernhard, A. ;
Bertrand, D. ;
Besson, D. Z. ;
Binder, G. ;
Bindig, D. ;
Bissok, M. ;
Blaufuss, E. ;
Blumenthal, J. ;
Boersma, D. J. ;
Boliaichuk, S. ;
Bohm, C. ;
Bose, D. ;
Boeser, S. ;
Botner, O. ;
Brayeur, L. ;
Bretz, H-P. ;
Brown, A. M. ;
Bruijn, R. ;
Brunner, J. ;
Carson, M. ;
Casey, J. ;
Casier, M. ;
Chirkin, D. ;
Christov, A. ;
Christy, B. ;
Clark, K. ;
Cleverrnann, F. .
SCIENCE, 2013, 342 (6161) :947-+
[10]  
Aartsen M. G., 2015, PHRVL IN PRESS