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Aartsen, M. G.,Abraham, K.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Arguelles, C.,Arlen, T. C.,Auffenberg, J Springer-Verlag 2016 European Physical Journal C Vol.76 No.10
<P>We present the first IceCube search for a signal of dark matter annihilations in the Milky Way using all-flavour neutrino-induced particle cascades. The analysis focuses on the DeepCore sub-detector of IceCube, and uses the surrounding IceCube strings as a veto region in order to select starting events in the DeepCore volume. We use 329 live-days of data from IceCube operating in its 86-string configuration during 2011-2012. No neutrino excess is found, the final result being compatible with the background-only hypothesis. From this null result, we derive upper limits on the velocity-averaged self-annihilation cross-section, , for dark matter candidate masses ranging from 30 GeV up to 10 TeV, assuming both a cuspy and a flat-cored dark matter halo profile. For dark matter masses between 200 GeV and 10 TeV, the results improve on all previous IceCube results on , reaching a level of 10 cm s, depending on the annihilation channel assumed, for a cusped NFW profile. The analysis demonstrates that all-flavour searches are competitive with muon channel searches despite the intrinsically worse angular resolution of cascades compared to muon tracks in IceCube.</P>
Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A
Aartsen, Mark,Ackermann, Markus,Adams, Jenni,Aguilar, Juan Antonio,Ahlers, Markus,Ahrens, Maryon,Al Samarai, Imen,Altmann, David,Andeen, Karen,Anderson, Tyler,Ansseau, Isabelle,Anton, Gisela,Argü American Association for the Advancement of Scienc 2018 Science Vol.361 No.6398
<P>Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera-electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray-emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.</P>
Search for annihilating dark matter in the Sun with 3 years of IceCube data : IceCube Collaboration
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Bai, X. Springer-Verlag 2017 The European physical journal. C, Particles and fi Vol.77 No.3
Search for sterile neutrino mixing using three years of IceCube DeepCore data
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Al Samarai, I.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Argü,elles, C.,Auffenberg, J.,Axa American Physical Society 2017 Physical review. D Vol.95 No.11
<P>We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10-60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (Delta m(41)(2) similar to 1 eV(2)) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of vertical bar U mu(4)vertical bar(2) < 0.11 and vertical bar U-tau 4 vertical bar(2) < 0.15 (90% C. L.) for the sterile neutrino mass splitting Delta m(41)(2) = 1.0 eV(2).</P>
SEARCH FOR SOURCES OF HIGH-ENERGY NEUTRONS WITH FOUR YEARS OF DATA FROM THE ICETOP DETECTOR
Aartsen, M. G.,Abraham, K.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Argü,elles, C.,Auffenberg, J.,Axani, American Astronomical Society 2016 The Astrophysical journal Vol.830 No.2
<P>IceTop is an air-shower array located on the Antarctic ice sheet at the geographic South Pole. IceTop can detect an astrophysical flux of neutrons from Galactic sources as an excess of cosmic-ray air showers arriving from the source direction. Neutrons are undeflected by the Galactic magnetic field and can typically travel 10 (E/PeV) pc before decay. Two searches are performed using 4 yr of the IceTop data set to look for a statistically significant excess of events with energies above 10 PeV (10(16) eV) arriving within a small solid angle. The all-sky search method covers from -90 degrees to approximately -50 degrees in declination. No significant excess is found. A targeted search is also performed, looking for significant correlation with candidate sources in different target sets. This search uses a higher-energy cut (100 PeV) since most target objects lie beyond 1 kpc. The target sets include pulsars with confirmed TeV energy photon fluxes and high-mass X-ray binaries. No significant correlation is found for any target set. Flux upper limits are determined for both searches, which can constrain Galactic neutron sources and production scenarios.</P>
Measurement of atmospheric tau neutrino appearance with IceCube DeepCore
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Backes, P.,Bagherpour, American Physical Society 2019 Physical review. D Vol.99 No.3
Aartsen, M. G.,Abraham, K.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Argü,elles, C.,Auffenberg, J.,Axani, Springer-Verlag 2017 European Physical Journal C Vol.77 No.2
<P>We present the results of the first IceCube search for dark matter annihilation in the center of the Earth. Weakly interacting massive particles (WIMPs), candidates for dark matter, can scatter off nuclei inside the Earth and fall below its escape velocity. Over time the captured WIMPs will be accumulated and may eventually self-annihilate. Among the annihilation products only neutrinos can escape from the center of the Earth. Large-scale neutrino telescopes, such as the cubic kilometer IceCube Neutrino Observatory located at the South Pole, can be used to search for such neutrino fluxes. Data from 327 days of detector livetime during 2011/2012 were analyzed. No excess beyond the expected background from atmospheric neutrinos was detected. The derived upper limits on the annihilation rate of WIMPs in the Earth (Gamma(A) = 1.12 x 10(14) s(-1) for WIMP masses of 50 GeV annihilating into tau leptons) and the resulting muon flux are an order of magnitude stronger than the limits of the last analysis performed with data from IceCube's predecessor AMANDA. The limits can be translated in terms of a spin-independent WIMP-nucleon cross section. For a WIMP mass of 50GeV this analysis results in the most restrictive limits achieved with IceCube data.</P>
Astrophysical neutrinos and cosmic rays observed by IceCube
Aartsen, M.G.,Ackermann, M.,Adams, J.,Aguilar, J.A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Bai, X.,Ba Elsevier 2018 ADVANCES IN SPACE RESEARCH Vol.62 No.10
<P><B>Abstract</B></P> <P>The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of recent findings from the analysis of IceCube data, and their implications to our understanding of cosmic rays.</P>
THE CONTRIBUTION OF<i>FERMI</i>-2LAC BLAZARS TO DIFFUSE TEV-PEV NEUTRINO FLUX
Aartsen, M. G.,Abraham, K.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Archinger, M.,Arguelles, C.,Arlen, T. C.,Auffenberg, J American Astronomical Society 2017 The Astrophysical journal Vol.835 No.1
<P>The recent discovery of a diffuse cosmic neutrino flux extending up to PeV energies raises the question of which astrophysical sources generate this signal. Blazars are one class of extragalactic sources which may produce such high-energy neutrinos. We present a likelihood analysis searching for cumulative neutrino emission from blazars in the 2nd Fermi-LAT AGN catalog (2LAC) using IceCube neutrino data set 2009-12, which was optimized for the detection of individual sources. In contrast to those in previous searches with IceCube, the populations investigated contain up to hundreds of sources, the largest one being the entire blazar sample in the 2LAC catalog. No significant excess is observed, and upper limits for the cumulative flux from these populations are obtained. These constrain the maximum contribution of 2LAC blazars to the observed astrophysical neutrino flux to 27% or less between around 10 TeV and 2 PeV, assuming the equipartition of flavors on Earth and a single power-law spectrum with a spectral index of -2.5. We can still exclude the fact that 2LAC blazars (and their subpopulations) emit more than 50% of the observed neutrinos up to a spectral index as hard as -2.2 in the same energy range. Our result takes into account the fact that the neutrino source count distribution is unknown, and it does not assume strict proportionality of the neutrino flux to the measured 2LAC gamma-ray signal for each source. Additionally, we constrain recent models for neutrino emission by blazars.</P>