uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Hallgren, Allan
Alternative names
Publications (10 of 197) Show all publications
Aartsen, M. G., Abraham, K., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., . . . Zoll, M. (2017). All-sky Search for Time-integrated Neutrino Emission from Astrophysical Sources with 7 yr of IceCube Data. Astrophysical Journal, 835(2), Article ID 151.
Open this publication in new window or tab >>All-sky Search for Time-integrated Neutrino Emission from Astrophysical Sources with 7 yr of IceCube Data
Show others...
2017 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 835, no 2, 151Article in journal (Refereed) Published
Abstract [en]

Since the recent detection of an astrophysical flux of high-energy neutrinos, the question of its origin has not yet fully been answered. Much of what is known about this flux comes from a small event sample of high neutrino purity, good energy resolution, but large angular uncertainties. In searches for point-like sources, on the other hand, the best performance is given by using large statistics and good angular reconstructions. Track-like muon events produced in neutrino interactions satisfy these requirements. We present here the results of searches for point-like sources with neutrinos using data acquired by the IceCube detector over 7 yr from 2008 to 2015. The discovery potential of the analysis in the northern sky is now significantly below E(nu)(2)d phi/dE(nu) = 10(-12) TeV cm(-2) s(-1), on average 38% lower than the sensitivity of the previously published analysis of 4 yr exposure. No significant clustering of neutrinos above background expectation was observed, and implications for prominent neutrino source candidates are discussed.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keyword
astroparticle physics, galaxies: active, neutrinos
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-324355 (URN)10.3847/1538-4357/835/2/151 (DOI)000401145300012 ()
Funder
Swedish Research CouncilSwedish Polar Research SecretariatSwedish National Infrastructure for Computing (SNIC)Knut and Alice Wallenberg Foundation
Available from: 2017-06-16 Created: 2017-06-16 Last updated: 2017-06-16Bibliographically approved
Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., . . . Zoll, M. (2017). Extending the Search for Muon Neutrinos Coincident with Gamma-Ray Bursts in IceCube Data. Astrophysical Journal, 843(2), Article ID 112.
Open this publication in new window or tab >>Extending the Search for Muon Neutrinos Coincident with Gamma-Ray Bursts in IceCube Data
Show others...
2017 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 843, no 2, 112Article in journal (Refereed) Published
Abstract [en]

We present an all-sky search for muon neutrinos produced during the prompt γ-ray emission of 1172 gamma-ray bursts (GRBs) with the IceCube Neutrino Observatory. The detection of these neutrinos would constitute evidence for ultra-high-energy cosmic-ray (UHECR) production in GRBs, as interactions between accelerated protons and the prompt γ-ray field would yield charged pions, which decay to neutrinos. A previously reported search for muon neutrino tracks from northern hemisphere GRBs has been extended to include three additional years of IceCube data. A search for such tracks from southern hemisphere GRBs in five years of IceCube data has been introduced to enhance our sensitivity to the highest energy neutrinos. No significant correlation between neutrino events and observed GRBs is seen in the new data. Combining this result with previous muon neutrino track searches and a search for cascade signature events from all neutrino flavors, we obtain new constraints for single-zone fireball models of GRB neutrino and UHECR production.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keyword
acceleration of particles, astroparticle physics, gamma-ray burst: general, neutrinos
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-331240 (URN)10.3847/1538-4357/aa7569 (DOI)000405278700012 ()
Funder
Swedish Research CouncilSwedish Polar Research SecretariatSwedish National Infrastructure for Computing (SNIC)Knut and Alice Wallenberg Foundation
Available from: 2017-10-24 Created: 2017-10-24 Last updated: 2017-10-24Bibliographically approved
Aartsen, M. G., Abraham, K., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., . . . Zoll, M. (2017). First search for dark matter annihilations in the Earth with the IceCube detector. European Physical Journal C, 77(2), Article ID 82.
Open this publication in new window or tab >>First search for dark matter annihilations in the Earth with the IceCube detector
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, no 2, 82Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-322853 (URN)10.1140/epjc/s10052-016-4582-y (DOI)000400004800004 ()
Funder
Swedish Research CouncilSwedish Polar Research SecretariatSwedish National Infrastructure for Computing (SNIC)Knut and Alice Wallenberg FoundationGerman Research Foundation (DFG)Australian Research CouncilDanish National Research Foundation
Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2017-06-02Bibliographically approved
Aartsen, M. G., Abraham, K., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., . . . Zoll, M. (2017). PINGU: a vision for neutrino and particle physics at the South Pole. Journal of Physics G: Nuclear and Particle Physics, 44(5), Article ID 054006.
Open this publication in new window or tab >>PINGU: a vision for neutrino and particle physics at the South Pole
Show others...
2017 (English)In: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 44, no 5, 054006Article in journal (Refereed) Published
Abstract [en]

The Precision IceCube Next Generation Upgrade (PINGU) is a proposed low-energy in-fill extension to the IceCube Neutrino Observatory. With detection technology modeled closely on the successful IceCube example, PINGU will provide a 6 Mton effective mass for neutrino detection with an energy threshold of a few GeV. With an unprecedented sample of over 60 000 atmospheric neutrinos per year in this energy range, PINGU will make highly competitive measurements of neutrino oscillation parameters in an energy range over an order of magnitude higher than long-baseline neutrino beam experiments. PINGU will measure the mixing parameters theta(23) and Delta m(32)(2), including the octant of theta(23) for a wide range of values, and determine the neutrino mass ordering at 3 sigma median significance within five years of operation. PINGU's high precision measurement of the rate of nu(T) appearance will provide essential tests of the unitarity of the 3 x 3 PMNS neutrino mixing matrix. PINGU will also improve the sensitivity of searches for low mass dark matter in the Sun, use neutrino tomography to directly probe the composition of the Earth's core, and improve IceCube's sensitivity to neutrinos from Galactic supernovae. Reoptimization of the PINGU design has permitted substantial reduction in both cost and logistical requirements while delivering performance nearly identical to configurations previously studied.

Keyword
neutrino oscillations, atmospheric neutrinos, IceCube Neutrino Observatory, PINGU
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-322098 (URN)10.1088/1361-6471/44/5/054006 (DOI)000399127900001 ()
Funder
Swedish Research CouncilSwedish Polar Research SecretariatSwedish National Infrastructure for Computing (SNIC)Knut and Alice Wallenberg FoundationGerman Research Foundation (DFG)Australian Research Council
Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-05-16Bibliographically approved
Barwick, S. W., Besson, D. Z., Burgman, A., Chiem, E., Hallgren, A., Hanson, J. C., . . . Yodh, G. (2017). Radio detection of air showers with the ARIANNA experiment on the Ross Ice Shelf. Astroparticle physics, 90, 50-68.
Open this publication in new window or tab >>Radio detection of air showers with the ARIANNA experiment on the Ross Ice Shelf
Show others...
2017 (English)In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 90, 50-68 p.Article in journal (Refereed) Published
Abstract [en]

The ARIANNA hexagonal radio array (HRA) is an experiment in its pilot phase designed to detect cosmogenic neutrinos of energies above 10(16) eV. The most neutrino-like background stems from the radio emission of air showers. This article reports on dedicated efforts of simulating and detecting the signals of cosmic rays. A description of the fully radio self-triggered data-set, the properties of the detected air shower signals in the frequency range of 100-500 MHz and the consequences for neutrino detection are given. 38 air shower signals are identified by their distinct waveform characteristics, are in good agreement with simulations and their signals provide evidence that neutrino-induced radio signals will be distinguishable with high efficiency in ARIANNA. The cosmic ray flux at a mean energy of 6.5(-1.0)(+1.2) x 10(17) eV is measured to be 1.1(-0.7)(+1.0) x 10(-16) eV(-1) km(-2) sr(-1) yr(-1) and one five-fold coincident event is used to illustrate the capabilities of the ARIANNA detector to reconstruct arrival direction and energy of air showers.

Keyword
Cosmic rays, Neutrinos, Radio emission, 98.70.Sa, 95.85.Ry, 95.55.Vj, 95.55.Jz
National Category
Astronomy, Astrophysics and Cosmology Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-322833 (URN)10.1016/j.astropartphys.2017.02.003 (DOI)000399848600006 ()
Funder
German Research Foundation (DFG), NE 2031/1-1Knut and Alice Wallenberg Foundation
Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2017-06-08Bibliographically approved
Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., . . . Zoll, M. (2017). Search for annihilating dark matter in the Sun with 3 years of IceCube data. European Physical Journal C, 77, Article ID 146.
Open this publication in new window or tab >>Search for annihilating dark matter in the Sun with 3 years of IceCube data
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, 146Article in journal (Refereed) Published
Abstract [en]

We present results from an analysis looking for darkmatter annihilation in the Sun with the IceCube neutrino telescope. Gravitationally trapped dark matter in the Sun's core can annihilate into Standard Model particles making the Sun a source of GeV neutrinos. IceCube is able to detect neutrinos with energies > 100 GeV while its low-energy infill array DeepCore extends this to >10GeV. This analysis uses data gathered in the austral winters between May 2011 and May 2014, corresponding to 532 days of livetime when the Sun, being below the horizon, is a source of up-going neutrino events, easiest to discriminate against the dominant background of atmospheric muons. The sensitivity is a factor of two to four better than previous searches due to additional statistics and improved analysis methods involving better background rejection and reconstructions. The resultant upper limits on the spin-dependent dark matter-proton scattering cross section reach down to 1.46 x 10(-5) pb for a dark matter particle of mass 500GeV annihilating exclusively into tau(+)tau(-) particles. These are currently the most stringent limits on the spin-dependent dark matter-proton scattering cross section for WIMP masses above 50GeV.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-322850 (URN)10.1140/epjc/s10052-017-4689-9 (DOI)000400016600001 ()
Funder
Swedish Research CouncilSwedish Polar Research SecretariatSwedish National Infrastructure for Computing (SNIC)Knut and Alice Wallenberg FoundationGerman Research Foundation (DFG)Australian Research CouncilDanish National Research Foundation
Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-06-07Bibliographically approved
Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., . . . Zoll, M. (2017). Search for Astrophysical Sources of Neutrinos Using Cascade Events in IceCube. Astrophysical Journal, 846(2), Article ID 136.
Open this publication in new window or tab >>Search for Astrophysical Sources of Neutrinos Using Cascade Events in IceCube