Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the ...search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 1020 eV and 1013 eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos. The outline of this review is as follows: Introduction Why kilometer-scale detectors? Cosmic neutrinos associated with the highest energy cosmic rays High energy neutrino telescopes: methodologies of neutrino detection High energy neutrino telescopes: status
Cosmogenic neutrinos originate from photo-hadronic interactions of cosmic ray protons with the cosmic microwave background (CMB). The neutrino production rate can be constrained through the ...accompanying electrons, positrons and gamma-rays that quickly cascade on the CMB and intergalactic magnetic fields to lower energies and generate a
γ-ray background in the GeV–TeV region. Bethe–Heitler pair production by protons also contributes to the cascade and can tighten the neutrino constraints in models where extragalactic cosmic rays begin to dominate over the galactic component at a relatively low “crossover” energy. We investigate this issue in the light of the recent Fermi-LAT measurements of the diffuse extragalactic
γ-ray background and illustrate by a fit to the HiRes spectrum how the prediction of the cosmogenic neutrino flux in all-proton models varies with the crossover energy. The neutrino flux is required to be smaller when the gamma-ray bound is applied, nevertheless such models are still consistent with HiRes and Fermi-LAT if one properly takes into account the energy uncertainty of cosmic ray measurements. The presently allowed flux is within reach of the IceCube neutrino telescope and other dedicated radio experiments.
In light of the recent IceCube evidence for a flux of extraterrestrial neutrinos, we revisit the prospect of observing the sources of the Galactic cosmic rays. In particular, we update the ...predictions for the neutrino flux expected from sources in the nearby star-forming region in Cygnus taking into account recent TeV gamma ray measurements of their spectra. We consider the three Milagro sources: MGRO J2019+37, MGRO J1908+06 and MGRO J2031+41 and calculate the attainable confidence level limits and statistical significance as a function of the exposure time. We also evaluate the prospects for a kilometer-scale detector in the Mediterranean to observe and elucidate the origin of the cosmic neutrino flux measured by IceCube.
► We study the hypothesis that GRBs are the main sources of UHE CRs. ► Our analysis focuses on UHE CR emission in the form of neutrons produced in photo-pion interactions. ► We calculate the ...associated neutrino spectra by a fit to HiRes data. ► We show that these diffuse neutrino fluxes are challenged by recent upper limits from IceCube. ► This serves as a probe of viable GRB sources in this UHE CR scenario.
Gamma ray burst (GRB) fireballs provide one of very few astrophysical environments where one can contemplate the acceleration of cosmic rays to energies that exceed 10
20
eV. The assumption that GRBs are the sources of the observed cosmic rays generates a calculable flux of neutrinos produced when the protons interact with fireball photons. With data taken during construction IceCube has already reached a sensitivity to observe neutrinos produced in temporal coincidence with individual GRBs provided that they are the sources of the observed extra-galactic cosmic rays. We here point out that the GRB origin of cosmic rays is also challenged by the IceCube upper limit on a possible diffuse flux of cosmic neutrinos which should not be exceeded by the flux produced by all GRB over Hubble time. Our alternative approach has the advantage of directly relating the diffuse flux produced by all GRBs to measurements of the cosmic ray flux. It also generates both the neutrino flux produced by the sources and the associated cosmogenic neutrino flux in a synergetic way.
Context.
Tensions between the diffuse gamma-ray sky observed by the
Fermi
Large Area Telescope (
Fermi
-LAT) and the diffuse, high-energy neutrino sky detected by the IceCube South Pole Neutrino ...Observatory raise questions about our knowledge of high-energy neutrino sources in the gamma-ray regime. While blazars are among the most energetic persistent particle accelerators in the Universe, studies suggest that they could account for up to 10–30% of the neutrino flux measured by IceCube.
Aims.
Our recent results highlight that the associated IceCube neutrinos arrived in a local gamma-ray minimum (dip) of three strong neutrino point-source candidates. Here, we increase the sample of neutrino-source candidates in order to study their gamma-ray light curves.
Methods.
We generated the one-year
Fermi
-LAT light curve for eight neutrino-source candidate blazars (RBS 0958, GB6 J1040+0617, PKS 1313-333, TXS 0506+056, PKS 1454-354, NVSS J042025-374443, PKS 0426-380, and PKS 1502+106), centered on the detection time of the associated IceCube neutrinos. We applied the Bayesian block algorithm to the light curves to characterize their variability.
Results.
Our results indicate that GB6 J1040+0617 was in a phase of high gamma-ray activity, while none of the other seven neutrino-source candidates were statistically bright during the detection of the corresponding neutrinos; indeed, most of the time neutrinos arrived in a faint gamma-ray phase of the light curves. This suggests either that the eight source candidate blazars (associated with seven neutrino events) in our reduced sample are not the sources of the corresponding IceCube neutrinos, or that an in-source effect (e.g., the suppression of gamma rays due to high gamma-gamma opacity) complicates the multimessenger scenario of neutrino emission for these blazars.
Sterile neutrinos and IceCube Halzen, F
Journal of physics. Conference series,
01/2013, Letnik:
408, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Although the framework for oscillations of the three neutrino flavors in the Standard Model has been convincingly established, indications persist that it may be incomplete. Challenges are coming ...from the LSND and MiniBooNe short-baseline experiments, from the neutrino sources used in the Gallex and Sage solar neutrino experiments and, more recently, from an a-posteriori analysis of reactor neutrino experiments. One way to accommodate the reported "anomalies", if real, is to introduce one or more sterile neutrinos in the mass range δm2 ~ 1eV2. TeV atmospheric neutrinos propagating through the Earth undergo resonant oscillations in the presence of sterile neutrinos; a clear signature in a neutrino telescope like IceCube is the the change in shape of the zenith-energy distribution of the atmospheric neutrinos. IceCube detects more than 100,000 atmospheric neutrinos per year. Statistics do not limit such a measurement, but the uncertainties in modeling the expectations of the conventional 3-flavor scenario, including the systematics of the detector, do. We review the status and future perspectives of understanding the zenith and energy response of IceCube in the TeV energy range.
We estimate the neutrino emission from individual γ-ray bursts observed by the BATSE detector on the Compton Gamma-Ray Observatory. Neutrinos are produced by photoproduction of pions when protons ...interact with photons in the region where the kinetic energy of the relativistic fireball is dissipated allowing the acceleration of electrons and protons. We also consider models where neutrinos are predominantly produced on the radiation surrounding the newly formed black hole. From the observed redshift and photon flux of each individual burst, we compute the neutrino flux in a variety of models based on the assumption that equal kinetic energy is dissipated into electrons and protons. Where not measured, the redshift is estimated by other methods. Unlike previous calculations of the universal diffuse neutrino flux produced by all γ-ray bursts, the individual fluxes (compiled at
http://www.arcetri.astro.it/~dafne/grb/) can be directly compared with coincident observations by the AMANDA telescope at the South Pole. Because of its large statistics, our predictions are likely to be representative for future observations with larger neutrino telescopes.
We report the measurement of muons and muon-induced phosphorescence in DM-Ice17, a NaI(Tl) direct detection dark matter experiment at the South Pole. Muon interactions in the crystal are identified ...by their observed pulse shape and large energy depositions. The measured muon rate in DM-Ice17 is 2.93+ or -0.04 mu /crystal/day with a modulation amplitude of 12.3+ or -1.7%, consistent with expectation. Following muon interactions, we observe long-lived phosphorescence in the NaI(Tl) crystals with a decay time of 5.5+ or -0.5s. The prompt energy deposited by a muon is correlated to the amount of delayed phosphorescence, the brightest of which consist of tens of millions of photons. These photons are distributed over tens of seconds with a rate and arrival timing that do not mimic a scintillation signal above 2keV sub(ee). While the properties of phosphorescence vary among individual crystals, the annually modulating signal observed by DAMA cannot be accounted for by phosphorescence with the characteristics observed in DM-Ice17.
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