Weakly interacting neutrinos are ideal astronomical messengers because they travel through space without deflection by magnetic fields and, essentially, without absorption. Their weak interaction ...also makes them notoriously difficult to detect, with observation of high-energy neutrinos from distant sources requiring kilometer-scale detectors. The IceCube project transformed a cubic kilometer of natural Antarctic ice at the geographic South Pole into a Cherenkov detector. It discovered a flux of cosmic neutrinos in the energy range from 10 TeV to 10 PeV, predominantly extragalactic in origin. Their corresponding energy density is close to that of high-energy photons detected by gamma-ray satellites and ultra-high-energy cosmic rays observed with large surface detectors. Neutrinos are therefore ubiquitous in the nonthermal universe, suggesting a more significant role of protons (nuclei) relative to electrons than previously anticipated. Thus, anticipating an essential role for multimessenger astronomy, IceCube is planning significant upgrades of the present instrument as well as a next-generation detector. Similar detectors are under construction in the Mediterranean Sea and Lake Baikal.
After updating the status of the measurements of the cosmic neutrino flux by the IceCube experiment, we summarize the evidence for the first identified source of cosmic rays and speculate on the ...connection between the two observations.
Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated ...fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field.
High‐Energy Neutrinos from the Cosmos Halzen, Francis
Annalen der Physik,
November 2021, 2021-11-00, 20211101, Volume:
533, Issue:
11
Journal Article
Peer reviewed
Open access
The IceCube project transformed a cubic kilometer of transparent natural Antarctic ice into a Cherenkov detector. It discovered PeV‐energy neutrinos originating beyond our galaxy with an energy flux ...that is comparable to that of GeV‐energy gamma rays and EeV‐energy cosmic rays. These neutrinos provide the only unobstructed view of the cosmic accelerators that power the highest energy radiation reaching us from the universe. The results from IceCube's first decade of operations, foremost the measurement of the diffuse neutrino flux from the universe using multiple techniques is reviewed. The multimessenger data that identified the supermassive black hole TXS 0506+056 as a source of cosmic neutrinos is subsequently reviewed and attention is drawn to accumulating indications that cosmic neutrinos are associated with gamma‐ray‐obscured active galaxies, that is, the energy in gamma rays that accompanies cosmic neutrinos emerges at MeV energies, or below. Reaching beyond 10 PeV energy, cosmic neutrinos provide a natural beam to study neutrinos themselves.
The IceCube Neutrino Observatory is the first detector of its kind, designed to observe the cosmos from deep within the South Pole ice. It consists of a cubic kilometer of instrumented transparent ice transformed into a Cherenkov detector. IceCube's first decade of operations has yielded breakthrough results, including the discovery of very high energy cosmic neutrinos.
We describe the pioneering contributions of Thomas K. Gaisser to the birth and development of particle astrophysics, a new field of research at the intersection of cosmic ray physics, astronomy, ...astrophysics, and particle physics that has emerged in the last few decades. We will especially focus on his studies of natural beams of neutrinos: those generated by the interactions of cosmic rays in the Earth’s atmosphere and those emitted by astrophysical sources. Tom actively participated in the discovery of these cosmic neutrinos as well. His contributions also extend to gamma-ray astronomy, the study of the cosmic ray spectra and composition, and the modeling of cosmic ray interactions in the atmosphere and in astrophysical environments. Tom invariably focused his research on the theoretical and phenomenological problems of greatest interest at the time, producing frameworks that transparently interpreted often complex data. These studies have been very influential and have shaped the development of the field.
Neutrino Astronomy
The IceCube Neutrino Observatory is designed to observe the cosmos from deep within the South Pole ice. In article number 2100309, Francis Halzen reviews the results from IceCube's ...first decade of operations. The cover image illustrates the light pattern recorded by IceCube that is radiated by a particle shower created by the Glashow resonance. Colored dots represent light sensors that detect photons. Their color indicates arrival time, from red (early) to purple (late) following the rainbow, and their size reflects the number of photons detected.
ABSTRACT The energy density of cosmic neutrinos measured by IceCube matches the one observed by Fermi in extragalactic photons that predominantly originate in blazars. This has inspired attempts to ...match Fermi sources with IceCube neutrinos. A spatial association combined with a coincidence in time with a flaring source may represent a smoking gun for the origin of the IceCube flux. In 2015 June, the Fermi Large Area Telescope observed an intense flare from blazar 3C 279 that exceeded the steady flux of the source by a factor of 40 for the duration of a day. We show that IceCube is likely to observe neutrinos, if indeed hadronic in origin, in data that are still blinded at this time. We also discuss other opportunities for coincident observations that include a recent flare from blazar 1ES 1959+650 that previously produced an intriguing coincidence with AMANDA observations.
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