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#icecube

2 posts2 participants0 posts today
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Stephen Sekula

It’s been a wonderful first half-day in #MadisonWI. We got to check out some of the old stomping grounds from our time in graduate school 25 years ago, especially State Street and the Capitol Square. We spent some time at the #Wisconsin #IceCube Particle #Astrophysics Center (WIPAC) and met with colleagues of ours there. It’s good to be in our academic home, where we first met.

I am excited for @jodi’s #colloquium in the #Physics Department tomorrow afternoon!

wipac.wisc.edu/

The Wisconsin State Capitol Building
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MPI für Radioastronomie

Three weeks ago, the scientific journal Nature @nature reported the discovery of the most energetic #neutrino ever observed. Its energy is 16,000 times greater than the strongest particle collisions created by the Large Hadron Collider and corresponds to 30 times the energy needed to press a computer key.

The neutrino was discovered in an underwater observatory in the Mediterranean, one of three neutrino detectors in water - two in the Mediterranean and one at Lake Baikal. At the geographic South Pole, there is the #IceCube neutrino detector under the ice. Other detectors exist underground in China, Italy, and Japan.

All these #detectors are not located on the Earth's surface because the Earth itself acts like a #telescope for neutrinos. Neutrinos are extremely light, electrically neutral particles that interact very weakly with matter and pass through the Earth. When they collide with atomic nuclei, charged particles are produced that move faster than light in water or ice, emitting blue light that is captured.

Water and ice are ideal media for detecting neutrinos because they provide large volumes to detect these particles while shielding against cosmic radiation and other disturbances. IceCube even utilizes 1 cubic kilometer of ice.

Neutrinos are the second most abundant particles in the universe, after photons, but are difficult to study because they interact so little with matter. Interestingly, dark matter and dark energy, which make up 95% of the universe, also interact very weakly with normal matter, while the remaining 5% consists of elements like #hydrogen and #helium, of which only 0.5% is visible matter (such as #stars).

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MPI für Radioastronomie

Vor drei Wochen berichtete die Fachzeitschrift Nature @nature über die Entdeckung des energiereichsten jemals beobachteten #Neutrinos. Seine Energie ist 16.000 Mal größer als die stärksten #Teilchenkollisionen des Large Hadron Colliders und entspricht dem 30-fachen der Energie, die zum Drücken einer Computertaste nötig ist.

Das Neutrino wurde in einem #Unterwasserobservatorium im Mittelmeer entdeckt, eines von insgesamt drei Neutrino-Detektoren im Wasser – zwei im Mittelmeer und einer am Baikalsee. Am geografischen Südpol gibt es den Neutrino-Detektor #IceCube unter dem Eis. Weitere Detektoren existieren unterirdisch in China, Italien und Japan.

Alle diese Detektoren befinden sich nicht auf der Erdoberfläche, da die Erde selbst wie ein #Teleskop für Neutrinos wirkt. Neutrinos sind extrem leichte, elektrisch neutrale #Teilchen, die kaum mit Materie wechselwirken und durch die Erde hindurchgehen. Bei Kollisionen mit Atomkernen entstehen geladene Teilchen, die schneller als Licht in Wasser oder Eis bewegen und dabei blaues Licht erzeugen, das erfasst wird.

Wasser und Eis sind ideale Medien, um Neutrinos nachzuweisen, da sie große Volumen bieten, um diese Teilchen zu entdecken und gleichzeitig kosmische Strahlung und Störungen abzuschirmen. IceCube nutzt sogar 1 Kubikkilometer Eis.

Neutrinos sind die zweithäufigsten Teilchen im #Universum, nach Photonen, aber schwer zu verstehen, da sie so wenig mit Materie interagieren. Interessanterweise interagieren auch dunkle Materie und dunkle Energie, die 95 % des Universums ausmachen, kaum mit normaler Materie, während die restlichen 5 % aus Elementen wie #Wasserstoff und #Helium bestehen, wovon nur 0,5 % sichtbare #Materie (wie Sterne) sind.

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Daniel Fischer

VERITAS and multiwavelength observations of the #Blazar B3 2247+381 in response to an IceCube neutrino alert: arxiv.org/abs/2502.03853 -> #VERITAS follow-up observations of an #IceCube neutrino alert: icecube.wisc.edu/news/research

arXiv.orgVERITAS and multiwavelength observations of the Blazar B3 2247+381 in response to an IceCube neutrino alertWhile the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods used towards understanding this is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between May 20, 2022 and November 10, 2022. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is well described using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, and given the significance of the neutrino excess is at 3$σ$ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation.
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Sofasophia

Gibt es eigentlich auf #Icecube die Möglichkeit, die abonnierten Hashtags alphabetisch zu ordnen? Bei mir werden sie nach „neueste zuoberst“ gelistet, was nicht wirklich übersichtlich ist.
Danke für Tipps und/oder Teilen an die Macher*innen.

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