Browsing NTNU Open by Author "Kachelriess, Michael"

Now showing items 21-40 of 51

    • Flavor Oscillations of High-Energy Neutrinos 

      Sánchez Navas, Sergio (Master thesis, 2016)
      In this thesis, we study neutrino oscillations in vacuum and in the presence of a Dark Matter halo in the Milky Way. For that purpose, first describe the particle physics of neutrinos through an historical introduction. ...

    • Formation models for cosmic ray antinuclei 

      Kachelriess, Michael; Ostapchenko, Sergey; Tjemsland, Jonas (Peer reviewed; Journal article, 2022)
      The expected low background of light antinuclei, such as antideuteron and antihelium-3, makes them ideal detection channels for exotic physics, such as dark matter annihilations. At the same time, their small binding ...

    • Gamma-ray counterpart of the IceCube neutrinos 

      Kachelriess, Michael; Neronov, Andrii Yu.; Semikoz, Dimitry V. (Journal article; Peer reviewed, 2019)
      A γ-ray excess at high Galactic latitudes starting at energies 300 GeV was recently discovered in the data of the Fermi telescope. The multi-TeV γ-ray emission found has spectral characteristics at both low and high Galactic ...

    • High energy radiation from Centaurus A 

      Kachelriess, Michael; Ostapchenko, Sergey; Tomas, R (Journal article; Peer reviewed, 2009)
      We calculate, for the nearest active galactic nucleus (AGN), Centaurus A (Cen A), the flux of high-energy cosmic rays (CR) and of accompanying secondary photons and neutrinos expected from hadronic interactions in the ...

    • High-energy astrophysical neutrinos from interactions in the Local Bubble 

      Kachelriess, Michael; Semikoz, Dimitry; Bouyahiaoui, Makarim (Journal article; Peer reviewed, 2020)
      A signal of high-energy extraterrestrial neutrinos was discovered by the IceCube experiment [1]. Neutrinos are always produced together with gamma-rays, but the gamma-ray flux from extra- galactic sources cascade down to ...

    • High-energy Neutrinos from Galactic Superbubbles 

      Andersen, Karen-Johanne; Kachelriess, Michael; Semikoz, DV (Peer reviewed; Journal article, 2018)
      We study the propagation of cosmic rays (CRs) generated by sources residing inside superbubbles. We show that the enhanced magnetic field in the bubble wall leads to an increase in the interior CR density. Because of the ...

    • Implementasjon av Tredimensjonale Elektromagnetiske Kaskader i Elmag 

      Blytt, Markus Henrikssønn (Master thesis, 2019)
      En oppdatert versjon av Monte Carlo programmet ELMAG er presentert. Programmet simulerer elektromagnetiske kaskader som startes av høyenergiske fotoner fra blasarer. De høyenergiske fotonene vekselvirker med bakgrunnsfotoner ...

    • Inside out: unveiling local interstellar spectra of cosmic ray species 

      Boschini, M.J.; Della Torre, S.; Gervasi, M.; Grandi, D.; Johannesson, G.; Kachelriess, Michael; La Vacca, G.; Masi, N.; Moskalenko, I. V.; Orlando, E.; Ostapchenko, S. S.; Pensotti, S.; Porter, T. A.; Quadrani, L.; Rancoita, P. G.; Rozza, D.; Tacconi, M. (Journal article; Peer reviewed, 2018)
      Local interstellar spectra (LIS) for protons, helium and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and Heliosphere. Two propagation ...

    • Maximum Likelihood Analysis of IceCube Data: - Could Decaying Dark Matter explain the high energy Neutrino Excess? 

      Leinaas, Jan Erik (Master thesis, 2015)
      In this theoretical physics master thesis I've looked at a set of observations from a neutrino observatory in Antarctica called IceCube. This observatory has observed more high energy neutrinos than expected. I wanted to ...

    • Meson production in air showers and the search for light exotic particles 

      Kachelriess, Michael; Tjemsland, Jonas (Peer reviewed; Journal article, 2021)
      Decays of mesons produced in cosmic ray induced air showers in Earth’s atmosphere can lead to a flux of light exotic particles which can be detected in underground experiments. We evaluate the energy spectra of the light ...

    • New Calculation of Secondary Antiprotons in Cosmic Rays 

      Moskalenko, Igor V.; Jóhannesson, Gudlaugur; Kachelriess, Michael; Orlando, E; Ostapchenko, Sergey; Porter, T.A. (Peer reviewed; Journal article, 2016)
      A dramatic increase in the accuracy and statistics of space-borne cosmic ray (CR) measurements has yielded several breakthroughs over the last several years. The most puzzling is the rise in the positron fraction above 10 ...

    • Nuclear coalescence and collective behaviour in small interacting systems 

      Kachelriess, Michael; Ostapchenko, Sergey; Tjemsland, Jonas (Peer reviewed; Journal article, 2022)
      The production of light nuclei in particle collisions can be described as the coalescence of nucleons into nuclei. In most coalescence models used in heavy ion collisions, the probability for coalescence is controlled ...

    • Nuclear coalescence, collective behaviour and emission volume in small interacting systems 

      Kachelriess, Michael; Ostapchenko, Sergey (Peer reviewed; Journal article, 2022)
      The production of light nuclei and antinuclei in particle collisions can be described as the coalescence of final state nucleons that are close in phase space. In heavy ion collisions, it is usually assumed that the formation ...

    • Numerical studies of Supernova Remnants 

      Andresen, Haakon (Master thesis, 2013)
      Supernovae are very luminous events, on the scale of entire galaxies, and deposit mass and large amounts of energy in to the surrounding interstellar medium. In this workthe effect of a supernova on the surrounding medium ...

    • Particle Production in Gravitational Fields 

      Bauer, Dag-Vidar Krogstad (Master thesis, 2013)
      In this thesis, we discuss the phenomenon of particle production in gravitational fields. We present the general framework in flat Friedmann-Robertson-Walker spacetimes and apply it to an asymptotically static model in two ...

    • Photon-ALP oscillations at CTA energies 

      Kachelriess, Michael; Tjemsland, Jonas (Peer reviewed; Journal article, 2023)
      Axions and axion-like-particles (ALPs) are well motivated beyond the standard model particles that can explain a variety of unsolved problems in physics, such as the strong CP problem and the nature of dark matter. These ...

    • Photon-ALP oscillations at TeV energies 

      Kachelriess, Michael; Tjemsland, Jonas (Peer reviewed; Journal article, 2022)
      Axion and axion-like-paricles (ALPs) are well motivated cold dark matter candidates. Nevertheless, an astoundingly huge parameter space remains unexplored despite much effort, ranging from fuzzy dark matter at ma∼10−22 eV ...

    • Photon-ALP oscillations with ELMAG 

      Kachelriess, Michael; Tjemsland, Jonas (Peer reviewed; Journal article, 2022)
      ELMAG is a Monte Carlo program made to simulate electromagnetic cascades initiated by high-energy photons interacting with the extragalactic background light. Photons propagating in an external magnetic field may oscillate ...

    • Plasma Instabilities in Electron-Positron Pair Beams from Blazars 

      Hornkjøl, Martin (Master thesis, 2018)
      The non-detection of an electromagnetic cascade in the electron-positron plasma beams from blazars has led many physicists to invoke an intergalactic magnetic eld that de ects charged particles away from our eld of view. ...

    • Probing dark matter with astroparticles 

      Tjemsland, Jonas (Doctoral theses at NTNU;2023:240, Doctoral thesis, 2023)
      There is an enormous amount of evidence for the existence of dark matter, from scales ranging from the faintest dwarf galaxies to the Universe as a whole. However, its nature remains a mystery. This thesis is a part of the ...