Search for dissertations about: "Gamma ray"

Showing result 1 - 5 of 122 swedish dissertations containing the words Gamma ray.

  2. 1. Photospheric emission in gamma ray bursts : Analysis and interpretation of observations made by the Fermi gamma ray space telescope

    Author : Shabnam Iyyani; Felix Ryde; David Burrows; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; gamma ray bursts; photosphere; radiation mechanism; Theoretical Physics; teoretisk fysik;

    Abstract : The large flashes of radiation that are observed in GRBs are generally believed to arise in a relativistic jetted outflow. This thesis addresses the question of how and where in the jet this radiation is produced. READ MORE

  4. 2. Gamma-Ray Emission from Galaxy Clusters : DARK MATTER AND COSMIC-RAYS

    Author : Anders Pinzke; Lars Bergström; Olaf Reimer; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Galaxy clusters; gamma-rays; cosmic-rays; dark matter; High energy astrophysics; Högenergiastrofysik; teoretisk fysik; Theoretical Physics;

    Abstract : The quest for the first detection of a galaxy cluster in the high energy gamma-ray regime is ongoing, and even though clusters are observed in several other wave-bands, there is still no firm detection in gamma-rays. To complement the observational efforts we estimate the gamma-ray contributions from both annihilating dark matter and cosmic-ray (CR) proton as well as CR electron induced emission. READ MORE

  5. 3. Multi-messenger emission from gamma-ray bursts

    Author : Filip Samuelsson; Felix Ryde; Peter Mészáros; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; astrophysics; gamma-ray bursts; cosmic rays; Atomic; Subatomic and Astrophysics; Atomär fysik; subatomär fysik och astrofysik;

    Abstract : Multi-messenger astronomy is a very hot topic in the astrophysical community. A messenger is something that carries information. Different astrophysical messenger types are photons, cosmic rays, neutrinos, and gravitational waves. They all carry unique and complementary information to one another. READ MORE

  6. 4. Microphysical Conditioning of Gamma-Ray Burst Shocks

    Author : Jacob Trier Frederiksen; Claes Fransson; Åke Nordlund; Mikhail V. Medvedev; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; magnetic fields; particle acceleration; plasma instabilities; gamma-ray bursts; collisionless shocks; relativistic outflows; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; astronomi;

    Abstract : Gamma-Ray Bursts (GRBs) are believed to be connected with either collapse of massive stars or – in some cases – coalescing neutron stars, both of which cause extreme relativistic explosions observable from the entire Universe. GRBs produce rapid flashes of high energy radiation, extending up to 2MeV in photon energies: as much energy per photon as the rest mass of 4 electrons. READ MORE

  7. 5. Interpretation of gamma-ray burst X-ray and optical afterglow emission : From the central engine to the circumburst interaction

    Author : Liang Li; Felix Ryde; Fawad Hassan; Kim Page; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; gamma-ray bursts; central engine; afterglow; teoretisk fysik; Theoretical Physics;

    Abstract : Gamma-ray bursts are the largest electromagnetic explosions known to happen in the Universe and are associated with the collapse of stellar progenitors into blackholes. After an energetic prompt emission phase, lasting typically less than a minute and emitted in the gamma-rays, a long-lived afterglow phase starts. READ MORE