Origin of Cosmic Rays
Supernova remnants are considered the major source of galactic cosmic rays. The connection between cosmic rays and supernovas was first suggested by Walter Baade and Fritz Zwicky in 1934. Vitaly Ginzburg and Sergei Syrovatskii in 1964 remarked that if the efficiency of cosmic ray acceleration in supernova remnants is about 10 percent, the cosmic ray losses of the Milky Way are compensated. This hypothesis is supported by a specific mechanism called "shock wave acceleration" based on Enrico Fermi's ideas, which is still under development.
Indeed, Enrico Fermi proposed in 1949 a model for the acceleration of cosmic rays through particle collisions with magnetic clouds in the interstellar medium. This process, known as the "Second Order Fermi Mechanism", increases particle energy during head-on collisions, resulting in a steady gain in energy. A later model to produce Fermi Acceleration was generated by a powerful shock front moving through space. Particles that repeatedly cross the front of the shock can gain significant increases in energy. This became known as the "First Order Fermi Mechanism".
Supernova remnants can provide the energetic shock fronts required to generate ultra-high energy cosmic rays. Observation of the SN 1006 remnant in the X-ray has shown synchrotron emission consistent with it being a source of cosmic rays. However, for energies higher than about 1015 eV a different mechanism is required as supernova remnants cannot provide sufficient energy.
It is still unclear whether supernova remnants accelerate cosmic rays up to PeV energies. The future telescope CTA will help to answer this question.
Read more about this topic: Supernova Remnant
Famous quotes containing the words origin of, origin, cosmic and/or rays:
“The essence of morality is a questioning about morality; and the decisive move of human life is to use ceaselessly all light to look for the origin of the opposition between good and evil.”
—Georges Bataille (1897–1962)
“Someone had literally run to earth
In an old cellar hole in a byroad
The origin of all the family there.
Thence they were sprung, so numerous a tribe
That now not all the houses left in town
Made shift to shelter them without the help
Of here and there a tent in grove and orchard.”
—Robert Frost (1874–1963)
“A cosmic loneliness was my shadow.”
—Zora Neale Hurston (1891–1960)
“The spirit of God, like the sun, always gives all its light at once. The spirit of man resembles the pale moon, which has its phases, its absences and its returns, its lucidity and its spots, its fullness and its disappearance, which borrows all its light from the rays of the sun, and which still dares to intercept them on occasion.”
—Victor Hugo (1802–1885)