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High Energy Astrophysics and Pulsars

High Energy Astrophysics and Pulsars

Course Outline: 

The Universe is not only visible through radio, optical or X-ray “eyes”, but also through gamma-ray “eyes”. In fact, the gamma-ray spectral range alone covers more decades in energy or frequency compared to the eleven decades in energy covered between radio waves and hard X-rays alone. The ideal course in High Energy Astrophysics and Pulsars should rely on the knowledge built up during the Honors courses. However, for 2003, we will have to assume that the proper foundations are less ideal, in which case relevant material from some Honors courses will be duplicated. There are several ways to probe high-energy processes: through the direct measurement of high-energy particles, or cosmic rays, and the direct measurement of non-thermal emission in the radio, optical, X-rays up to the gamma-ray range (as shown in this picture of the broad-band spectrum of the Crab Nebula or Messier 1). In the case of pulsars, we find that this emission is associated with rapidly rotating neutron stars, which accelerate charged particles as a result of the dynamo processes. Particle acceleration occurs in our galaxy, as well as in extragalactic objects. This course will cover the fundamental principles of this process in a few types of cosmic sources. Those accelerated particles, which escape from a source, finally contribute to the bulk of cosmic rays in our galaxy, and some of these particles are detectable at earth. The second part of the course concentrates on neutron stars and pulsars: Emphasis is given in their properties, observable phenomena, their interior structure, as well as the magnetosphere with associated particle acceleration leading to pulsed gamma-ray emission.

Syllabus: 

  • Historical perspective of high-energy astrophysics.
  • Stellar evolution relevant to high-energy astrophysics: final stages of stellar evolution.
  • Universal particle acceleration: Galactic and extragalactic.
  • Interaction of high-energy particles with matter: Bremsstrahlung and spallation products.
  • Interaction of electrons with magnetic fields: synchrotron and curvature radiation.
  • Interaction of electrons with photons: Compton scattering - Thomson & Klein-Nishina limits.
  • Interstellar gas, magnetic field and associated galactic non-thermal radiation.
  • Origin of electrons in our galaxy: supernova remnants and gamma-ray visibility.
  • Basic properties of pulsars and neutron star astrophysics.
  • Neutron star interiors.
  • Glitches as probes of neutron star interiors.
  • Pulsar magnetospheres.
  • X-ray and gamma-ray emission from pulsars.

References:

  • Longair, M. S., High Energy Astrophysics: Vol. 1, 1992, (Particles, photons and their detection) & Vol 2, 1994, (Stars, the Galaxy and the interstellar medium),
    Cambridge University Press, ISBN 0 521 38773 & ISBN 0 521 43584 6.
  • Blandford, R.D., Hewish, A., Lyne, A.G., & Mestel, L. 1992, Pulsars as Physics Laboratories, The Royal Society, Oxford University Press, ISBN 0 19 853983 5.
  • Mészáros, P. 1992, High-Energy Radiation from Magnetized Neutron Stars, The University of Chicago Press, Chicago & London, ISBN 0 226 52094 3.


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Programmes | by Dr. Radut