Download Gamma-Ray Bursts

Arne Rau
Gamma-Ray Bursts: The Brightest Explosions in the Universe
Ranking second only behind the Big Bang, Gamma-ray bursts (GRBs) are the most luminous
explosions known to occur in our Universe. These milliseconds to minutes lasting flashes of
gamma-ray photons, the most energetic form of light, release as much energy in their short
duration as our Sun will in its entire lifetime. Two classes of GRBs have been identified, with a
dividing line in the gamma-ray emission duration of about 2 seconds.The shorter events are
thought to beassociated with a merger in some rare stellar systems, possibly two neutron stars
(extremely dense and hot stars composed almost entirely of neutrons). The longer events arise
during the particularly violent deaths of a rapidly rotating, high-mass stars which collapse to form
black holes and produce a supernovae.
The initial burst of gamma-rays is usually followed by a longer-lived "afterglow" emitting over a
wide range of the electro-magnetic spectrum, from X-rays, over ultraviolet, optical, and infrared
light, to radio wavelengths. This component has been extremely valuable for understanding the
origin of GRBs and the galaxies in which they are located. We now know that GRBs originated
from outside our own Galaxy, from relatively nearby galaxies to the earliest moments of our
Universe.They open a new window to address important questions of astrophyics, e.g., the
formation and evolution of the first galaxies and stars. GRB observations have also been applied
to resolve fundamental problems of physics, such as the possible variation of photon speed with
energy (so-called Lorentz invariance, a central component of Einstein's special theory of
relativity).
In my talk I will present the GRB phenomenon, and in particular highlight some of the most
recent discoveries from the Fermi and Swift satellites.
References:

Vedrenne, G., & Atteia, J.-L., 2008, Gamma-Ray Bursts: The brightest
explosions in the Universe (Springer-Praxis Books), Springer, Berlin

Zhang, B., & Meszaros, P., 2004, Gamma-Ray Bursts: Progress, Problems& Prospects,
International Journal of Modern Physics A, Volume: 19, Issue: 15(2004) pp. 23852472