Speaker
Keith Bechtol
Description
Galaxy clusters are expected to behave as reservoirs of
cosmic-ray nuclei over billion-year timescales, thus
creating a record of their non-thermal history since the
time of their formation. One source population of such
intergalactic cosmic rays are those initially accelerated in
the galaxies themselves, which subsequently escape the
interstellar medium of their parent galaxies. Gamma-ray
telescopes allow us to study the acceleration and transport
of cosmic-ray nuclei throughout our Milky Way and in
external galaxies via photons created by the inelastic
collisions of hadronic cosmic rays with ambient interstellar
gas. I will discuss observations and analysis of
non-AGN-dominated galaxies performed with the Large Area
Telescope on the Fermi Gamma-ray Space Telescope, and
suggest means by which these observations can be used to
estimate the contributions of galaxies to the non-thermal
hadrons of the intergalactic medium.
