24 research outputs found
'Werner Buttner's Paintings: From 'Werner' to 'Art' and Back Again
Contribution to a monograph on noted German painter Werner Buttner
Origin of the highest energy cosmic rays observed
Introducing a simple Galactic wind model patterned after the solar wind we
show that back-tracing the orbits of the highest energy cosmic events suggests
that they may all come from the Virgo cluster, and so probably from the active
radio galaxy M87. This confirms a long standing expectation. Those powerful
radio galaxies that have their relativistic jets stuck in the interstellar
medium of the host galaxy, such as 3C147, will then enable us to derive limits
on the production of any new kind of particle, expected in some extensions of
the standard model in particle physics. New data from HIRES will be crucial in
testing the model proposed here.Comment: At TAUP99, the 6th international workshop on topics in Astroparticle
Physics and Underground Physics, College de France, Eds. J. Dumarchez, M.
Froissart, D. Vignaud, (Sep 1999
Centaurus A: the one extragalactic source of cosmic rays with energies above the knee
The origin of cosmic rays at all energies is still uncertain. In this paper
we present and explore an astrophysical scenario to produce cosmic rays with
energy ranging from below o eV. We show here that
just our Galaxy and the radio galaxy Cen A, each with their own galactic cosmic
ray particles, but with those from the radio galaxy pushed up in energy by a
relativistic shock in the jet emanating from the active black hole, are
sufficient to describe the most recent data in the energy range PeV to near
ZeV. Data are available over this entire energy range from the experiments
KASCADE, KASCADE-Grande and Pierre Auger Observatory. The energy spectrum
calculated here correctly reproduces the measured spectrum beyond the knee, and
contrary to widely held expectations, no other extragalactic source population
is required to explain the data, even at energies far below the general cutoff
expected at eV, the Greisen-Zatsepin-Kuzmin turn-off due to
interaction with the cosmological microwave background. We present several
predictions for the source population, the cosmic ray composition and the
propagation to Earth which can be tested in the near future
Cosmic ray transport and anisotropies
We show that the large-scale cosmic ray anisotropy at ~10 TeV can be
explained by a modified Compton-Getting effect in the magnetized flow field of
old supernova remnants. This approach suggests an optimum energy scale for
detecting the anisotropy. Two key assumptions are that propagation is based on
turbulence following a Kolmogorov law and that cosmic ray interactions are
dominated by transport through stellar winds of the exploding stars. A
prediction is that the amplitude is smaller at lower energies due to incomplete
sampling of the velocity field and also smaller at larger energies due to
smearing.Comment: 6 pages, 1 figur