699 research outputs found
Active Galactic Nuclei with Starbursts: Sources for Ultra High Energy Cosmic Rays
Ultra high energy cosmic ray events presently show a spectrum, which we
interpret here as galactic cosmic rays due to a starburst in the radio galaxy
Cen A pushed up in energy by the shock of a relativistic jet. The knee feature
and the particles with energy immediately higher in galactic cosmic rays then
turn into the bulk of ultra high energy cosmic rays. This entails that all
ultra high energy cosmic rays are heavy nuclei. This picture is viable if the
majority of the observed ultra high energy events come from the radio galaxy
Cen A, and are scattered by intergalactic magnetic fields across most of the
sky.Comment: 4 pages, 1 figure, proceedings of "High-Energy Gamma-rays and
Neutrinos from Extra-Galactic Sources", Heidelber
Observing gravitational wave bursts in pulsar timing measurements
We propose a novel method for observing the gravitational wave signature of
super-massive black hole (SMBH) mergers. This method is based on detection of a
specific type of gravitational waves, namely gravitational wave burst with
memory (BWM), using pulsar timing. We study the unique signature produced by
BWM in anomalous pulsar timing residuals. We show that the present day pulsar
timing precision allows one to detect BWM due to SMBH mergers from distances up
to 1 Gpc (for case of equal mass 10^8 Msun SMBH). Improvements in precision of
pulsar timing together with the increase in number of observed pulsars should
eventually lead to detection of a BWM signal due to SMBH merger, thereby making
the proposed technique complementary to the capabilities of the planned LISA
mission.Comment: 9 pages, 1 figure, generally matches the MNRAS versio
Quantum Black Holes from Cosmic Rays
We investigate the possibility for cosmic ray experiments to discover
non-thermal small black holes with masses in the TeV range. Such black holes
would result due to the impact between ultra high energy cosmic rays or
neutrinos with nuclei from the upper atmosphere and decay instantaneously. They
could be produced copiously if the Planck scale is in the few TeV region. As
their masses are close to the Planck scale, these holes would typically decay
into two particles emitted back-to-back. Depending on the angles between the
emitted particles with respect to the center of mass direction of motion, it is
possible for the simultaneous showers to be measured by the detectors.Comment: 6 pages, 3 figure
- …