Scattering of Hard γ-Rays and Annihilation Radiation

Elastic scattering of linearly polarized hard x - rays

INTEGRAL probes the morphology of the Crab nebula in hard X - rays / soft γ - rays

Aims. We use the IBIS/ISGRI telescope on board INTEGRAL to measure the position of the centroid of the 20-200 keV emission from the Crab region. Methods. We find that the astrometry of the IBIS telescope is affected by the temperature of the IBIS mask during the observation. After correcting for this effect, we show that the systematic errors on the astrometry of the telescope are of the order ...

TeV γ-rays and the largest masses and annihilation cross sections of neutralino dark matter

Motivated by the interpretation of the recent results on the TeV gamma radiation from the Galactic center, including the new 2004 HESS data, as a by-product of dark matter particles annihilations, we address the question of the largest possible neutralino masses and pair annihilation cross sections in supersymmetric models. Extending the parameter space of minimal models, such as the mSUGRA and...

Gluon Radiation Patterns in Hard Scattering Events∗

The radiation pattern of relatively soft gluons in hard scattering events is sensitive to the underlying color structure. As an example I consider heavy Higgs production via weak boson fusion at the LHC. A minijet veto, which makes use of the different patterns for signal and backgrounds, provides an effective Higgs

Gamma-Rays from Positron Annihilation

SPI on INTEGRAL has provided spectra and a map of the sky in the emission from annihilations of positrons in the interstellar medium of our Galaxy. From high-resolution spectra we learned that a warm, partially-ionized medium is the site where the observed gamma-rays originate. The gamma-ray emission map shows a major puzzle for broader astrophysics topics, as it is dominated by a bright and ex...