Related papers: H.E.S.S. observations of galaxy clusters
We hypothesize that cosmic string loops are the seeds about which globular clusters accrete. Fixing the cosmic string tension by demanding that the peak in the distribution of masses of objects accreting onto string loops agrees with the…
Disturbed spiral galaxies with high rates of star formation pervaded clusters of galaxies just a few billion years ago, but nearby clusters exclude spirals in favor of ellipticals. ``Galaxy harassment" (frequent high speed galaxy…
This paper given at the meeting on "Mapping, Measuring and Modelling the Universe" presents three topics: 1) the study of the clusters and groups of galaxies found serendipitously in the North Ecliptic Pole (NEP) region of the ROSAT all-sky…
Galaxy clusters have the potential to accelerate cosmic rays (CRs) to ultra-high energies via accretion shocks or embedded CR acceleration sites. CRs with energies below the Hillas condition will be confined within the cluster and will…
Galaxy clusters form at the highest density nodes of the cosmic web. The clustering of massive halos is enhanced relative to the general mass distribution and matter beyond the virial region is strongly correlated to the halo mass (halo…
High-spectral resolution observations of clusters of galaxies are a powerful tool to understand the physical processes taking place in these massive objects. Their hot multi-million-degree X-ray emitting cluster atmospheres, containing most…
The Westerlund 1 (Wd 1) is the most massive known young star cluster in the Galaxy, and an extended $\gamma$-ray source HESS J1646-458 surrounding it has been detected up to 80 TeV in the very high energy, implying that cosmic rays (CRs)…
The H.E.S.S. experiment is an array of four imaging Cherenkov telescopes located in the Khomas Highlands of Namibia. It has been operating in its full configuration since December 2003 and detects very-high-energy (VHE) gamma rays ranging…
Ultra-high energy cosmic rays (UHECRs) are the highest energy messengers of the present universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed…
One of the most prominent features of galaxy clusters is the presence of a dominant population of massive ellipticals in their cores. Stellar archaeology suggests that these gigantic beasts assembled most of their stars in the early…
The clustering of ultrahigh energy (>10^{20} eV) cosmic rays (UHECR) suggests that they might be emitted by compact sources. Statistical analysis (Dubovsky et al., 2000) estimated the source density. We extend their analysis to give also…
The most massive galaxies in the present-day Universe are found to lie in the centres of rich clusters. They have old, coeval stellar populations suggesting that the bulk of their stars must have formed at early epochs in spectacular…
Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy…
Clusters of galaxies are self-gravitating systems of mass ~10^14-10^15 Msun. They consist of dark matter (~80 %), hot diffuse intracluster plasma (< 20 %) and a small fraction of stars, dust, and cold gas, mostly locked in galaxies. In most…
A model is proposed for the origin of cosmic rays (CRs) from ~10^14 eV to the highest energies, >10^20 eV. Gamma-Ray Bursts (GRBs) are assumed to inject CR protons and ions into the interstellar medium of star-forming galaxies--including…
Clusters of galaxies need to be investigated using complementary approaches combining all currently available observational techniques (X-ray, gravitational lensing, dynamics, SZ) on homogeneous samples if one wants to understand their…
The identification of major contributors to the locally observed fluxes of Cosmic Rays (CRs) is a prime objective towards the resolution of the long-standing enigma of CRs. We report on a compelling similarity of the energy and radial…
The cluster of ultra-high-energy cosmic rays observed by the AGASA, HiRes and Yakutsk experiments is studied with respect to possible deflections of particles in regular magnetic fields. Best-fit positions of a potential source of these…
The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Energetic particles in our own galaxy, galactic cosmic rays (GCRs),…
The nature of cosmic rays (CRs) and cosmic ray transport in galaxy clusters is probed by a number of observations. Radio observations reveal the synchrotron radiation of cosmic ray electrons (CRe) spiraling around cluster magnetic fields.…