Related papers: Unveiling cosmic X-ray/gamma-ray sources from thei…
X-ray observations of clusters provide key information on the dark matter, on the formation of structures in the Universe, and can be used to constrain the cosmological parameters. I review our current knowledge, with emphasis on recent XMM…
Galactic cosmic rays are believed to be accelerated at supernova remnant shocks. Gamma-ray observations of both supernova remnants and associated molecular clouds have been used in several occasions to test (so far quite successfully) this…
The features and make up of the population of X-ray sources in Galactic star clusters reflect the properties of the underlying stellar environment. Cluster age, mass, stellar encounter rate, binary frequency, metallicity, and maybe other…
During the last two decades Gamma-Ray Astronomy has emerged as a powerful tool to study cosmic ray physics. In fact, photons are not deviated by galactic or extragalactic magnetic fields so their directions bring the information of the…
The origin of the highest energy cosmic rays represents one of the most conspicuous enigmas of modern astrophysics, in spite of gigantic experimental efforts in the past fifty years, and of active theoretical research. The past decade has…
This article reviews the present status of high energy gamma-ray astronomy at energies above 30 MeV. Observations in the past decade using both space- and ground-based experiments have been primarily responsible for giving a tremendous…
Gamma-ray bursts and ultra-high-energy cosmic rays provide an important testing ground for fundamental physics. A simple-minded analysis of some gamma-ray bursts would lead to a huge estimate of the overall energy emitted, and this…
Recently, two nearby prominent starburst galaxies, M82 and NGC253, have been detected as point-like sources with gamma-ray telescopes at TeV energies [1] [2]. It has been claimed that these detections show that the cosmic ray intensity in…
In the standard internal shock model, the observed X and gamma-ray radiation is assumed to be produced by synchrotron emission. I will show that there are serious problems with this interpretation, calling for other radiation mechanisms,…
Deviations from isotropy have been a key tool to identify the origin and the primary type of cosmic rays at low energies. We suggest that the Compton-Getting effect can play a similar role at ultra-high energies: If at these energies the…
Modern X-ray observatories yield unique insight into the astrophysical time domain. Each X-ray photon can be assigned an arrival time, an energy and a sky position, yielding sensitive, energy-dependent light curves and enabling…
The recent simultaneous detection of optical, X-ray and gamma-ray photons from GRB990123 during the burst provides the first broadband multi-wavelength characterization of the burst spectrum and evolution. Here we show that a direct…
Time-resolved ultrafast x-ray scattering is an emerging approach to probe the temporally evolving electronic charge distribution in real-space and in real-time. In this contribution, time-resolved ultrafast x-ray scattering from an…
Interactions of grazing incidence, ultra high energy cosmic rays with the earth's atmosphere may provide a new method of studying energetic cosmic rays with gamma-ray satellites. It is found that these cosmic ray interactions may produce…
In cosmic ray physics extensive progress has been made in recent years, both concerning theory and observation. The vast details in direct, indirect and secondary detections on the one hand provide the basis for a detailed modeling of the…
Gamma-Ray Bursts (GRBs) are the brightest sources in the universe, emit mostly in the hard X-ray energy band and have been detected at redshifts up to ~8.1. Thus, they are in principle very powerful probes for cosmology. I shortly review…
The origin of the highest energy cosmic rays is still unknown. The discovery of their sources will reveal the workings of the most energetic astrophysical accelerators in the universe. Current observations show a spectrum consistent with an…
A considerable fraction of incident high-energy photons from astrophysical transients such as Gamma-Ray Bursts (GRBs) is Compton scattered by the Earth's atmosphere. These photons, sometimes referred to as the "reflection component",…
Over the last two decades, the discovery of exoplanets has fundamentally changed our perception of the universe and humanity's place within it. Recent work indicates that a solar system's X-ray and high energy particle environment is of…
Supplementary Information Content: 1. Sample preparation; 2. Background subtraction of Shubnikov-de Haas (SdH) oscillations; 3. The effect of density inhomogeneity on the quantum scattering time tau_q; 4. Determine the concentration of…