Related papers: Fat cosmic ray tracks in charge-coupled devices
A gamma-ray excess over background has been claimed in the inner regions of the Galaxy, triggering some excitement about the possibility that the gamma rays originate from the annihilation of dark matter particles. We point out that the…
Cosmic rays are often modeled as charged particles. This allows their non-ballistic propagation in magnetized structures to be captured. In certain situations, a neutral cosmic ray component can arise. For example, cosmic ray neutrons are…
The origin of the bulk of cosmic rays (CRs) observed at Earth is the topic of a century long investigation, paved with successes and failures. From the energetic point of view, supernova remnants (SNRs) remain the most plausible sources of…
Ultrahigh energy cosmic rays are the most energetic of any subatomic particles ever observed in nature. The quest for their mysterious origin is currently a major scientific challenge. Here we explore the possibility that these particles…
It has been speculated that the recently detected ultra-high energy cosmic rays may originate from the decays of relic particles with mass of order $10^{12}$ GeV clustered in the halo of our Galaxy. This hypothesis can be tested through…
Trace charge imbalances can explain puzzling cosmological observations such as the large `missing' fraction of electrons in cosmic rays and their contrast to the charge-neutral solar wind, the extreme energy sources that sustain pulsars,…
Assuming that cosmic rays entering the Earth's atmosphere contain a small admixture of nuggets of strange quark matter in form of strangelets one can explain a number of apparently "strange" effects observed in different cosmic rays…
Possible existence of extragalactic ultra-high energy cosmic ray sources giving a very small particle flux on the Earth is considered. Accretion discs around supermassive black holes where particles are accelerated in electric fields are…
The understanding of the nature of ultra-high-energy cosmic rays is one of the most intriguing open questions for current and future observatories. These particles are expected to be accelerated in extragalactic sources. Because of their…
Dark matter particles could be the major component of the haloes of galaxies. Their mutual annihilations or decays would produce an indirect signature under the form of high-energy cosmic-rays. The focus of this presentation is on…
Cosmic-ray interactions with interstellar gas and photons produce diffuse gamma-ray emission. In this talk we will review the current understanding of this diffuse emission and its relationship to the problem of the origin of cosmic rays.…
We study the possibility that an extended cosmic-ray leptonic and/or hadronic halo is at the origin of the large-scale gamma-ray emission detected from the Andromeda Galaxy (M31). We consider a broad ensemble of non-homogeneous diffusion…
Cosmic ray particles with energies in excess of 10**(20) eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This report gives a…
Origin of ultra high energy cosmic rays is an unsolved problem. Several proposals such as Z-burst, decay of super massive matter, susy particles as a primary, neutrino as a primary in extra dimension models exist in the literature which try…
The physical origin of the X-ray emission in powerful quasar jets has been a long-standing mystery. Though these jets start out on the sub-pc scale as highly relativistic flows, we do not have any direct measurement of their speeds on the…
We review the basic ideas on the origin of cosmic rays with energy in excess of $\sim 10^{19}$ eV, in the light of the most recent observational findings. The limited statistics of events detected by the two largest experiments currently…
The origin of Galactic cosmic rays (with energies up to 10^15 eV) remains unclear, though it is widely believed that they originate in the shock waves of expanding supernova remnants. Currently the best way to investigate their acceleration…
The abundances of neon isotopes in the galactic cosmic rays (GCRs) are reported using data from the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE). We compare our ACE-CRIS data for neon and refractory…
A critical review of the standard paradigm for the origin of Galactic cosmic rays is presented. Recent measurements of local and far-away cosmic rays reveal unexpected behaviours, which challenge the commonly accepted scenario. These recent…
It is believed that the observed diffuse gamma ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular…