Related papers: Fermi Pulsars and the Cosmic Ray Knee
The most energetic neutron stars, powered by their rotation, are capable of producing pulsed radiation from the radio up to gamma rays with nearly TeV energies. These pulsars are part of the universe of energetic and powerful particle…
Fermi bubbles are giant gamma-ray structures extended north and south of the Galactic center with characteristic sizes of order of 10 kpc recently discovered by Fermi Large Area Telescope. Good correlation between radio and gamma-ray…
We derive an upper limit to the energy of nuclei accelerated via the Fermi mechanism in any relativistic shockwave, driven by any astrophysical engine. This bound is accessible to current and upcoming ultra-high energy neutrino experiments.…
We measure the emission of energetic electrons from the interaction between ultrashort laser pulses and a solid density plasma in the relativistic regime. We detect an electron beam that only appears with few-cycle pulses (< 10 fs) and…
Cosmic rays and solar energetic particles may be accelerated to relativistic energies by shock waves in astrophysical plasmas. On the Sun, shocks and particle acceleration are often associated with the eruption of magnetized plasmoids,…
In a comprehensive model of Cosmic Rays (CRs) proposed a decade ago, the energies of the spectral "knees" of the various CR species were predicted to be proportional to mass, rather than charge. The model also predicts the knees to occur at…
Nuclear Fermi momentum is a basic property of a nucleus where many nucleons dwell. However, in experiments only the nuclear Fermi momenta of just a few nuclei are measured using quasielastic electron scattering on the nuclear targets so…
The nucleus is one of the most multi-faceted many-body systems in the universe. It exhibits a multitude of responses depending on the way one 'probes' it. With increasing technical advancements of beams at the various accelerators and of…
The energy spectrum of ultra-high energy cosmic rays (UHECR) is usually calculated for sources with identical properties. Assuming that all sources can accelerate UHECR protons to the same extremely high maximal energy E_max > 10^{20} eV…
We analyze the possibility that the cosmic ray knee appears at an energy threshold where the proton-dark matter cross section becomes large due to new TeV physics. It has been shown that such interactions could break the proton and produce…
For more than half a century, nucleons are considered to move continuously in the nuclei. Recent electron-scattering experiments indicate about 20$\sim$25\% nucleons in heavier nuclei are involved in the neutron-proton short-range…
Scenarios in which the knee of the cosmic ray spectrum depends on the particle rigidities usually predict that the cosmic ray composition becomes heavier above the knee and have associated a change in the spectral slope of each individual…
The processes leading to the exceptionally hard radio spectra of pulsar-wind nebulae (PWNe) are not yet understood. Radio photon spectral indices among $29$ PWNe from the literature show an approximately normal, $\alpha=0.2\pm0.2$…
The energies of cosmic rays, fully ionized charged nuclei, extend over a wide range up to 10^20 eV. A particularly interesting energy region spans from 10^14 to 10^18 eV, where the all-particle energy spectrum exhibits two interesting…
The hypothesis that the electron neutrino is a tachyon with |m|=sqrt(-m^2) = 0.5 eV/c^2 is consistent with certain properties of the cosmic ray spectrum, including: the existence of a change in power law (the "knee") at E = 10^15 eV, the…
The main purpose of this work is to find the causes of the break of the cosmic ray spectrum at an energy of 3 PeV, which is called the knee. The solution of the problem is associated with the determination of the nuclear composition of…
Recent results from the PAMELA satellite indicate the presence of a large flux of positrons (relative to electrons) in the cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles in many models are…
Fermi LAT has detected gamma ray emissions from the core of Cen A. More recently, a new component in the gamma ray spectrum from the core has been reported in the energy range of 4 GeV to tens of GeV. We show that the new component and the…
Most pulsars observed by the Fermi LAT have gamma-ray luminosities scaling with spindown power Edot as L_gamma (Edot x 10^33 erg/s)^{1/2}. However, there exist one detection and several upper limits an order of magnitude or more fainter…
The {\it Fermi} Large Area Telescope has recently discovered two giant gamma-ray bubbles which extend north and south of the Galactic center with diameters and heights of the order of $H\sim 10$ kpc. We suggest that the periodic star…