相关论文: Anisotropy studies around the galactic center
Cosmic rays are atomic nuclei arriving from outer space that reach the highest energies observed in nature. Clues to their origin come from studying the distribution of their arrival directions. Using $3 \times 10^4$ cosmic rays above $8…
If clustering of the arrival directions of ultra high energy cosmic rays is discovered, this would provide important information about their origin, composition, and the galactic and extragalactic magnetic fields. We present here the…
The Pierre Auger Observatory has by now achieved an exposure of order $10^5~{\rm km}^2$ sr yr, exploring about 85% of the sky. In this talk, I will review some of the recent results, including the detailed measurements of the features in…
The region near the Galactic center may have experienced recurrent episodes of injection of energy in excess of $\sim$ 10$^{55}$ ergs due to repeated starbursts involving more than $\sim$ 10$^4$ supernovae. This hypothesis can be tested by…
We study the propagation of ultra-high-energy cosmic rays (UHECR) in the Galaxy, concentrating on the energy range below the ankle in the spectrum at 4 EeV. A Monte-Carlo method, based on analytical solutions to the time-dependent diffusion…
We have performed the detailed numerical simulations on the propagation of the UHE protons in the energy range $E=(10^{19.5} - 10^{22.0}$) eV in the relatively strong extra-galactic magnetic field with strength $B= (10, 100)$ nG within…
Over ten years ago, Fermi observed an excess of GeV gamma rays from the Galactic Center whose origin is still under debate. One explanation for this excess involves annihilating dark matter; another requires an unresolved population of…
We present results of numerical simulations of the propagation of ultra high energy cosmic rays (UHECRs) over cosmological distances, aimed at quantifying the statistical significance of the highest energy data on the spectrum and small…
AIMS. To check whether the polar angle distribution of QSOs around nearby spiral galaxies is isotropic or not. METHODS. A statistical analysis of the polar angle distribution of large samples of QSOs from the SDSS survey and Monte Carlo…
Sgr A East is a supernova remnant located within few parsecs from the Galactic Centre (GC). There are good reasons to believe that this object is the source of the gamma-ray excess detected by HESS in the direction of the GC meaning that…
After a century of observations, we still do not know the origin of cosmic rays. I will review the current state of cosmic ray observations at the highest energies, and their implications for proposed acceleration models and secondary…
I describe some of the results on ultrahigh-energy cosmic rays that have been obtained with the Pierre Auger Observatory. These include measurements of the spectrum, composition and anisotropies. Possible astrophysical scenarios that…
Several explanations for the existence of Ultra High Energy Cosmic Rays (UHECR) invoke the idea that they originate from the decay of massive particles created in the reheating following inflation. It has been suggested that the decay…
We propose that neutron emission from Cen A dominates the cosmic ray sky at the high end of the spectrum. Neutrons that are able to decay generate proton diffusion fronts, whereas those that survive decay produce a spike in the direction of…
Several explanations for the existence of Ultra High Energy Cosmic Rays invoke the idea that they originate from the decay of massive particles created in the reheating following inflation. It has been suggested that the decay products can…
A consequence of Liouville's theorem indicates that the recently observed large scale anisotropy in the arrival direction of Ultra-High-Energy Cosmic Rays (UHECRs) cannot be produced by the Galactic magnetic field, thus this anisotropy…
The Pierre Auger Observatory is the world's largest operating detection system for the observation of ultra high energy cosmic rays (UHECRs). The detector allows detailed measurements of their energy spectrum, mass composition and arrival…
Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations extend the energy range in the electron flux measurement up to unexplored energies in the hundred GeVs range confirming the bump starting at about 10GeV already…
Cosmic rays begin to reveal their secrets at energies above 5 EeV. Beyond this characteristic energy, known as the spectral "ankle", the arrival-direction data from the Pierre Auger Observatory show anisotropy on large angular scales of…
With the Surface Detector array (SD) of the Pierre Auger Observatory we can detect neutrinos with energy between $10^{17}\,$eV and $10^{20}\,$eV from point-like sources across the sky, from close to the Southern Celestial Pole up to…