Motivated by the recent results from the PAMELA and ATIC, we study the cosmic-ray electron and positron produced by the decay of gravitino dark matter. We calculate the cosmic-ray electron and positron fluxes and discuss implications to the PAMELA and ATIC data. In this paper, we will show that the observed anomalous fluxes by the PAMELA and ATIC can be explained in such a scenario. We will als...

The propagation of cosmic rays through the interstellar medium (ISM) inevitably produces LiBeB nuclei, and the accumulation of these elements over lifetime of galaxy can broadly account for the solar LiBeB abundances. Furthermore, data in old (Population II) stars provides crucial new information: the LiBeB trend versus heavy element abundances traces the Galactic evolution of LiBeB. We summari...

New data from the cosmic ray experiment on the Voyager spacecraft confirms and extends earlier data from a similar experiment on the ISEE-3 spacecraft which indicates the possibility of the decay of certain K-capture isotopes during the interstellar propagation of galactic cosmic rays. These cosmic ray measurements, along with the cross section measurements, indicate that ∼ 25% of the K-capture...

We present radio continuum polarimetry observations of the nearby edge-on galaxy NGC 253 which possesses a very bright radio halo. Using the vertical synchrotron emission profiles and the lifetimes of cosmic-ray electrons, we determined the cosmic-ray bulk speed as 300± 30 km s−1, indicating the presence of a galactic wind in this galaxy. The large-scale magnetic field was decomposed into a tor...

The cosmic X-ray background (XRB) is largely due to accretion onto supermassive black holes integrated over cosmic time. Thus, extragalactic X-ray surveys offer the potential to contribute substantially to our understanding of the physics of Active Galactic Nuclei (AGN) as well as the evolution of the AGN population. Such surveys have dramatically advanced over the past four years, largely due ...

We use the GALPROP model for cosmic-ray propagation to obtain a new estimate of the Galactic component of gamma rays, and show that away from the Galactic plane it gives an accurate prediction of the observed EGRET intensities in the energy range 30 MeV – 50 GeV. On this basis we reevaluate the extragalactic gamma-ray background. We find that for some energies previous work underestimated the G...

[1] We present a re-evaluation of the hypothesis of a coupling between galactic cosmic rays, clouds and climate. We have used two independent estimates of low cloud cover from the International Satellite Cloud Climatology Project, covering 16.5 years of data. The cloud cover data are used in conjunction with estimates of galactic cosmic ray flux and measurements of solar irradiance. It is found...

The cosmic X-ray background (XRB) is largely due to accretion onto supermassive black holes integrated over cosmic time. Thus, extragalactic X-ray surveys offer the potential to contribute substantially to our understanding of the physics of Active Galactic Nuclei (AGN) as well as the evolution of the AGN population. Such surveys have dramatically advanced over the past four years, largely due ...

We study the inverse Compton scattering of solar photons by Galactic cosmic-ray electrons. We show that the γ-ray emission from this process is substantial with the maximum flux in the direction of the Sun; the angular distribution of the emission is broad. This previously-neglected foreground should be taken into account in studies of the diffuse Galactic and extragalactic γ-ray emission. Furt...

[1] We present a quasi-steady two-dimensional (axisymmetric) model of the heliospheric transport of galactic cosmic rays. The model is based on stochastic simulation techniques and includes all the modulation mechanisms that cosmic rays experience in the heliosphere: convection, adiabatic cooling, diffusion, and drifts. A special emphasis is given to the cosmic ray transport in the vicinity of ...