PAMELA and ATIC recently reported excesses in e± cosmic rays. Since the interpretation in terms of DM annihilations was found to be not easily compatible with constraints from photon observations, we consider the DM decay hypothesis and find that it can explain the e± excesses compatibly with all constraints, and can be tested by dedicated HESS observations of the Galactic Ridge. ATIC data indi...

a Department of Physics and Astronomy, Lehman College, City University of New York, NY 10468, USA b Department of Physics, Graduate Center, City University of New York, NY 10016, USA c Department of Astrophysics, American Museum of Natural History, NY 10024, USA d LPTHE, UMR CNRS 7589, Sorbonne Universités, UPMC Paris 6, 75005 Paris, France e Albert Einstein Center, Institute for Theoretical Ph...

Recent results from experiments like PAMELA have pointed to excesses of e± in cosmic rays. If interpreted in terms of Dark Matter annihilations, they imply the existence of an abundant population of e± in the galactic halo at large. We consider the high energy gamma ray fluxes produced by Inverse Compton scattering of interstellar photons on such e±, and compare them with the available data fro...

Observations with the Extreme Ultraviolet Explorer satellite are purported to show extreme ultraviolet (EUV) and soft X-ray excesses in several clusters of galaxies (Bonamente, Lieu & Mittaz 2001). If interpreted as thermal emission, this would imply the presence of warm (T ∼ 10 K) gas in these clusters with a mass comparable to that of gas at coronal temperatures. If true, this would have prof...

The cosmic-ray excess observed by PAMELA in the positron fraction and by FERMI and HESS in e− + e can be interpreted in terms of DM annihilations or decays into leptonic final states. Final states into τ ’s or 4μ give the best fit to the excess. However, in the annihilation scenario, they are incompatible with photon and neutrino constraints, unless DM has a quasi-constant density profile. Fina...