Marco Roncadelli

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The observational evidence for dark matter on progressively larger cosmic scales is reviewed in a rather pedagogical fashion. Although the emphasis is on dark matter in galaxies and in clusters of galaxies, its cosmological evidence as well as its physical nature are also discussed.
Axion-Like Particles (ALPs) are predicted by many extensions of the Standard Model and give rise to characteristic dimming and polarization effects in a light beam travelling in a magnetic field. In this Letter, we demonstrate that photonALP mixing in cosmic magnetic fields produces an observable distortion in the energy spectra of distant gamma-ray sources(More)
We present numerical calculations of the photon-light-pseudoscalar-boson (LPB) production in the recently discovered binary pulsar system J0737-3039. Light pseudoscalar bosons oscillate into photons in the presence of strong magnetic fields. In the context of this binary pulsar system, this phenomenon attenuates the light beam emitted by one of the pulsars,(More)
Recent findings by γ-ray Cherenkov telescopes suggest a higher transparency of the Universe to very-high-energy (VHE) photons than expected from current models of the Extragalactic Background Light. It has been shown that such transparency can be naturally explained by the DARMA scenario, in which the photon mixes with a new, very light, axion-like particle(More)
A recent article from the Pierre Auger Collaboration links the direction of charged cosmic rays to possible extragalactic sites of emission. The correlation of the direction of such particles with the direction of the emitter allows constraining the value of large-scale magnetic fields B. Assuming for B a coherence length λ in the range between 1 Mpc and 10(More)
The WARP programme for dark matter search with a double phase argon detector is presented. In such a detector both excitation and ionization produced by an impinging particle are evaluated by the contemporary measurement of primary scintillation and secondary (proportional) light signal, this latter being produced by extracting and accelerating ionization(More)
A recent article from the Pierre Auger Collaboration links the direction of charged cosmic rays to possible extragalactic sites of emission. The correlation of the direction of such particles with the direction of the emitter allows constraining the value of large-scale magnetic fields B. Assuming for B a coherence length λ in the range between 1 Mpc and 10(More)
Primordial nucleosynthesis as well as anisotropies in the cosmic microwave background radiation imply that the total amount of baryons in the Universe largely exceeds the visible contribution, thereby making a strong case for baryonic dark matter. Moreover, certain recent developments lead to a consistent picture of the dark baryon budget in the present-day(More)
Recent observations of microlensing events in the Large Magellanic Cloud suggest that a sizeable fraction of the galactic halo is in the form of Massive Astrophysical Compact Halo Objects (MACHOs) with mass less than about 0.1M⊙. Here we argue that molecular clouds (mainly of H2) located in the galactic halo can contribute substantially to its total mass.(More)