Gamma-Ray Astronomy

Diffuseγ-ray background and primordial black hole constraints on the spectral index of density fluctuations

“…The upper limit of Ω BH in PBHs with masses about 5 × 10 14 g was also calculated from the PBH γ-ray emission [8,9]. There exists a homogeneous and isotropic γ-ray background in the universe whose origin is known to be extragalactic [17,18]. Earlier authors postulated a contribution to the DGB from the PBH γ-ray emission [5,8,9].…”

Search for Light Flashes from a Gamma Ray Burst Source

“…A spectral feature at -420 keV in the initial sharp spike (but not present in the subsequent oscillations) is interpreted as gravitationally red-shifted annihilation radiation, implying an origin on the surface of a neutron star. For further details on this event see Cline (1980) and Ramaty and Lingenfelter (1982). As discussed by these authors, some of the features of this event which are not found in others, especially the energy output implied by its assumed distance, make it appear that this event does not belong to the same class as other gamma ray bursts.…”

“…The sources of these bursts remain unidentified and the mechanism(s) responsible for the production of the gamma rays remain(s) in the realm of conjecture. (For a review see Ramaty and Lingenfelter 1982).…”

Detecção de "upward-going" múons no experimento LVD

“…A primeira medida de uma fonte de raios X celeste foi em 1962, registrando sinais de Escorpião X-1 [42] . Seguindo além no espectro, temos a astronomia gama iniciada (1967) experimentalmente com o satélite Vela [43] , que acidentalmente descobriu os bursts de raios gama. Hoje em dia, se realizam vários outros experimentos de astronomia gama, inclusive a procura de fontes pontuais de raios gamas de altíssima energia.…”