The recent observations of microlensing events in the LMC by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in the form of Massive Halo Objects (MHO) of about 0.1Msun_. Here, we argue that the galactic halo is mainly baryonic and that besides MHO also H_2_ molecular clouds may significantly contribute to it. We propose a scenario in which dark clusters of MHO and/or H_2_ molecular clouds form in the halo at galactocentric distances larger than ~10-20kpc, since there we expect less collisions among proto globular cluster clouds and a smaller UV radiation flux. Cosmic ray protons may induce a significant γ-ray flux in H_2_ molecular clouds. Our calculation gives an upper bound to this flux which is below present detectability.
A scenario for a baryonic dark halo
DE PAOLIS, Francesco;INGROSSO, Gabriele;
1995-01-01
Abstract
The recent observations of microlensing events in the LMC by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in the form of Massive Halo Objects (MHO) of about 0.1Msun_. Here, we argue that the galactic halo is mainly baryonic and that besides MHO also H_2_ molecular clouds may significantly contribute to it. We propose a scenario in which dark clusters of MHO and/or H_2_ molecular clouds form in the halo at galactocentric distances larger than ~10-20kpc, since there we expect less collisions among proto globular cluster clouds and a smaller UV radiation flux. Cosmic ray protons may induce a significant γ-ray flux in H_2_ molecular clouds. Our calculation gives an upper bound to this flux which is below present detectability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
