Astrophysical constraints on a possible neutrino ball at the Galactic Center F. De Paolis, G. Ingrosso, A. A. Nucita, D. Orlando, S. Capozziello and G. Iovane A&A, 376 3 (2001) 853-860 Published online: 15 September 2001 DOI: 10.1051/0004-6361:20010929