Nature and distribution of dark matter: 1. Milky way and dwarf spheroids

Abstract

We argue that observations on Milky Way and dwarf spheroidals imply existence of individual haloes around dwarf spheroidals. If neutrions (or any other 'hot' particle) provide the dark matter then we show that: (i) Embedding of visible matter inside large (few Mpc) dark matter haloes of about 10 kpc radius around them, and have an (M/L) radio of about 100 kpc in radius. if 'cold' dark matter makes up the haloes, then no significant constraints are obtained. We discuss briefly the effect of these constraints on larger scales.