Dark Matter in NGC 4472

I attempt to constrain the total mass distribution of the well- observed giant elliptical galaxy NGC 4472 by constructing simultaneous equilibrium models for the gas and stars using all available relevant optical and X-ray data. The value of <ɛ>, the emission-weighted average value of kT, derived from the Ginga spectrum- <ɛ> = 1.9+/-0.2 keV (Awaki et al.)-can be reproduced only in hydrostatic models where nonluminous matter comprises at least 90% of the total mass. However, in general, these mass models are not consistent with observed projected stellar and globular cluster velocity dispersions at moderate radii (0.5'-4.0'). Mass models with hydrostatic gas distributions that have <ɛ> = 1.5 keV are marginally consistent with the stellar velocity dispersion data; and I discuss how contributions to the X-ray spectrum from additional high-temperature components such as supernova bubbles, X-ray binaries, and encroaching intracluster gas may cause simple one-component analysis of X-ray spectra to systematically overestimate the true hydrostatic gas temperature. These effects, however, cannot be important enough to reduce the required amount of dark matter below 70% of the total mass; models without dark matter have <ɛ> < 0.8 keV. If the true value of <ɛ> is 1.5 keV or greater, the range of dark matter distributions consistent with both X-ray and optical spectra is very small, essentially consisting of a line in the halo scale length-total mass plane, and the inferred minimum mass-to-light ratio is 40h_50_ in solar units where h_50_ is the Hubble constant in units of 50 km s^-1^ Mpc^-1^.