Mass Models of Three Southern Late-Type Dwarf Spirals [chapter]

C. Carignan
1985 The Milky Way Galaxy  
Although rotation-curve studies of spiral galaxies have unambigu ously established the presence of dark matter, and theoretical studies have shown that its location is likely to be in a separate spheroidal halo component (Binney, 1978; Tubbs and Sanders, 1979 ; Monet, Richstone and Schechter, 1981), very little is known about its spatial dis tribution and its nature. Recently, Faber and Lin (Faber and Lin, 1983; Lin and Faber, 1983) have shown that, if one can get a rough idea of fundamental
more » ... a of fundamental parameters like the halo scale length and the halo-to-disk ratio, it is also possible to put strong constraints on the nature of non-luminous matter. One way to determine its spatial distribution, is to try to probe the gravitational potential as far out as possible through rotation velocities, and then, by using mass models, to subtract the contribution of the luminous matter to the potential. Assuming a constant M/L for the luminous disk, this can be done since the light distribution can then be transformed directly into a mass distribution. However, high-sensitivity HI observations are necessary, since optical velocities rarely extend past the disk-dominated region (e.g. see Kalnajs, 1983 for NGC 7217 and NGC 4378). One-component models (Kalnajs , 1983) using Carignan's photometry (1983) and two-component disk-halo models (exponential disk and iso-95 H. van Woerden et al. (eds.), The Milky Way Galaxy, 95-96. © 1985 by the IAV. available at https://doi.
doi:10.1007/978-94-009-5291-1_8 fatcat:fuj4dktwtjaubmcveytzbcyboq