Astronomy and Astrophysics, volume 321, 343-352 (1997/5-1)
M/LB and [Fe/H] of elliptical galaxies and the initial mass function.
ANGELETTI L. and GIANNONE P.
Abstract (from CDS):
The observed trend of mass-to-light ratio M/LB versus elliptical galaxy mass M has been interpreted in various ways by different authors in recent years. We explore in greater detail than previously done the hypothesis that the mentioned trend can be ascribed to a systematic change of the initial mass function (IMF) with M. We use a three-segment power-law IMF with mass exponents x1, x2, and x3 for stellar masses m (in M☉) in the ranges 0.1<m<0.3, 0.3<m<2, and 2<m<100, respectively. The exponent x1 is considered as a free parameter in the range 0/3.5, while x2 and x3 are determined using relations M/LB versus M and [Fe/H] versus M as constraints. We find that x2+3.4x3≃-0.72logM+const., irrespectively of whether the bottom IMF exponent x1 varies from a flat to a very steep behaviour. We single out a number of realistic solutions; for all of them dx3/dlogM=-0.16/-0.35. On the other hand, solutions with x2=const., x3=const., and x1 variable with M are to be excluded, being at variance with the observed [Fe/H]-M relationship. We confirm that a variable single-slope IMF is not a very appealing solution since it requires a minimum stellar mass ml>0.24.
galaxies: elliptical and lenticular - elliptical galaxies: fundamental plane and metallicity