Towards a fully consistent Milky Way disc model - III. Constraining the initial mass function

Abstract

We use our vertical Milky Way disc model together with Galaxia to create mock observations of stellar samples in the solar neighbourhood. We compare these to the corresponding volume complete observational samples of dereddened and binary accounted data from Hipparcos and the Catalogue of Nearby Stars. Sampling the likelihood in the parameter space we determine a new fiducial initial mass function (IMF) considering constraints from dwarf and giant stars. The resulting IMF observationally backed in the range from 0.5 to 10 M_⊙ is a two-slope broken power law with -1.49 ± 0.08 for the low-mass slope, a break at 1.39 ± 0.05 M_⊙ and a high-mass slope of -3.02 ± 0.06. The Besançon group also converging to a similar IMF even though their observational sample being quite different to ours shows that the forward modelling technique is a powerful diagnostic to test theoretical concepts like the local field star IMF.