Stellar population synthesis diagnostics

Padova Astronomical Observatoy, Vicolo dell'Osservatorio 5, I-35122 Padua, Italy

Received: 4 November 1997
Accepted: 27 March 1998

Abstract

A quantitative method is presented to compare observed and synthetic colour-magnitude diagrams (CMDs). The method is based on a merit function for a point in the observed CMD, which has a corresponding point in the simulated CMD within of the error ellipse. The merit function is then combined with the Poisson merit function of the points for which no corresponding point was found within the error ellipse boundary. 
Monte-Carlo simulations are presented to demonstrate the diagnostics obtained from the combined (, Poisson) merit function through variation of different parameters in the stellar population synthesis tool. The simulations indicate that the merit function can potentially be used to reveal information about the initial mass function. Information about the star formation history of single stellar aggregates, such as open or globular clusters and possibly dwarf galaxies with a dominating stellar population, might not be reliable if one is dealing with a relatively small age range.