On the origin of the initial mass function

Séminaire IPAG de Patrick Hennebelle (LERMA Paris), jeudi 10 février 2011 à 11h00, IPAG seminar room

Star formation is one of the important problems of the modern astrophysics. Amongst many questions, understanding the initial mass function of stars (IMF), that is how the number of stars vary with mass, is tremendously important and along the years, several theories have been proposed to ex- plain the IMF. More recently, numerical simulations of supersonic turbulence including self-gravity have obtained IMF which resemble the observed one. However, understanding what is exactly happening in these simulations is a challenge in iself. In the talk, I will first review the various theories, which have been proposed. Then, I will present an analytical theory, inspired from the approach used in cosmology to predict the halo of dark matter mass spectrum, which uses the statistical properties of the supersonic turbulence inferred from numerical simulations. The theory predicts an IMF, which seems to be compatible with the observations and the simulations so far. Finally, I will discuss the difficulties that all theories are facing and review some of the solutions, which have been put forward.