Nate Bastian (Liverpool John Moores University)

Searching for Variations in the Initial Mass Function of Stars -- Nate Bastian Colloquium

Abstract

Few topics in astronomy initiate such vigorous discussion as whether or not the initial mass function (IMF) of stars is universal, or instead sensitive to the initial conditions of star formation. The distinction is of critical importance: the IMF influences most of the observable properties of stellar populations and galaxies, and detecting variations in the IMF could provide deep insights into the process by which stars form. In this talk, I will review the evidence for and against a varying IMF, concentrating on "extreme" environments, from massive star clusters to high redshift starburst galaxies. Despite indications of "non-standard" IMFs in specific local and extragalactic environments (which clearly warrant further study), there is currently no clear evidence that the IMF varies strongly and systematically after the first few generations of stars. Finally, I will discuss the recent indications that the IMF may be "bottom heavy" in massive early type galaxies