An Observational Perspective of the IMF: Progress and Challenges

TL;DR

This paper reviews recent observational studies of the stellar initial mass function (IMF), highlighting its apparent invariance across many environments and potential variations under extreme conditions, and discusses ongoing debates about its origin and universality.

Contribution

It provides a comprehensive observational overview of the IMF across different environments, emphasizing its invariance and possible variations, and discusses the challenges in understanding its origin.

Findings

IMF is surprisingly invariant across many environments

Potential IMF variations occur in extreme conditions

Debates continue on the IMF's origin and universality

Abstract

The stellar initial mass function (IMF) is a fundamental astrophysical quantity that impacts a wide range of astrophysical problems from heavy element distribution to galactic evolution to planetary system formation. However, the origin and universality of the IMF are hotly debated both observationally and theoretically. I review recent observations of the IMF across a variety of environments. These suggest the IMF is surprisingly invariant between star-forming regions, star clusters, and spiral galaxies but that it may also vary under extreme conditions, including within the Galactic center and early type galaxies.