Massive stars as gravitationally lensed transients -- Insights on the high-mass initial mass function

TL;DR

This paper discusses a new method using transient gravitational lensing of massive stars to probe the stellar initial mass function in distant galaxies, providing insights into star formation beyond the local universe.

Contribution

It introduces a novel approach to measure the IMF in high-redshift galaxies through the detection of lensed transient stars, addressing limitations of traditional methods.

Findings

No evidence for a top-heavy IMF at z ≈ 1.

Method can distinguish IMF variations from star formation history.

Provides a new observational window into distant galaxy star formation.

Abstract

A robust stellar initial mass function (IMF) is crucial in any studies related to star formation. However, the direct measurement of the stellar IMF is confined to the local universe, limited by the resolving power of telescopes. Recently, a new method for accessing the stellar IMF beyond the local universe has been developed. The observed detection rate of transient lensed stars -- individual, massive, thus luminous stars in strongly lensed galaxies that are temporarily detectable upon stellar microlensing -- can serve as a probe to break the IMF-star formation history degeneracy in studies utilizing spectral energy distribution fitting, hence providing a window to look at the IMF at a subsample of gravitationally lensed galaxies. In this proceeding, I summarize the contributed talk given at IAUS402 entitled the same as this contribution and highlight some key results, which currently show no evidence for a top-heavy IMF in $z \approx 1$ galaxies.