Colloquium: Population III stars: the window to cosmic dawn

© Piyush Sharda

Population III stars were the first stars that formed in the Universe, a mere 200 - 300 million years after the Big Bang. These stars produced the first supernovae and black holes, enriched the interstellar medium (ISM) with metals, were the building blocks of the first galaxies, and significantly contributed to cosmic reionization. However, no Population III stars have ever been observed. Compared to star formation and feedback in metal-rich environments today, the lack of direct observations at low metallicities has posed a significant challenge for understanding the physics behind their formation and evolution. In this talk, I will introduce POPSICLE, a new framework for high resolution simulations that caters to star formation and feedback in low metallicity environments reminiscent of redshift > 10 galaxies as well as metal-poor dwarf galaxies at redshift zero. I will describe how incorporating the full spectrum of ISM physics coupled to stellar evolution is crucial to constrain the stellar initial mass function (IMF) and feedback in such environments. I will particularly focus on Population III stars, and discuss the interplay between different physical mechanisms that sets their masses, and their role in feedback and black hole growth in the early Universe. I will conclude by showcasing the capability of GPU-accelerated simulations to revolutionize our understanding of the astrophysics of cosmic dawn, and bring theory at par with state of the art observations from JWST.