Exploring the Dark Age: Star and Galaxy formation in the Early Universe

TL;DR

This paper investigates the processes and diagnostics of star and galaxy formation during the universe's Dark Age, focusing on thermodynamics, molecular cooling, and emission lines to understand early cosmic evolution.

Contribution

It offers a theoretical framework linking emission line diagnostics to the physical conditions of early galaxies and the IGM during the Dark Age.

Findings

Lyα scattering profiles as indicators of early galaxy properties

[C II] emission as a tracer of metallicity and star formation

Simulations elucidate the transition from darkness to illumination in the universe

Abstract

The Cosmic Dark Ages mark a pivotal era of the universe's evolution, transitioning from a neutral, opaque medium to the emergence of the first stars and galaxies that initiated cosmic reionization. This study examines the thermodynamics of the intergalactic medium (IGM), molecular hydrogen cooling, and gravitational collapse that led to structure formation. Key emission lines, such as Lyman-alpha (Ly$\alpha $) and [C II] 158 $\mu m$, are analyzed as tracers of star formation, metallicity, and IGM conditions. Simulations highlight Ly$\alpha $ scattering profiles and [C II] emission as critical diagnostics of early galaxy evolution. The findings provide a theoretical framework to interpret high-redshift observations, advancing our understanding of the universe's transition from darkness to illumination.