Speaker
Description
The formation of the first stars marks a watershed moment in the history of our universe. As the first luminous structures, these stars (also known as Population III, or Pop III stars) seed the first galaxies and begin the process of reionization, but are challenging to observe. We construct an analytic model to self-consistently trace the formation of Pop III stars inside minihalos in the presence of the fluctuating ultraviolet background, relic dark matter-baryon relative velocities from the early universe, and an X-ray background, which largely work to suppress cooling of gas and delay the formation of this first generation of stars. We demonstrate the utility of this framework in a semi-analytic model for early star formation that follows the transition between Pop III and Pop II star formation inside these halos and computes the radiation backgrounds that will determine the 21-cm spin temperature. Using our new prescription for the criteria allowing Pop III star formation, we follow a population of dark matter halos from z = 50 through z = 6 and examine the global star formation history, finding that each process defines its own key epoch: (i) the stream velocity dominates at the highest redshifts (z>30), (ii) the UV background sets the tone at intermediate times (30<z<15), and (iii) X-rays control the end of Pop III star formation at the latest times (z<15). In all of our models, Pop III stars continue to form down to z ∼ 7 − 10. In this talk, I will present our semi-analytic model and detail how it can be leveraged to predict key observables—such as for transient surveys and 21-cm and line intensity mapping experiments—that can help to constrain the properties of this first generation of stars.
