Galaxies and Cosmology Seminar
May
19
2025
May
19
2025
Description
"Let there be light", and There Were Pop. III Stars
Detecting the light from the first generation of metal-free stars (Population III) is a challenging task, even with state-of-the-art observational facilities. In this talk, I will explore three potential avenues for identifying Pop III stars: chemical enrichment of the intergalactic medium (IGM), the 21cm power spectrum, and direct detection in high-redshift galaxies observed by JWST. Using a semi-analytical model of galaxy formation and reionization that incorporates Pop III star formation, we find that signatures of these stars are likely to appear in low-mass systems toward the end of the reionization era (z ≈ 5–6), where chemical enrichment is predominantly driven by Pop III supernovae. Among the available probes, the 21cm power spectrum is the most promising tool, and it is a primary target of current and upcoming radio observatories such as HERA and SKA. In particular, if Pop III stars formed with a top-heavy IMF, their remnants could significantly heat the IGM as early as z > 15. This early heating imprints a distinctive signal on small scales, where the 21cm power spectrum can be enhanced by up to an order of magnitude when Pop III contributions are included. Finally, I will discuss the possibility of directly detecting Pop. III stars with JWST examining the potential Pop. III contribution both in the z>14 bright galaxies and in the low-metallicity z = 6-10 galaxies.
Location
PMA 15.216B and online
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