2020/03/31 by Atrideb Chatterjee, Pratika Dayal, Tirthankar Roy Choudhury +1 · 28 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Physics #Population #Quasar #Radio Astronomy Observations and Technology #Redshift #Star formation #Stars #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1093/mnras/staa1609
published in Monthly Notices of the Royal Astronomical Society 496(2), 1445-1452 (Oxford University Press) · accepted to MNRAS
openalex created_date 2020/03/23 · openalex publication_date 2020/06/06 · arxiv created 2020/06/09 · arxiv updated 2020/06/11 · openalex updated_date 2026/08/05
ABSTRACT We aim to provide here the first data-constrained estimate of the metal-free (Population III; Pop III) star formation rate density ρ *III required at high redshifts (z \lower.5ex\hbox \buildrel\gt \over ∼ 16) in order to reproduce both the amplitude and the redshift of the EDGES 21-cm global signal. Our model accounts for the Ly α, radio, and X-ray backgrounds from both Pop III and metal-enriched Population II (Pop II) stars. For the latter, we use the star formation rate density estimates (and the Ly α background) from the Delphi semi-analytic model that has been shown to reproduce all key observables for galaxies at z \lower.5ex\hbox \buildrel\gt \over ∼ 5; the radio and X-ray backgrounds are fixed using low-z values. The constraints on the free parameters characterizing the properties of the Pop III stars are obtained using a Markov Chain Monte Carlo analysis. Our results yield a ρ *III that while increasing from z ∼ 21 to 16 thereafter shows a sharp decline which is in excellent agreement with the results found by Valiante et al. to simulate the growth of z ∼ 6–7 quasars and their host galaxies, suggesting that the bulk of Pop III star formation occurs in the rarest and most massive metal-poor haloes at z ≲ 20. This allows Pop III stars to produce a rapidly growing Ly α background between z ∼ 21 and 15. Further, Pop III stars are required to provide a radio background that is about 3–4 orders of magnitude higher than that provided by Pop II stars although Pop II stars dominate the X-ray background.