2021/03/12 by Raghunath Ghara, Sambit K. Giri, Benedetta Ciardi +3
Engineering · Physics and Astronomy · #Antenna Design and Optimization #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Dark Ages #Epoch (astronomy) #Galaxy #Intergalactic medium #Intergalactic travel #Physics #Radio Astronomy Observations and Technology #Redshift #Reionization #SIGNAL (programming language) #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stab776
13 Pages, 6 Figures, 5 Tables, Accepted for publication in MNRAS
arxiv created 2021/03/12 · openalex publication_date 2021/03/15 · arxiv updated 2021/03/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT The Murchison Widefield Array (MWA) team has derived new upper limits on the spherically averaged power spectrum of the 21-cm signal at six redshifts in the range z ≈ 6.5–8.7. We use these upper limits and a Bayesian inference framework to derive constraints on the ionization and thermal state of the intergalactic medium (IGM) as well as on the strength of a possible additional radio background. We do not find any constraints on the state of the IGM for z ≳ 7.8 if no additional radio background is present. In the presence of such a radio background, the 95 per cent credible intervals of the disfavoured models at redshift ≳ 6.5 correspond to an IGM with a volume-averaged fraction of ionized regions below 0.6 and an average gas temperature ≲ 103 K. In these models, the heated regions are characterized by a temperature larger than that of the radio background, and by a distribution with characteristic size \lesssim 10 h-1 Mpc and a full width at half maximum (FWHM) of \lesssim 30 h-1 Mpc. Within the same credible interval limits, we exclude an additional radio background of at least 0.008 \rm per cent of the CMB at 1.42 GHz.