Constraining the state of the intergalactic medium during the Epoch of Reionization using MWA 21-cm signal observations

Raghunath Ghara*, Sambit K. Giri, Benedetta Ciardi, Garrelt Mellema, Saleem Zaroubi

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

15 Citaten (Scopus)
19 Downloads (Pure)

Samenvatting

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.
Originele taal-2English
Pagina's (van-tot)4551-4562
Aantal pagina's12
TijdschriftMonthly Notices of the Royal Astronomical Society
Volume503
DOI's
StatusPublished - 17-mei-2021

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