Ivelin Georgiev, "Impact of the Mean Free Path of ionising photons on the observables from the Epoch of Reionisation"

Wednesday 14 Sept 2022, 13:30 → 14:30 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

The Epoch of Reionisation (EoR) was the period of the Universe during which the neutral hydrogen (HI) present in the intergalactic medium (IGM) was ionised by Ultraviolet radiation from sources inside early galaxies. The HI present in the IGM can emit radiation via the 21-cm hyperfine transition, hence the 21-cm signal from the EoR is a direct probe of the process of cosmic reionisation.

We base our study on the analysis of numerical simulations and focus on the largest detectable scales. In this talk, I will discuss how the decomposition of the 21-cm power spectrum into its constituent auto and cross-correlation power spectra can help us understand its evolution and aid in extracting information about the impact of the sources and the density field. I address the significance of the value and implementation of the mean free path (MFP) of ionising photons on the shape of the 21-cm power spectrum. Our findings indicate that the MFP constraint determines the scale that separates the astrophysical and cosmological parts of the power spectrum through the relation k~2/λMFP . The recent claims of very short values for the MFP (e.g. Becker et al. 2021) would imply that this transition could fall well into the range of scales accessible to interferometric experiments. We find that a shorter MFP not only extends the EoR but is consistent with current measurements of the UV background.

Georgiev_2022-Sep-14.mp4