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Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1 (2025)
Journal Article
Mertens, F. G., Mevius, M., Koopmans, L. V. . E., Offringa, A. R., Zaroubi, S., Acharya, A., Brackenhoff, S. A., Ceccotti, E., Chapman, E., Chege, K., Ciardi, B., Ghara, R., Ghosh, S., Giri, S. K., Hothi, I., Höfer, C., Iliev, I. T., Jelić, V., Ma, Q., Mellema, G., …Yatawatta, S. (2025). Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1. Astronomy and Astrophysics, 698, Article A186. https://doi.org/10.1051/0004-6361/202554158+

We present new upper limits on the 21-cm signal power spectrum from the Epoch of Reionization (EoR), at redshifts í µí± § ≈ 10.1, 9.1, and 8.3, based on reprocessed observations from the Low-Frequency Array (LOFAR). The analysis incorporates signific... Read More about Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1.

Reproducibility of machine learning analyses of 21 cm reionization maps (2024)
Journal Article
Sooknunan, K., Chapman, E., Conaboy, L., Mortlock, D. J., & Pritchard, J. R. Reproducibility of machine learning analyses of 21 cm reionization maps. Manuscript submitted for publication

Machine learning (ML) methods have become popular for parameter inference in cosmology, although their reliance on specific training data can cause difficulties when applied across different data sets. By reproducing and testing networks previously u... Read More about Reproducibility of machine learning analyses of 21 cm reionization maps.

The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations (2024)
Journal Article
Feron, J., Conaboy, L., Bolton, J. S., Chapman, E., Haehnelt, M. G., Keating, L. C., Kulkarni, G., & Puchwein, E. (2024). The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations. Monthly Notices of the Royal Astronomical Society, 532(2), 2401-2417. https://doi.org/10.1093/mnras/stae1636

Recent evidence supporting reionization ending at redshift z ≲ 6 includes the rapid redshift evolution of the mean free path, λmfp , for Lyman-limit photons through the intergalactic medium (IGM) at 5 < z < 6. Here, we investigate λmfp predicted by t... Read More about The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations.

Detecting the H I power spectrum in the post-reionization Universe with SKA-Low (2023)
Journal Article
Chen, Z., Chapman, E., Wolz, L., & Mazumder, A. (2023). Detecting the H I power spectrum in the post-reionization Universe with SKA-Low. Monthly Notices of the Royal Astronomical Society, 524(3), 3724-3740. https://doi.org/10.1093/mnras/stad2102

We present a survey strategy to detect the neutral hydrogen (H I) power spectrum at 5 < z < 6 using the SKA-Low radio telescope in presence of foregrounds and instrumental effects. We simulate observations of the inherently weak H I signal post-reion... Read More about Detecting the H I power spectrum in the post-reionization Universe with SKA-Low.

First Light: Switching on Stars at the Dawn of Time (2022)
Journal Article
Chapman, E. (2022). First Light: Switching on Stars at the Dawn of Time. Contemporary Physics, 63(1), 15-33. https://doi.org/10.1080/00107514.2022.2133417

The Era of the First Stars is one of the last unknown frontiers for exploration: a poorly understood billion years missing from our cosmological timeline. We have now developed several methods for finally filling in the lost billion years of the hist... Read More about First Light: Switching on Stars at the Dawn of Time.

First light: switching on stars at the dawn of time (2022)
Journal Article
CHAPMAN, E. (2022). First light: switching on stars at the dawn of time. Contemporary Physics, 63(1), 15-33. https://doi.org/10.1080/00107514.2022.2133417

The Era of the First Stars is one of the last unknown frontiers for exploration: a poorly understood billion years missing from our cosmological timeline. We have now developed several methods for finally filling in the lost billion years of the hist... Read More about First light: switching on stars at the dawn of time.

A star is reborn: how Hubble astronomers saw the earliest light (2022)
Newspaper / Magazine
Chapman, E. (2022). A star is reborn: how Hubble astronomers saw the earliest light

A tiny smudge on the space telescope turned out to be starlight from Earendel, almost 13 billion years old – revealing evidence of the universe in its infancy