Reionization with star-forming galaxies: insights from the Low-z Lyman Continuum Survey

Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19

Maxime Trebitsch Pratika Dayal John Chisholm Steven L. Finkelstein Anne Jaskot Sophia Flury Daniel Schaerer Hakim Atek Sanchayeeta Borthakur Harry Ferguson Fabio Fontanot Mauro Giavalisco Andrea Grazian Matthew Hayes Floriane Leclercq Göran Östlin Alberto Saldana-Lopez Trinh X. Thuan Bingjie Wang Gábor Worseck

Abstract： The fraction of ionizing photons escaping from galaxies, $f_{esc}$, is at the same time a crucial parameter in modelling reionization and a very poorly known quantity, especially at high redshift. Recent observations are starting to constrain the values of $f_{esc}$ in low-z star-forming galaxies, but the validity of this comparison remains to be verified. Applying at high-z the empirical relation between $f_{esc}$ and the UV slope trends derived from the Low-z Lyman Continuum Survey, we use the DELPHI semi-analytical galaxy formation model to estimate the global ionizing emissivity of high-z galaxies, which we use to compute the resulting reionization history. We find that both the global ionizing emissivity and reionization history match the observational constraints. Assuming that the low-z correlations hold during the epoch of reionization, we find that galaxies with $-16 \lesssim M_{UV} \lesssim -13.5$ are the main drivers of reionization. We derive a population-averaged $\langle f_{esc} \rangle \simeq 8\%, 10\%, 20\%$ at z=4.5, 6, 8.

Peer Review Status:Awaiting Review

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