分类： 天文学 >> 天文学 提交时间： 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
摘要： 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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Bingjie Wang
Timothy M. Heckman
Ricardo Amorín
Sanchayeeta Borthakur
John Chisholm
Harry Ferguson
Sophia Flury
Mauro Giavalisco
Andrea Grazian
Matthew Hayes
Alaina Henry
Anne Jaskot
Zhiyuan Ji
Kirill Makan
Stephan McCandliss
M. S. Oey
Göran Östlin
Alberto Saldana-Lopez
Daniel Schaerer
Trinh Thuan
摘要： The relationship between galaxy characteristics and the reionization of the universe remains elusive, mainly due to the observational difficulty in accessing the Lyman continuum (LyC) at these redshifts. It is thus important to identify low-redshift LyC-leaking galaxies that can be used as laboratories to investigate the physical processes that allow LyC photons to escape. The weakness of the [S II] nebular emission lines relative to typical star-forming galaxies has been proposed as a LyC predictor. In this paper, we show that the [S II]-deficiency is an effective method to select LyC-leaking candidates using data from the Low-redshift LyC Survey, which has detected flux below the Lyman edge in 35 out of 66 star-forming galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. We show that LyC leakers tend to be more [S II]-deficient and that the fraction of their detections increases as [S II]-deficiency becomes more prominent. Correlational studies suggest that [S II]-deficiency complements other LyC diagnostics (such as strong Lyman-$\alpha$ emission and high [O III]/[O II]). Our results verify an additional technique by which reionization-era galaxies could be studied.
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