Kavli Affiliate: Martin Haehnelt
| First 5 Authors: Moupiya Maji, Anne Verhamme, Joakim Rosdahl, Thibault Garel, Jeremy Blaizot
| Summary:
The primary difficulty in understanding the sources and processes that
powered cosmic reionization is that it is not possible to directly probe the
ionizing Lyman Continuum (LyC) radiation at that epoch as those photons have
been absorbed by the intervening neutral hydrogen in the IGM on their way to
us. It is therefore imperative to build a model to accurately predict LyC
emission using other properties of galaxies in the reionization era.
In recent years, studies have shown that the LyC emission from galaxies may
be correlated to their Lya emission. Here, we study this correlation by
analyzing thousands of galaxies at high-z in the SPHINX cosmological
simulation. We post-process these galaxies with the Lya radiative transfer code
RASCAS and analyze the Lya – LyC connection.
We find that the Lya and LyC luminosities are strongly correlated with each
other, although with dispersion. There is a positive correlation between Lya
and LyC escape fractions in the brightest Lya emitters (>$10^{41}$ erg/s),
similar to the recent observational studies. However, when we also include
fainter Lya emitters (LAEs), the correlation disappears, which suggests that
the observed relationship may be driven by selection effects. We also find that
bright LAEs are dominant contributors to reionization ($> 10^{40}$ erg/s
galaxies contribute $> 90%$ of LyC emission). Finally, we build predictive
models using multivariate linear regression where we use the physical and the
Lya properties of simulated galaxies to predict their intrinsic and escaping
LyC luminosities with a high degree of accuracy. We find that the most
important galaxy properties to predict the escaping LyC luminosity of a galaxy
are its escaping Lya luminosity, gas mass, gas metallicity, and SFR.
These models can be very useful to predict LyC emissions from galaxies and
can help us identify the sources of reionization.
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