Seminar @ DF-AS - S. Bosman - The influence of galaxies on the epoch of reionisation

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10/24/2018 - 11:30
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10/24/2018 - 12:30
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Much debate is occurring around the role of galaxies in reionising the Universe at z>6. Studies of neutral hydrogen absorption towards high-redshift quasars have revealed large homogeneities in Lyman-alpha opacity among lines of sight at the same redshift, which persist much later than predicted by the first faint galaxies-driven reionisation models. A greater role in driving reionisation of rare bright sources, such as quasars, relieves this issue but clashes with other observations such as the quasar luminosity function and IGM temperature. Recently, more refined models of galaxy-driven reionisation may have also started to solve this issue by employing hydrodynamical simulations with radiative transfer in larger simulation volumes. At the same time, new techniques to probe the effect of galaxies on reionisation more directly have emerged. These experiments aim to connect Lyman-alpha opacity with galaxies detected in the same cosmic volume. I will discuss these recent developments, including (i) the dearth of detected Lyman-alpha emitters in the most Lyman-alpha opaque cosmic volume at z~5.7, and implication for UVB fluctuations; (ii) studies using the number of galaxies and their distance from Lyman-alpha lines-of-sight to constrain the ionising emissivity and escape fractions of these sources.


Villa Bazzoni


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Last update: 10-22-2018 - 11:46