An ionised bubble before the epoch of re-ionisation

Date and time
14 Apr 2020 - 12:30 Europe/London


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Re-ionisation followed the dark ages when enough stars and galaxies had been formed that their ionising output was sufficient for the task. Population III stars and star-forming galaxies started the re-ionisation process by forming primordial bubbles of ionised gas. These bubbles grew, illuminated by galaxies with strong Lyman continuum, and merged, till the entire Universe became ionised. The epoch corresponding to red-shift 6.5 is especially interesting as we now know the Universe became re-ionised by redshift ~5.5-6. High-z Lyα emitters are perhaps the most important witnesses of the re-ionisation process. Indeed, at redshifts larger than 6, Lyα sources would be undetectable, unless they are located within sizeable bubbles of ionised gas. I will show that a proto-cluster of Lyα emitting galaxies, spectroscopically confirmed at redshift 6.5, is within one such large ionised super-bubble. The kinds of bubbles that through percolation completed the re-ionisation of the universe.


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