An ionised bubble powered by a proto-cluster at z = 6.5

Artistic rendition of the re-ionisation process. Each dot is a galaxy, which ionises its surroundings forming a bubble. These bubbles can grow depending of the ionising power of each galaxy. If the galaxies are close together the bubbles can merge and form a much larger bubble. With time all the bubbles will merge till the Universe become re-ionised. Ionisation is the process under which high energy photons from the galaxies kick out the electron from the neutral hydrogen atoms thus leaving them ionised.
Each dot is a galaxy that ionises its surroundings forming a bubble. These bubbles can grow depending of the galaxy ionising power and the bubbles can merge forming a larger bubble. With time all the bubbles will merge till the Universe become re-ionised.
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Authors
J. M. Mas-Hesse
Centro de Astrobiología - INTA-CSIC
E. Salvador-Solé
Institut de Ciencies del Cosmos
R. Calvi
Instituto de Astrofísica de Canarias (IAC)
A. Manrique
Institut de Ciencies del Cosmos
K. Chanchaiworawit
University of Florida
R. Guzman
University of Florida
J. Gallego
Universidad Complutense de Madrid
A. Marín Franch
Centro de Estudios de Física del Cosmos de Aragón
References
2020 MNRAS 495 L17

We show herein that a proto-cluster of Lyα emitting galaxies, spectroscopically confirmed at redshift 6.5, produces a remarkable number of ionising continuum photons. We start from the Lyα fluxes measured in the spectra of the sources detected spectroscopically. From these fluxes we derive the ionising emissivity of continuum photons of the proto-cluster, which we compare with the ionising emissivity required to reionise the proto-cluster volume. We find that the sources in the proto-cluster are capable of ionising a large bubble, indeed larger than the volume occupied by the proto-cluster. For various calculations we have used the model AMIGA, in particular to derive the emissivity of the Lyman continuum photons required to maintain the observed volume ionised. Besides, we have assumed the ionising photons escape fraction given by AMIGA at this redshift.

News type
Research news
Scope
Science and Technology
Severo Ochoa
SO Research
Astrophysics
Undergraduate
Teachers
Scientists
Formation & Evolution of Galaxies (FYEG)
SEVERO OCHOA

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