Symposium S1  29-30 June 2022

The Universe at the reionization epoch

News: Web page for the symposium under construction. List of invited speakers to be published soon.

Aims and scope

The Reionization of the Universe is the latest change of phase that the Universe underwent when it was only a few hundreds of million years old. So far we do not understand yet which sources produced the reionization, with an open debate about the relative role of UV luminous vs. UV weak galaxies, nor how long it took. All we seem to agree on is that the reionization was mostly completed by around z ~ 6, though some large neutral regions could have survived longer. However there are many questions that we do not understand yet, like the role of AGN, if any at this time, or the ionizing luminosity escape fraction of galaxies, which determines directly the pace of the reionization. Some questions could be answered by identifying proxies at lower redshifts of the galaxies that produced the reionization. On the other hand, the identification of Lyman alpha emitters before the end of the reionization shows that many of these sources seem to have produced individual ionized bubbles, large enough to allow the escape of Lyman alpha photons not affected by scattering on the Inter Galactic Medium. Are these bubbles the seeds that through percolation completed the reionization of the universe by z~6? How was the reionization produced? Which are the factors to take into account when studying the reionization?


Topics for which we would like to receive requests for contributed talks:

  • First galaxies
    Nicolas Laporte "First galaxies"
    - Formation of first galaxies
    Maxime Trebitsch "The role of AGN vs stars in the reionization"
    - Lyman continuum sources: Pop III stars, primeval AGN, ionising spectrum,...
  • Lyman continuum escape
    Anne Jaskot "Insights from Low-Redshift Lyman Continuum Emitters"
    - What drives the escape of ionising photons to the IGM at any time?
    - Relation between LyC and Ly alpha escape processes
    - Analogues of Lyman continuum leakers at low redshift
    Harley Katz "Title TBD"
    - Tracers of Lyman continuum leaking at z>6
  • Constraining the reionization process
    Eduard Salvador-Solé "Single vs. double reionization of the Universe"
    - Modelling the reionization of the Universe
    Marco Castellano "Observations of re-ionized bubbles"
    - The formation and evolution of ionized bubbles
    - Factors driving the visibility of Lyman alpha emission at high redshift

Invited speakers

  • Anne Jaskot Williams College
  • Eduard Salvador-Solé Universidad de Barcelona
  • Harley Katz University of Oxford
  • Marco Castellano Osservatorio Astronomico de Roma
  • Maxime Trebitsch Rijksuniversiteit Groningen
  • Nicolas Laporte University of Cambridge

Scientific organisers

Anne Verhamme (UniGe) Geneva (co-Chair)
J. Miguel Mas-Hesse (CAB) Madrid (co-Chair)
Hakim Atek (IAP) Paris
Pratika Dayal (RUG) Groningen
Jesús Gallego (UCM) Madrid
Matthew Hayes (SU) Stockholm
Daniel Kunth (IAP) Paris
Alberto Manrique (UB) Barcelona
Charlotte Mason (NBI) Copenhagen
Göran Östlin (SU) Stockholm
Roser Pelló (LAM) Marseille
Laura Pentericci (INAF-OR) Roma
J. Miguel Rodríguez-Espinosa (IAC) Tenerife


SOC co-chairs:
Anne Verhamme Anne.Verhamme @
J. Miguel Mas-Hesse mm @

Updated on Fri Jan 14 12:48:34 CET 2022