Escape of Lyman radiation from galactic labyrinths
26-29 April 2016, OAC, Kolymbari, Crete

Rationale
The genesis and escape of Lyman alpha and continuum radiation on galactic and sub-galactic scales is a result of a complex and subtle interplay between the dynamical constituents of evolving galaxies. Whereas the Lyman radiation produced by massive stars, AGN and shocks has been studied in detail, our knowledge on how Lyman photons, once they are produced, are reprocessed within a galaxy is woefully incomplete, especially when it comes to the mechanisms facilitating and regulating their escape into the galactic halo and beyond.

On sub-galactic scales, the pathways of Lyman photons from young stellar clusters and HII regions into the ambient diffuse ionized gas, and their imprints on the physical properties of the multi-phase ISM are still obscure. On galactic scales, the scattering Odyssey of Lyman-alpha photons from their birthplace out to the galactic halo remains to be written. How feedback processes shape the 3D structure, chemical abundance patterns and kinematics of the gas along that route and what mechanisms regulate the escape of Lyman photons out of the galaxy labyrinth is an unsolved enigma. Similarly, how Lyman photon escape, and its evolution with time are related to the growth of galaxies and to various star-formation rate indicators remains a longstanding puzzle.

The escape fraction of Lyman radiation along the co-evolution of AGN with their galaxy hosts and in different environments - from evolving HII regions all the way to galaxy mergers and massive early-type galaxies - are further examples of subjects with key astrophysical relevance where our knowledge is largely incomplete.

A final question concerns how escaping Lyman radiation illuminates the cosmic web and may influence galaxy evolution over larger cosmic volumes?

The meeting aims at bringing observers and theoreticians together towards a joint exploration of the Odyssey that Lyman radiation undergoes as it attempts to escape the galaxy labyrinth. This meeting is motivated by astrophysically important questions, such as:

• how is the assembly history of galaxies and evolving physical properties of their multi-phase ISM related to the escape fraction of Lyman photons?
• how does the escape of Lyman radiation evolve with the rise and fall of star-forming and accretion-powered nuclear activity in galaxies, and what imprints does Lyman photon escape from galaxies leave on the intergalactic medium and the cosmic web?
• what modeling concepts and observational constraints are most needed for achieving a breakthrough in our understanding of Lyman photon escape both at sub-galactic and galactic scales?

Thematic units

1. Production and transport of Lyman radiation
2. Reprocessing and escape of Lyman radiation on sub-galactic scales
3. Lyman photon escape in star-forming galaxies
4. Lyman photon escape in the presence of accretion-powered nuclear activity in galaxies
5. Lyman photons in the cosmic web
6. Challenges and opportunities: observational and theoretical input towards a better understanding of Lyman photon escape over cosmic time

Confirmed Key Speakers
Dominik J. Bomans (Astronomical Institute, Ruhr-University Bochum, Germany)
Sebastiano Cantalupo (ETH Zürich, Switzerland)
Paul Crowther (Sheffield University, UK)
Dawn Erb (University of Wisconsin Milwaukee, USA)
Jeffrey Kenney (Yale University, USA)
Sally Oey (University of Michigan, USA)
Martin M. Roth (Leibniz-Institut für Astrophysik Potsdam - AIP, Germany)
Claudio dalla Vecchia (IAC, Spain)
Anne Verhamme (Observatoire de Genève, Switzerland)