# The production and escape of ionizing photons from galaxies over cosmic time (Astro2020 Science White Paper)

## TL;DR

This white paper discusses the importance of ionizing photons in galaxy evolution, emphasizing the need for advanced spectroscopic observations to understand their production, escape mechanisms, and evolution over cosmic time.

## Contribution

It highlights the potential of upcoming space-based and ground-based spectroscopy to resolve key questions about ionizing photon escape in galaxies.

## Key findings

- Spectroscopic capabilities will clarify photon production mechanisms.
- Observations will identify galaxy populations responsible for ionizing photon leakage.
- Studies will reveal how ionizing photon escape evolves over cosmic time.

## Abstract

The ionizing photons produced by massive stars are key actors in galaxy evolution. Ionizing photon production and escape is poorly understood. Improved space-based, spatially-resolved, multiplexed spectroscopic capabilities covering observed wavelengths of 1000 to 3000 Angstrom, in concert with spectroscopy from the ELTs and JWST, would lead to definitive answers as to how ionizing photons are produced and leaked, what populations of galaxies are responsible for ionizing photon leakage, what determines whether escape is possible, and how ionizing galaxy populations evolve over cosmic time.

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Source: https://tomesphere.com/paper/1905.05566