HII Regions Escape Fractions

Class providing models of the escape fraction \(f_\mathrm{esc}\) of hydrogen-ionizing (Lyman-continuum) photons from individual H**ii** regions—the fraction of photons produced by massive stars that escape the H**ii** region into the surrounding ISM or IGM rather than being absorbed by gas within the region. The escape fraction is returned as a function of H**ii** region age, reflecting the time evolution as stellar winds and supernovae clear channels through the surrounding gas.

Default implementation: hiiRegionEscapeFractionFixed

Methods

escapeFraction → double precision

Returns the escape fraction for hydrogen-ionizing photons.

  • double precision, intent(in ) :: ageHIIRegion

hiiRegionEscapeFractionFixed

Computes the escape fraction of hydrogen ionizing photons from HII regions. A fixed escape fraction of \(f_\mathrm{esc}\)[escapeFraction] is assumed for HII regions with ages less than \(\tau_\mathrm{limit}=\){ageLimit}.

(Default implementation)

Parameters

  • [escapeFraction] (real; default 0.006d0) — Escape fraction of ionizing photons from young HII regions.

  • [ageLimit] (real; default 0.03d0) — The age beyond which all ionizing photons are assumed to escape from HII regions.