Answer to Question #89597 in Astronomy | Astrophysics for sathwik

Question

Difference between the density bounded medium and the picket fence model

Answer 1

Lyman continuum radiation can be allowed to escape a galaxy mainly by two means. In one case, the source region scan be surrounded by a largely isotropic gas with a sufficiently low column density of neutral hydrogen HI to not completely attenuate the passing Lyman-continuum radiation. This is usually referred to as the density-bounded medium. In second case, the neutral medium is optically thick, but does not completely cover the ionizing sources. This scenario has been referred to as the picket fence model,or the ionization-bounded medium with holes.