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Table 1

Summary of the regimes found in a static, clumpy medium.

Name Requirementa Nclb xpc Description

Free-streaming τ0,total ≲ 1 fc ~ 0 Photons stream through clumps
Porous (τ0,total ≳ 1) ∧ (fc ≲ 1) ~ 0 ~ 0 Escape through holes without interaction
Random-walk fc2 ~ 0 Scatter off clumps until escape
Homogeneous { fc ~ xesc A Excursion-like escape
fc ~ x B Escape in a single flight

Notes. The regimes are described in detail in Sect. 2.3.


Parameter space of regime. Visualized in Fig. 1.


Average number of clumps a photon encounters before escape.


Dominant frequency of escape.


Escape frequency from a homogeneous slab (Eq. (5)).


Boundary between core and wing of the line. x ~ 3.26 for T = 104K.

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