H₂ Formation‑Rate Explorer

Zeta1 cube 7, 128³, 200 pc box. The relation is two power laws in total column; G₀, ζ and F move only where they meet. Everything else — both slopes, both offsets, the transition width — is held fixed while you drag them.

log N_trans = log N_trans,fid + 1.07 log(G₀/G₀^fid) + 0.08 log(ζ/ζ^fid) + 0.21 log(F/F^fid)

Parameters

Controls

Projection axis

Hold the model J_F colour scale at the measured range, so the two maps are directly comparable Show binned mode points with their scatter on the relation plot

Pin the fiducial curve, then raise G₀ by half a dex and lower α₂: the dense branch lands almost back on the pin. That is the degeneracy between transition column and dense-branch slope. Hover the relation plot to read the model off the track.

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log N_21,trans—

N_trans—

A_V—

sightlines past—

column past—

rms vs measured—

Projected maps · 128² sightlines

Total column density

log N_H [cm⁻²]. Fixed by the simulation; the contour marks N_trans.

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Formation rate

log J_F integrated along the axis, from n_HI n_H R(T).

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Effective formation rate against column density

current model fiducial pinned diffuse branch dense branch ● binned modes ± scatter · greyscale = measured sightline density