Function greens_function_photon

pub fn greens_function_photon(
    x_obs: f64,
    x_inj: f64,
    z_h: f64,
    sigma_x: f64,
    cosmo: &Cosmology,
) -> f64

Green’s function for monochromatic photon injection.

Returns Δn(x_obs) per unit ΔN/N injected at frequency x_inj and redshift z_h. Uses the universal μ-y visibility function J_μ(z) (same as heat injection) to blend between pure μ-era and pure y-era contributions.

Structure:

G_ph = J_μ · G_μ + (1 − J_μ) · G_y

where G_μ is the μ-era contribution (M + G_bb terms) and G_y is the y-era contribution (Y_SZ + surviving bump).

When P_s = 0 (soft photon limit), reduces to α_ρ × x_inj × G_th(x, z_h).

Arguments

• x_obs - observation frequency
• x_inj - injection frequency
• z_h - injection redshift
• sigma_x - extra Gaussian width for the surviving bump (0 for pure Compton)
• cosmo - cosmological parameters (for Compton y_γ)

References: Chluba (2015), arXiv:1506.06582