gwnr.cosmo — cosmology

Cosmological conversions used in GW population and rates work. Source: gwnr/cosmo/utils.py.

1. Redshift and frame conversions
   1. calculate_redshift(distance, h=0.679, om=0.3065, ol=0.6935, w0=-1.0)
   2. source_to_detector_frame(m, z) / detector_to_source_frame(m, z)
2. Redshift distributions for populations
3. Background cosmology

Redshift and frame conversions

calculate_redshift(distance, h=0.679, om=0.3065, ol=0.6935, w0=-1.0)

Redshift from luminosity distance using LAL’s cosmology calculator. Defaults are the Planck 2015 TT+lowP+lensing+ext parameters (arXiv:1502.01589, Table 4): Ω_M = 0.3065, Ω_Λ = 0.6935, H₀ = 67.9 km/s/Mpc. Accepts arrays.

source_to_detector_frame(m, z) / detector_to_source_frame(m, z)

Convert masses between source frame and detector frame: m_det = m_src (1 + z).

Redshift distributions for populations

Tools to draw merger redshifts assuming a rate density uniform in comoving volume:

• make_z_cosmo_inverseCDF(z_max, R0, H0, Omega_m, Omega_Lambda, Omega_k, w0, w1) — build the inverse CDF of the redshift distribution up to z_max for local rate R0.
• z_samples_from_iCDF(iCDF, N) — draw N redshift samples through the inverse CDF.
• probability_density_Uniform_comoving_volume(z, ...) — the corresponding pdf.
• dR_dz(z, ...), dV_dz(z, ...) — differential merger rate and comoving-volume element.

Background cosmology

Low-level functions parameterized by (H₀, Ω_m, Ω_Λ, Ω_k, w₀, w₁), supporting an evolving dark-energy equation of state:

H(z, ...), OneOverH(z, ...), E(z, w0, w1), Hubble_integral(z_prime, ...), DL(z, ...) and its vectorized form DL_vector(z_arr, ...) — Hubble rate, dimensionless dark-energy factor, comoving-distance integral, and luminosity distance.