CosmoFit.BA

class CosmoFit.BA(params)

Bases: Cosmology

Barboza-Alcaniz (BA) dark-energy model.

Equation of state

w(z) = w0 + wa * z * (1 + z) / (1 + z^2)

Designed to stay finite (-> w0 - wa as z -> infinity, rather than diverging or saturating) at arbitrarily high redshift unlike CPL, which several papers cite as a theoretical advantage when extrapolating w(z) into the matter/radiation era. Reuses the CPL/wCDM w0/wa parameters – no new free parameters.

Reference

Barboza & Alcaniz (2008), Phys. Lett. B 666, 415, arXiv:0805.1713.

__init__(params)

Parameters:

params (CosmologyParameters)

Methods

E(z)	Dimensionless Hubble parameter.
H(z)
Omega_de(z)	Dark-energy density parameter.
Omega_matter(z)	Matter density at redshift z, in units of today's critical density -- i.e. the Omega_m (1+z)^3 term as it appears inside E(z)^2, before dividing by E(z)^2.
__init__(params)
dEdz(z)	Derivative of E(z).
fde(z)	Dark-energy density evolution factor.
mu(a[, k])	Effective-to-Newtonian gravitational coupling ratio, G_eff(a,k)/G_N, entering the linear growth equation solved by GrowthCalculator (see that module's docstring for the equation itself).
plain_name()	This model's name as plain text: MODEL_NAME if it declares one, else the class name.
plot_label()	This model's name as it should appear in a figure legend or title -- MODEL_LABEL (LaTeX) if it declares one, else plain_name().
refresh()	Rebuild internal numerical tables after the underlying params object has been mutated in place (e.g. by params.update(theta) during an MCMC step).
w(z)	Dark-energy equation of state.

Attributes

A_planck
A_s
EXTRA_PARAMS	Extra parameters this model adds beyond CosmologyParameters.
H0
MB
MODEL_LABEL	a LaTeX math string where the plain name is really a set of symbols (LCDM -> $\Lambda$CDM), None where the plain name is already what a reader should see (an acronym like CPL).
MODEL_NAME	Plain-text name for this model, for tables, JSON and log lines.
N_eff
Omega_b
Omega_de0
Omega_k
Omega_m
alpha
compute_rd	Whether rd is computed from the physical densities (rd_computed()) rather than read from the free rd parameter.
derive_sigma8	Whether sigma8 is derived from the Boltzmann code rather than read from the free sigma8 parameter.
h	Reduced Hubble constant, H0 / 100.
ln1e10As
m_nu
n_s
omega_b_h2	Physical baryon density, Omega_b h^2 -- the combination BBN and the CMB actually constrain.
omega_cdm_h2	Physical cold dark matter density, Omega_c h^2 -- matter less baryons.
omega_m_h2	Physical matter density, Omega_m h^2.
rd	The sound horizon at the drag epoch [Mpc] that the BAO likelihoods divide by.
sigma8	Present-day sigma_8, the normalization every growth prediction is built on.
tau_reio
w0
wa

Parameters:

params (CosmologyParameters)