Dark Energy models¶

class
camb.dark_energy.
DarkEnergyModel
[source]¶ Abstract base class for dark energy model implementations.

class
camb.dark_energy.
DarkEnergyEqnOfState
[source]¶ Bases:
camb.dark_energy.DarkEnergyModel
Abstract base class for models using w and wa parameterization with use w(a) = w + (1a)*wa parameterization, or call set_w_a_table to set another tabulated w(a). If tabulated w(a) is used, w and wa are set to approximate values at z=0.
See
model.CAMBparams.set_initial_power_function()
for a convenience constructor function to set a general interpolated P(k) model from a python function.Variables:  w – (float64) w(0)
 wa – (float64) dw/da(0)
 cs2 – (float64) fluid restframe sound speed squared
 use_tabulated_w – (boolean) using an interpolated tabulated w(a) rather than w, wa above

class
camb.dark_energy.
DarkEnergyFluid
[source]¶ Bases:
camb.dark_energy.DarkEnergyEqnOfState
Class implementing the w, wa or splined w(a) parameterization using the constant soundspeed single fluid model (as for singlefield quintessense).

class
camb.dark_energy.
DarkEnergyPPF
[source]¶ Bases:
camb.dark_energy.DarkEnergyEqnOfState
Class implementating the w, wa or splined w(a) parameterization in the PPF perturbation approximation (arXiv:0808.3125) Use inherited methods to set parameters or interpolation table.

class
camb.dark_energy.
Quintessence
[source]¶ Bases:
camb.dark_energy.DarkEnergyModel
Abstract base class for single scalar field quintessence models.
For each model the field value and derivative are stored and splined at sampled scale factor values.
To implement a new model, need to define a new derived class in Fortran, defining Vofphi and setting up initial conditions and interpolation tables (see TEarlyQuintessence as example).
Variables:  DebugLevel – (integer)
 astart – (float64)
 integrate_tol – (float64)
 sampled_a – (float64 array)
 phi_a – (float64 array)
 phidot_a – (float64 array)

class
camb.dark_energy.
EarlyQuintessence
[source]¶ Bases:
camb.dark_energy.Quintessence
Example early quintessence (axionlike, as arXiv:1908.06995) with potential
V(phi) = m^2f^2 (1  cos(phi/f))^2 + Lambda_{cosmological constant}Variables:  n – (float64) power index for potential
 f – (float64) f/Mpl (sqrt(8piG)f); only used for initial search value if use_zc is True
 m – (float64) mass parameter in reduced Planck mass units; only used for initial search value of use_zc is True
 theta_i – (float64) phi/f initial field value
 frac_lambda0 – (float64) fraction of dark energy in cosmologicla constant today (approximated as 1)
 use_zc – (boolean) solve for f, m to get specific critical reshidt zc and fde_zc
 zc – (float64) reshift of peak fractional early dark energy density
 fde_zc – (float64) fraction of early dark energy density to total at peak
 npoints – (integer) number of points for background integration spacing
 min_steps_per_osc – (integer) minimumum number of steps per background oscillation scale
 fde – (float64 array) after initialized, the calculated backgroundearly dark energy fractions at sampled_a

class
camb.dark_energy.
AxionEffectiveFluid
[source]¶ Bases:
camb.dark_energy.DarkEnergyModel
Example implementation of a specifc (early) dark energy fluid model (arXiv:1806.10608). Not well tested, but should serve to demonstrate how to make your own custom classes.
Variables:  w_n – (float64) effective equation of state parameter
 fde_zc – (float64) energy density fraction at z=zc
 zc – (float64) decay transition redshift (not same as peak of energy density fraction)
 theta_i – (float64) initial condition field value