Priors
Redback uses bilby
under the hood for priors. See here for general documentation of priors in bilby
.
Analytical priors
Thanks to bilby
there are several different priors already implemented.
Beta
Categorical
Cauchy
ChiSquared
Cosine
DeltaFunction
Exponential
FermiDirac
Gamma
Gaussian
HalfGaussian
LogGaussian
LogUniform
Logistic
Lorentzian
PowerLaw
Sine
StudentT
SymmetricLogUniform
TruncatedGaussian
Uniform
Interpolated or from file
Users can also create a prior from a grid of values i.e., an interpolated_prior. See documentation here.
Constrained priors
Sometimes there are some additional constraints on the priors that are difficult to parameterise or not on a sampled parameter.
For example, the rotational energy of a neutron star cannot be exceeded in a super luminous supernova. Or that a numerical surrogate is only valid in a certain domain etc. In redback, we have written several of these constraints which can be used by simply loading the particular constraint from redback.constraints and passing them to the bilby prior dictionary.
For example,
import redback
from bilby.core.prior import PriorDict, Uniform, Constraint
priors = PriorDict(conversion_function=redback.constraints.slsn_constraint)
priors['erot_constraint'] = Constraint(minimum=0, maximum=100)
priors['t_nebula_min'] = Constraint(minimum=0, maximum=100)
Then define our priors on all other parameters in the normal way.
You can implement your own constraints by following the constraint templates and bilby
documentation.