Likelihood Functions

class radvel.likelihood.Likelihood(model, x, y, yerr, extra_params=[], decorr_params=[], decorr_vectors=[])

Generic Likelihood

class radvel.likelihood.RVLikelihood(model, t, vel, errvel, suffix='', decorr_vars=[], decorr_vectors=[])

RV Likelihood

The Likelihood object for a radial velocity dataset

Parameters:

• model (radvel.model.RVModel) – RV model object
• t (array) – time array
• vel (array) – array of velocities
• errvel (array) – array of velocity uncertainties
• suffix (string) – suffix to identify this Likelihood object useful when constructing a CompositeLikelihood object.

errorbars()

Return uncertainties with jitter added in quadrature.

Returns:uncertainties Return type:array

logprob()

Return log-likelihood given the data and model. Priors are not applied here.

Returns:Natural log of likelihood Return type:float

residuals()

Residuals

Data minus model

radvel.likelihood.loglike_jitter(residuals, sigma, sigma_jit)

Log-likelihood incorporating jitter

See equation (1) in Howard et al. 2014. Returns loglikelihood, where sigma**2 is replaced by sigma**2 + sigma_jit**2. It penalizes excessively large values of jitter

Parameters:

• residuals (array) – array of residuals
• sigma (array) – array of measurement errors
• sigma_jit (float) – jitter

Returns:

log-likelihood

Return type:

float