Why Use uvmcmcfit?

Here are three reasons why you might be interested in using uvmcmcfit.

Markov Chain Monte Carlo

uvmcmcfit uses D. Foreman-Mackey’s emcee to do Markov Chain Monte Carlo (MCMC). emcee is an affine-invariant MCMC ensemble sampler that is efficient at identifying the best-fit model and the uncertainties on the parameters of the model.

Interferometry

Interferometers measure visibilities, not images. In many situations (e.g., strong gravitational lensing), it is advantageous to measure the goodness of fit from the visibilities rather than the deconvolved images.

uvmcmcfit includes a pure-Python adaptation of Miriad’s uvmodel task that allows it to generate simulated visibilities given observed visibilities and a model image.

Gravitational Lensing

Many of the brightest galaxies that have been observed by interferometers are gravitationally lensed by an intervening galaxy or group of galaxies along the line of sight. Understanding the intrinsic properties of the lensed galaxies requires a lens model.

uvmcmcfit includes a simple ray-tracing routine that allows it to account for both strongly lensed systems (where multiple images of the lensed galaxy are detected) and weakly lensed systems (where only a single image of the lensed galaxy is detected).