Gravitational-wave inference
Basic configuration
nessai
includes a default configuration for gravitational-wave inference. This includes default reparameterisations for common parameters. This functionality is enabled by adding flow_class='gwflowproposal'
to the arguments for the sampler.
Marginalisation
Distance marginalisation
In the original paper we tested nessai
with and without distance marginalisation and found that it can work with either. With the updated defaults, sampling with distance marginalisation is typically faster.
Phase marginalisation
The current defaults for nessai
are not well suited to sampling without phase marginalisation and these result in inefficient sampling. We believe that revised settings for this case will help and we are actively investigating this.
Time marginalisation
Time marginalisation as implemented in bilby
has been tested and results show that it can reduce sampling time without negatively impacting convergence.
The time_jitter
parameter that is added by bilby
is treated as a periodic parameter by default, however it is not clear is this treatment is necessary.
Calibration parameters
Basic tests including calibration parameters have been conducted and no major issues have been identified. Sampling is, as expected, slower but the overall convergence does not seem to be affected.
These parameters typically use Gaussian priors without hard prior bounds. By default, this is not an issue because the NullReparameterisation
is used. However, if using a custom set of reparameterisations this should be accounted for.
Examples
Examples of running nessai
for gravitational-wave inference can be found in the GW examples directory here.