Code motivation

The launch of new telescopes/surveys is leading to an explosion of transient observations. Redback is a software package that enables end-to-end interpretation and parameter estimation of these transients. Redback is built with an object-oriented modular approach. This ensures that users can use different parts of redback for their own use without needing to interact with other parts.

How redback can be useful to you

  • Download data for supernovae, tidal disruption events, gamma-ray burst afterglows, kilonovae, prompt emission from different catalogs/telescopes; Swift, BATSE, Open access catalogs, FINK and LASAIR brokers. Users can also provide their own data or use simulated data

  • Redback processes the data into a homogeneous transient object. Making it easy to plot lightcurves and do any other processing.

  • The user can then fit one of the models implemented in redback. Or fit their own model. Models for several types of electromagnetic transients are implemented and range from simple analytical models to numerical surrogates.

  • All models are implemented as functions and can be used to simulate populations, without needing to provide data. This way redback can be used simply as a tool to simulate realistic populations, no need to actually fit anything.

  • Simulate realistic transient lightcurves for Rubin LSST Survey using the latest cadence tables and for ZTF. Or make your own survey. Simulate single transients or populations or simulate a full survey including non-detections and realistic cadences and noise.

  • Redback uses Bilby under the hood for sampling. Can easily switch samplers/likelihoods etc. By default the choice is made depending on the data.

  • Fitting returns a homogenous result object, with functionality to plot fitted lightcurves and the posterior/evidence/credible intervals etc. You can use the result object for hierarchical inference or importance sampling etc.

Advantages of the interface to bilby

We use bilby under the hood for inference, which has many advantages.

  • Easily change samplers, likelihoods, place constraints on priors, etc.

  • Natural interface with gravitational-wave parameter estimation. Enabling multi-messenger analysis with redback used in fitting to the electromagnetic data, and bilby for gravitational-wave parameter estimation.

  • A large developer/user base for core functionality. bilby is adopted by the LIGO-Virgo-Kagra Collaboration and used in all parameter estimation results by the LVK collaboration and in over 500 publications, a testament to its ease of use and robustness.