Alternative title: Markov Chain Monte Carlo Multi-Colour Magnetar Calculations with the MOSFiT Code (MCMCMCMCMC).

Fit to the light curve of PTF12dam using MOSFiT

Earlier this summer (it’s been so busy!) we published the first results from our new multi-purpose light curve code. The Modular Open Source Fitter for Transients (MOSFiT) was written by James Guillochon and myself (with help from many others) so that we could model the evolution of supernovae and other transients using Bayesian (MCMC) analysis, and fit these models to all of the multicolour data available so as not to lose any temperature information. Even better – it downloads the data straight from the Open Supernova Catalog for easy use, and is fully open source with discrete modules so users can plug and play with different models, or include their own. We feel like this should be a really useful tool for the whole community, and encourage everyone to try it out and help us to improve it! James is working on a paper to describe the code and its usage, but here I’d like to flag up some of the cool results from our first project with MOSFiT.

Of course we started with my favourite topic: understanding the power source and progenitor stars of superluminous supernovae (SLSNe). We decided to fit magnetar-powered models to every published SLSN with a good light curve. This was 38 events – the most SLSNe yet in a single study. We already knew that magnetars could reproduce the luminosity, but we found that they also match the colours of SLSNe, even though these can vary significantly from one event to the next! We identified relations between ejected mass, kinetic energy, spin period and magnetic field that seem to define when a supernova can become superluminous. Most interestingly to me, we found that the magnetars have to be spinning extremely fast (1-5 ms rotation periods) and that these stars must have been born with over 20 times the mass of the Sun. This can help to explain why these explosions are so rare! You can find out much more detail by checking out the paper here.