Sampling initial populations

The process to generate a synthetic binary population, is similar to the process to evolve a single/multiple binaries by hand: first generate an initial population, then evolve it with the Evolve class.

An initialized binary population consists of a collection of binary systems with assigned primary and secondary masses, orbital periods, eccentricities, metallicities, and star formation histories. These parameters are randomly sampled from observationally motivated distribution functions.

In COSMIC, the initial sample is done through an initial binary sampler which works with the InitialBinaryTable class. There are two samplers available:

1. independent : initialize binaries with independent parameter distributions for the primary mass, mass ratio, eccentricity, separation, and binary fraction

2. multidim : initialize binaries with multidimensional parameter distributions according to Moe & Di Stefano 2017

We consider both cases in the guides below.

• Independent distributions
• Multidimensional distributions

You can also use COSMIC to sample the initial conditions for a Globular Cluster (GC) using the ClusterMonteCarlo (CMC) software package. Check out the guide below for more information.

• ClusterMonteCarlo Sampling

Tip

The initial binary population that is generated with these sampling methods can be quickly and easily evolved using the Evolve class. This is demonstrated in this guide.