Multidimensional distributionsΒΆ
COSMIC implements multidimensionally distributed initial binaries according to Moe & Di Stefano 2017. The python code used in COSMIC to create this sample was written by Mads Sorenson, and is based on the IDL codes written to accompany Moe & Di Stefano 2017.
The multidimensional initial binary data is sampled in COSMIC as follows:
In [1]: from cosmic.sample.initialbinarytable import InitialBinaryTable
In [2]: from cosmic.sample.sampler import multidim
Tip
The multidimensional sampler arguments can be found here get_multidim_sampler() or by using the multidimensional sampler help call (help(multidim.get_multidim_sampler))
The random seed is used to reproduce your initial sample, since there are several stochastic processes involved in the muldimensional sample. As in the independent sampler, the final_kstar1 and final_kstar2 inputs are lists containing the kstar types that the evolved population should contain.
The multidimensional sample is generated as follows:
In [3]: InitialBinaries, mass_singles, mass_binaries, n_singles, n_binaries = InitialBinaryTable.sampler('multidim', final_kstar1=[11], final_kstar2=[11], rand_seed=2, nproc=1, SF_start=13700.0, SF_duration=0.0, met=0.02, size=10)
In [4]: print(InitialBinaries)
kstar_1 kstar_2 mass_1 mass_2 ... bhspin_1 bhspin_2 tphys binfrac
0 1.0 1.0 1.279531 1.177286 ... 0.0 0.0 0.0 0.421378
1 1.0 1.0 1.821109 0.932680 ... 0.0 0.0 0.0 0.472138
2 1.0 1.0 7.008791 3.125255 ... 0.0 0.0 0.0 0.818042
3 1.0 1.0 1.311346 1.250257 ... 0.0 0.0 0.0 0.426309
4 1.0 1.0 1.039924 0.821354 ... 0.0 0.0 0.0 0.408716
.. ... ... ... ... ... ... ... ... ...
101 1.0 15.0 0.832261 0.000000 ... 0.0 0.0 0.0 1.000000
102 0.0 15.0 0.292364 0.000000 ... 0.0 0.0 0.0 1.000000
103 0.0 15.0 0.095102 0.000000 ... 0.0 0.0 0.0 1.000000
104 0.0 15.0 0.214237 0.000000 ... 0.0 0.0 0.0 1.000000
105 0.0 15.0 0.519613 0.000000 ... 0.0 0.0 0.0 1.000000
[106 rows x 38 columns]
Note
NOTE that in the multidimensional case, the binary fraction is a parameter in the sample. This results in the size of the initial binary data matching the size provided to the sampler. As in the independent sampling case, we keep track of the total sampled mass of singles and binaries as well as the total number of single and binary stars to scale the simulated population to astrophysical populations.
Note
NOTE that you can also keep singles for the multidim sampelr as well. As with the independent sampler, the singles will be added onto the end of the InitialBinaryTable where kstar_1 will host the singles, kstar_2 will be filled with 15s only, and all orbital properties (e.g. porb or ecc) will be indicated with -1.