Wolfgang Tichy

Recipes for eccentricity reduction with Sgrid and BAM

There are now 2 versions of neutron star initial data in Sgrid. The old one is called BNSdata and the new one DNSdata. The new DNSdata can create higher mass and spin configurations, and may also run faster. So it should be preferred.

There are also 2 ways to reduce eccentricity. The first way is described in EccRed_v1.md for use with the old BNSdata. The second way is described in EccRed_v2.md for DNSdata. Additional details about the 2 ways are in Ecc-Red-Notes.txt. For either way we need scripts to fit the orbital separation to the sinusoidal curve d(t)=S0+A0*t+0.5*A1*t^2-(B/omega)cos(omega*t+phi). For the 1st way we have EccRed.py (see e-based eccentricity reduction) and for the 2nd way we use EccRed_noForceBal.py (see Omega-based eccentricity reduction). All scripts can be found at https://github.com/sgridsource/EccRed.

To check that the fit was successful, one needs to plot the fit and the original data. This can be done with tgraph which is at https://github.com/wofti/tgraph.

Parameter files for Sgrid

Several sample parfiles are in sgrid/src/Projects/DNSdata/ParFiles . Not all of these are for binaries and thus useful for eccentricity reduction. The parfiles are described in sgrid/src/Projects/DNSdata/ParFiles/Note.txt .

Running Sgrid and BAM

Sgrid and also BAM can be started with the submitjob script found at https://github.com/wofti/WTscripts. For slurm you also need slurm_mpirun_script.