[Users] two quick question regarding parameter files and systems of coordinates

Hamilton, Maria babiuc at marshall.edu
Wed Feb 8 15:31:44 CST 2017


Hello,

I have two few quick questions that are intended to facilitate a user-friendly approach to the EinsteinToolkit in order to be used for an undergraduate project. The first question concerns the availability of out-of-the-box parameter files for the evolution of a binary system. Are the parameter files in repos/einsteinexamples/par/ maintained? If not, would it be possible to have up to date parameter files for the evolution of a binary system: bbh and neutron-bh, with the current version of the toolkit?

My second question is about the physical meaning of the coordinate system.
My understanding about units is that you get the physical time in seconds by the formula:
t[s]=t[code]*M_binary*M_sun*G/c^3
x[m]=x[code]*M_binary*M_sun*G/c^2
Will you please confirm or infirm this?
Is this measured in a plain Cartesian coordinate system centered in the center of mass of the system where x=0?
Should t=0 be the time of collision or the initial time?
Is this the only coordinate system used, or there is a different one in the wave zone?

Thank you,
Maria


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