<div dir="ltr">Francisco<div><br></div><div>Without hydrodynamics, nothing fundamental sets the mass scale. If you assume that c = G = 1, then there is a rescaling freedom for M, the black hole mass. Apart from this, it is up to the designer of the parameter file what they call M. I think that the ADM mass is a good choice, but others might use a different convention. In practice, one examines the black hole masses and the ADM mass in a simulation, which is then returned in terms of the grid spacing, which is related to the time step size, thus you see what M is used in this particular case.</div><div><br></div><div>For example, in <<a href="http://einsteintoolkit.org/gallery/bbh/index.html">http://einsteintoolkit.org/gallery/bbh/index.html</a>> I assume that M_ADM = 1, but I don't know whether this is taken from the initial conditions or whether this is measured after the initial junk radiation has left.</div><div><br></div><div>I hope my answer isn't too trivial.</div><div><br></div><div>-erik</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Apr 12, 2017 at 3:30 PM, Francisco Guzman <span dir="ltr"><<a href="mailto:guzman@ifm.umich.mx" target="_blank">guzman@ifm.umich.mx</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-family:arial,helvetica,sans-serif;font-size:12pt;color:#000000"><div><br></div><div>Hi all,</div><div><br></div><div>Could you guys please point me to the reference where I can see how units are defined for a binary black hole simulation?</div><div><br></div><div>(Or possibly simply answer):</div><div><br></div><div>I just want to know what the units of space and time (M) are. </div><div>What is M? is it the ADM mass at initial time? the addition of the two black hole masses?... or so...</div><div><br></div><div>I apologize in advance in case my question is terribly dummy. </div><div><br></div><div>Thanks,</div><div>Francisco</div></div></div><br>______________________________<wbr>_________________<br>
Users mailing list<br>
<a href="mailto:Users@einsteintoolkit.org">Users@einsteintoolkit.org</a><br>
<a href="http://lists.einsteintoolkit.org/mailman/listinfo/users" rel="noreferrer" target="_blank">http://lists.einsteintoolkit.<wbr>org/mailman/listinfo/users</a><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Erik Schnetter <<a href="mailto:schnetter@cct.lsu.edu" target="_blank">schnetter@cct.lsu.edu</a>><br><a href="http://www.perimeterinstitute.ca/personal/eschnetter/" target="_blank">http://www.perimeterinstitute.ca/personal/eschnetter/</a></div>
</div>