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<p>Dear Roland,</p>
<p>Thanks for your detailed reply. </p>
<p>I learn a lot !</p>
<p>I will consider the proper way to consider these parameters or not to consider them.</p>
<p><br>
</p>
<p>Best regards,</p>
<p>Chia-Hui</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>寄件者:</b> Haas, Roland <rhaas@illinois.edu><br>
<b>寄件日期:</b> 2019年2月13日 下午 09:51:10<br>
<b>收件者:</b> 林家暉<br>
<b>副本:</b> Einstein Toolkit Users<br>
<b>主旨:</b> Re: [Users] parameter output of gallery example</font>
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<div class="PlainText">Hello Chia-Hui,<br>
<br>
> I have a problem about the gallery example of binary neutron star<br>
> (<a href="https://einsteintoolkit.org/gallery/bns/index.html">https://einsteintoolkit.org/gallery/bns/index.html</a>).<br>
> <br>
> Is it possible to evolve and output some parameters like entropy ,<br>
> temperature and electron fraction ? Is so , how should I modify the<br>
> parameter file (NsNsToHMNS.par) ?<br>
Unfortunately the gallery example is not set up to do that. It uses a<br>
simple gamma-law equation of state that does not support entropy,<br>
temperature or electron fraction.<br>
<br>
The closest thing that exists to temperature is the specific internal<br>
energy that appears in the equation of state and you could try and<br>
separate it into a "cold" piece due to eg Fermi energy and a thermal<br>
piece.<br>
<br>
There are right now no public examples in the Einstein Toolkit on how<br>
to evolve a BNS using a finite temperature EOS that would support<br>
entropy and electron fraction.<br>
<br>
If you wanted to do so, you would have to modify the parfile to use a<br>
tabulated equation of state to a tabulated EOS:<br>
<br>
GRHydro::GRHydro_eos_table = nuc_eos<br>
<br>
set options for the root finding required for the hot eos, eg.<br>
<br>
GRHydro::GRHydro_eos_hot_eps_fix = yes<br>
<br>
as well as specifying temperature and electron fraction for the hot<br>
atmosphere in the <br>
<br>
grhydro::grhydro_hot_atmo_temp<br>
grhydro::grhydro_hot_atmo_Y_e<br>
<br>
parameters and range of allowed electron fractions in grhydro_y_e_min/max.<br>
<br>
You will have to tell HydroBase that initial date for temperature, entropy and y_e are provided by setting the respective HydroBase::initial_XXX parameters and setting the HydroBase::XXX_evolution_method parameters to "GRHdyro". Obviously you will have to provide
initial data. LORENE provides some datasets for tabulated EOS (<a href=""></a>ftp://octane.obspm.fr/BinaryNS/GR/Realistic/ though none matches a cold slice of a finite difference EOS and given a cold, beta-equilibrium slice one could use its tabulated EOS
capability to create ID) that may serve though I have never used them myself. You will also have to extend the Meudon_BNS_ID reader in Cactus to support the extra variables (and likely use LORENE2 instead of LORENE).<br>
<br>
You can find tabulated EOS on the stellarcollapse.org website <a href="https://stellarcollapse.org/microphysics">
https://stellarcollapse.org/microphysics</a> which can be used with GRHydro. Please see that site for references to acknowledge when using them.<br>
<br>
Note that without a neutrino radiation code like ZelmaniLeak or ZelmaniM1 (both on stellarcollapse.org
<a href="https://stellarcollapse.org/Zelmani">https://stellarcollapse.org/Zelmani</a>) the electron fraction is simply advected along. Setting up the neutrino codes is not something I have experience in.<br>
<br>
Also please note that I have not myself evolved BNS using a finite<br>
temperature EOS in Cactus and that the description above is a best<br>
effort based on my reading of param.ccl.<br>
<br>
Yours,<br>
Roland<br>
<br>
-- <br>
My email is as private as my paper mail. I therefore support encrypting<br>
and signing email messages. Get my PGP key from <a href="http://keys.gnupg.net">http://keys.gnupg.net</a>.<br>
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