[Users] weird waveform for binary black holes system

[Shawn Rosofsky]

Hi Qingwen,

There is nothing unusual about your current waveform that I can see.  The
weirdness comes from the fact that the waveform is incomplete and hence
does not decay to zero at the final time.  This messes up the integration
from psi4 to h and causes the strange bouncing around that you currently
see.  If you were to compare the raw psi4 data of the two waveforms, I'd
expect they would agree quite closely. In general, you should probably
refrain from looking at the strain data until your simulation has run to
completion.

This issue is quite common with neutron star waveforms which don't always
go to zero at the final time.  It can be resolved by tapering the end of
the psi4 data to ensure that it does decay to zero at the final time.

Best,
Shawn

On Tue, Sep 18, 2018, 8:43 AM Qingwen Wang <qwang at perimeterinstitute.ca>
wrote:

> Hi all,
>
> I am using Einstein toolkit to simulate binary black hole merger, and I
> was trying to repeat https://einsteintoolkit.org/gallery/bbh/index.html.
> But I end up with a weird waveform like(I did not finish all the
> simulation, but it has started to look weird of the peak around t=300)
> [image: image.png]
> rather than(the right one )
>
> [image: image.png]
> I am planning to run it again for a longer time, it would be really
> helpful if anyone knows what's wrong with my last running so that I can
> edit it before redoing it. Thank you for your time.
>
> Regards,
> Qingwen
> _______________________________________________
> Users mailing list
> Users at einsteintoolkit.org
> http://lists.einsteintoolkit.org/mailman/listinfo/users
>
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