[Users] weird waveform for binary black holes system

[Qingwen Wang]

Thank you Shawn for the clarification. I didn’t realize the integration
part.  Always focused on the psi4 before. That’s really helpful.

Regards,
Qingwen

Shawn Rosofsky <shawnrosofsky at gmail.com>于2018年9月18日 周二上午10:02写道：

> 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
>>
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