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
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@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@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users
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@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@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@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users
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