[Mesa-users] Changing reaction rate issu in PPISN

Fri Jan 21 07:17:44 UTC 2022

Hi Mathieu,

"Regarding running PPISN at low-Z: I would look at how sharp the core edges
are in these models. Once wind-mass loss becomes too small, the cores
become sharper and it is hard for pulses to get through them (as I found in
models with no-winds at finite Z). If you really want low-Z model an idea
could be add some small extra mixing (D_mix = 1d-2 for example) to smooth
the edges a bit without messing up the stars too much. N.B: I have not
tested this myself."

Thanks for this, I was not aware this could be an issue and am interested
in testing it. I looked for D_mix in controls_defalts but couldn't find a
verbatim control with that name. What's the control I should be looking for?

I am using MESA-r12778.

Cheers,

Jeremy

On Thu, Jan 20, 2022 at 9:52 AM Mathieu Renzo via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi Vaishnav and Harshda,
>
> I believe you want to set num_special_rate_factors=1 in your inlist.
>
> The exact setup to reproduce Farmer et al. results is available on zenodo:
> https://zenodo.org/record/3346593
> <https://urldefense.com/v3/__https://zenodo.org/record/3346593__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqrTgj-eA$>
> and https://zenodo.org/record/3559859
> <https://urldefense.com/v3/__https://zenodo.org/record/3559859__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLq6mpQiP0$>
> (and I believe
> https://ui.adsabs.harvard.edu/abs/2022ApJ...924...39M/abstract
> <https://urldefense.com/v3/__https://ui.adsabs.harvard.edu/abs/2022ApJ...924...39M/abstract__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqweviSa0$>
> successfully used these).
>
> Regarding running PPISN at low-Z: I would look at how sharp the core edges
> are in these models. Once wind-mass loss becomes too small, the cores
> become sharper and it is hard for pulses to get through them (as I found in
> models with no-winds at finite Z). If you really want low-Z model an idea
> could be add some small extra mixing (D_mix = 1d-2 for example) to smooth
> the edges a bit without messing up the stars too much. N.B: I have not
> tested this myself.
>
> Hope this helps!
> Mathieu
>
> On 1/20/22 2:17 PM, Vaishnav Rao via Mesa-users wrote:
>
> Dear MESA users,
>
> We have been playing around with the PPISN test suite for the past year in
> an attempt to understand and reproduce the black hole mass gap. We were
> facing difficulties in incorporating custom reaction rates for the C12-O16
> reaction in our test suite.
>
> We have been attempting to reproduce the plots of the effect of CO
> reaction rates on the final BH mass as in Farmer et al., 2019
> <https://urldefense.com/v3/__https://arxiv.org/abs/1910.12874__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqZ-kHYE4$>
>  and Farmer et al., 2020
> <https://urldefense.com/v3/__https://arxiv.org/abs/2006.06678__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqqCEqLDI$>
>  . Using the reaction rates from the files of the latter, we tried to run
> a modified test suite with recommended settings (which had already run for
> the default rates for us before). However, upon comparing the final BH
> masses for 0 sigma and -1 sigma rate tables, there was no major difference,
> even though there is an expected difference of 8M in the final BH masses.
> Clearly the lines
>
> num_special_rate_factors=0
> reaction_for_special_factor(1)='r_c12_ag_o16'
> special_rate_factor(1)=1.0d0 ! Used for linear scaling of rates
>
> rate_tables_dir='rates/c12alpha/rate_tables-1s’
>
> which specify the path to the modified rate tables do not seem to be
> having any major effect on the simulations.
>
> Our simulations are for metallicities of 1d-3 (in accordance with Farmer
> et al., 2019
> <https://urldefense.com/v3/__https://arxiv.org/abs/1910.12874__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqZ-kHYE4$>).
> We chose this metallicity because our simulations for 1d-5 ( as in Farmer
> et al., 2020
> <https://urldefense.com/v3/__https://arxiv.org/abs/2006.06678__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqqCEqLDI$>) faced
> multiple convergence issues (mostly ‘hydro_failed’ or too many
> retries). According to the other posts we saw on the MESA mailing list
> archives, many others too faced convergence issues of this sort for such
> low metallicities. We are not sure whether using the same rate tables for
> different metallicities is correct.
>
> Our inlist, run_star_extras, and rate tables (zip file) have been attached
> for reference. Any advice on solving this issue would be appreciated.
>
> Software details:
> MESA version: r12778
> SDK version: March 25, 2020
> OS: Cluster, 64-bit Linux
>
> Thanking you in advance,
> Vaishnav V. Rao & Harshda Saxena
> Department of Physics
> Indian Institute of Technology Bombay
>
>
>
>
>
>
>
>
> _______________________________________________mesa-users at lists.mesastar.orghttps://lists.mesastar.org/mailman/listinfo/mesa-users <https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqrlXpcfY$>
>
>
> --
> Mathieu Renzo
> <https://urldefense.com/v3/__https://users.flatironinstitute.org/*mrenzo/__;fg!!IBzWLUs!ABtxVxvf_FCkApSkViSy473uCSgoV0h6ZsUFt3-meFhtMdAI8BR-D0E9ouLqHIltOU0$>
> Flatiron Research Fellow
> Center for Computational Astrophysics
> Columbia University
> _______________________________________________
> mesa-users at lists.mesastar.org
>
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>
>

-- 
Jeremy Sakstein (He/Him/His)
Assistant Professor of Theoretical Physics
Department of Physics & Astronomy
University of Hawaiʻi at Mānoa
Watanabe Hall
2505 Correa Road
Honolulu, HI, 96822, USA
http://www.jeremysakstein.com
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