[Mesa-users] Changing reaction rate issu in PPISN

[Mathieu Renzo]

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
and https://zenodo.org/record/3559859 (and I believe 
https://ui.adsabs.harvard.edu/abs/2022ApJ...924...39M/abstract 
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://arxiv.org/abs/1910.12874> and Farmer et al., 2020 
> <https://arxiv.org/abs/2006.06678> . 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 
> withFarmer et al., 2019 <https://arxiv.org/abs/1910.12874>). We chose 
> this metallicity because our simulations for 1d-5 ( as inFarmer et 
> al., 2020 <https://arxiv.org/abs/2006.06678>) 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.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>

-- 
Mathieu Renzo <https://users.flatironinstitute.org/~mrenzo/>
Flatiron Research Fellow
Center for Computational Astrophysics
Columbia University
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