[Mesa-users] Changing reaction rate issu in PPISN

[Jeremy Sakstein]

Hi Vaishnav,

I used the r_C12_ag_O16 reaction rates (just the deBoer ones) from Farmer
et al., 2020
<https://urldefense.com/v3/__https://arxiv.org/abs/2006.06678__;!!IBzWLUs!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgsOPThirY$>
in
MESA-r12778 and found good agreement with the results published there (not
perfect of course because different MESA versions were used). My results
are shown in figure 1 bottom left here: 2104.02685
<https://arxiv.org/abs/2104.02685>.

I'm attaching a minimal working directory that should be able to help you.
By default, it is set up to use the de Boer (2017) median rate but you can
change rate_tables_dir='rate_tables' to 'rate_plus' or 'rate_minus' to
change rates.

I didn't use any special scaling rates so I am unable to help with that. If
I understand you correctly, you want to use the tabulated rates, in which
case what I have attached should be sufficient.

Cheers,

Jeremy



On Thu, Jan 20, 2022 at 9:18 AM Vaishnav Rao via Mesa-users <
mesa-users at lists.mesastar.org> 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!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgs4-rIaA0$>
>  and Farmer et al., 2020
> <https://urldefense.com/v3/__https://arxiv.org/abs/2006.06678__;!!IBzWLUs!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgsOPThirY$>
>  . 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!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgs4-rIaA0$>).
> We chose this metallicity because our simulations for 1d-5 ( as in Farmer
> et al., 2020
> <https://urldefense.com/v3/__https://arxiv.org/abs/2006.06678__;!!IBzWLUs!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgsOPThirY$>) 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://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IBzWLUs!C_xngBzq8lKUvGhFPX00SOK75TgsxCkSlINDtn27mUOwrHJy12HNcwgJpRgsAK4zoyY$
>
>

-- 
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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