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AtomDB project (www.atomdb.org)
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pyatomdb.apec.do_brems does not use all arguments? #43

Open eblur opened 2 years ago

eblur commented 2 years ago

Hi, we are considering using the bremsstrahlung model -- pyatomdb.apec.do_brems -- as a way to model bremsstrahlung emission more generally.

However, we are noticing a few weird things about this functino. First, the Z parameter (Zint in the documentation) is never used in the function.

Additionally, the docstring says that the abund value must be between 0 and 1, but what if we need to calculate bremsstrahlung emission from a super-Solar abundance?

Out of curiousity, what method would you recommend for using pyatomdb to model bremsstrahlung emission from plasmas hotter than 10^9 K?

jagophile commented 2 years ago

Hi Lia, There is definitely some cruft in there. These functions were ported from early versions and the interfaces have redundancies/ bad documentation. I will leave this open until I remember to clean this up.

As you note, Z is not needed. The abundance can actually be anything, including greater that 1, and should represent the combination of the ion fraction and the elemental abundance (or, as we have implemented it, just set it to 1 in do_brems and multiply these afterwards). Note this is the actual numerical abundance, not the relative to solar values.

As for the high temperature, use the relativistic model. In addition, you should also use the electron-electron brems, calc_ee_brems(E, T, N) which really starts to kick in at these at temperatures, and add the two.

Hope this helps!

randallksmith commented 2 years ago

Also, if you use calc_ee_brems, please cite Xiaohong Cui's paper (Cui+2019, ApJ, 887, 182) - she did a really nice job and could use the citations.

Thanks! Randall

On Thu, Oct 6, 2022 at 3:29 PM Adam Foster @.***> wrote:

Hi Lia, There is definitely some cruft in there. These functions were ported from early versions and the interfaces have redundancies/ bad documentation. I will leave this open until I remember to clean this up.

As you note, Z is not needed. The abundance can actually be anything, including greater that 1, and should represent the combination of the ion fraction and the elemental abundance (or, as we have implemented it, just set it to 1 in do_brems and multiply these afterwards). Note this is the actual numerical abundance, not the relative to solar values.

As for the high temperature, use the relativistic model. In addition, you should also use the electron-electron brems, calc_ee_brems(E, T, N) which really starts to kick in at these at temperatures, and add the two.

Hope this helps!

— Reply to this email directly, view it on GitHub https://github.com/AtomDB/pyatomdb/issues/43#issuecomment-1270581733, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABIFEMC6EPK5P3IA3EX3GFDWB4SARANCNFSM6AAAAAAQ6WGEWU . You are receiving this because you are subscribed to this thread.Message ID: @.***>