Raymond vs. AstroBEAR - Hydrogen Ionization and Recombination

Ionization (H —> HII)

I went through the Raymond shock code and figured out how it calculates the collisional ionization rate for H. I then plotted this (CION, black) as a function of temperature alongside the table that we use in AstroBEAR (AB Rate, red). In AstroBEAR, the units we assume on these values are cm3/s.

The two curves match pretty well which is great. Unfortunately, this also means that the discrepancy between the codes is elsewhere and still unknown. If we have the units wrong in AstroBEAR, then we are doing the scaling wrong which occurs after this ionization rate calculation. Also, the Raymond shock code has photoionization, but AstroBEAR does not.

I also made a plot of the ratio of the two rates. Even though they are on the same order of magnitude, you can see that the Raymond rate is often 10% - 60% higher than the AstroBEAR rate within the temperature range that is relevant to my simulations. I'm not sure if this difference is significant or not.


Recombination (HII —> H)

I did the same thing for HII recombination. This time, I put the y-axis on a log scale to make the difference more visible.

The two rates only differ at very high temperatures. My simulations do not use such high temperatures so this is fine.

Attachments (3)

Download all attachments as: .zip

Comments

No comments.