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Issue with the G0 in save pdf

Brandt Gaches
 
Edited

Dear all,

EDIT: my auto correct corrected "pdr" to pdf. The title should say "in save pdr".

I have been trying to run a benchmark test to compare Cloudy with a different code I have been developing. The test problem is an X-ray source (XRB) with a spectrum L ~ E^-2 between 1 - 10 keV. For the chemistry to not have too many issues, I have included an ISM radiation field using the "table ISM -6". I know this is not quite correct, since the table ISM should be used for an external flux and with the power law it is included in the "source" emission. However, the ISM flux is set to be very small. One issue that I have seen is that, while the incident spectrum looks ok, G0 seems to increase through the cloud for a range of column densities (plot attached), rather than decrease through the cloud. I'm not sure if this is due to some bug in the "save pdr" code, or if the UV flux is being enhanced due to the radiation transfer effects with emission of other species in the UV. Is there a good way to double check/verify this? I could not see an option for saving the spectrum at every point.

Thanks,
Brandt

Gary Ferland
 

I am not sure where you are getting the G0 from the code, but a likely source of additional line will be the lines that emit in the gas.  Lya is included in the G0 band and is a likely source of additional light.  We compute the Lya intensity self consistently including production by secondary electrons and destruction by background opacities such as dust.  use the SAVE EMITTED CONTINUUM command to have a look at emission within the cloud.

On Wed, Jun 24, 2020 at 1:56 PM Brandt Gaches <gaches@...> wrote:
Dear all,

I have been trying to run a benchmark test to compare Cloudy with a different code I have been developing. The test problem is an X-ray source (XRB) with a spectrum L ~ E^-2 between 1 - 10 keV. For the chemistry to not have too many issues, I have included an ISM radiation field using the "table ISM -6". I know this is not quite correct, since the table ISM should be used for an external flux and with the power law it is included in the "source" emission. However, the ISM flux is set to be very small. One issue that I have seen is that, while the incident spectrum looks ok, G0 seems to increase through the cloud for a range of column densities (plot attached), rather than decrease through the cloud. I'm not sure if this is due to some bug in the "save pdr" code, or if the UV flux is being enhanced due to the radiation transfer effects with emission of other species in the UV. Is there a good way to double check/verify this? I could not see an option for saving the spectrum at every point.

Thanks,
Brandt



--
Gary J. Ferland
Physics, Univ of Kentucky
Lexington KY 40506 USA
Tel: 859 257-8795
https://pa.as.uky.edu/users/gary