source + nebula along the line of sight
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Andrés Gúrpide
Dec 5, 2023, 3:20:16 PM12/5/23
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Hi everyone!
I'm looking at a source through its photoionized nebula and I'm trying to compare the pycloudy output with some optical emission lines I have. For the sake of simplicity assume the nebula is radiation bounded, although we do not really see it's extent since we are observing it along the line of sight.
My question is whether I need to integrate the emissivities along the line of sight (for instance if I assume I'm observing through one pixel of my detector, something like (outputmod.get_emis(line) * outputmod.drff * pixel_size_pc**2).sum()) or whether I need to take the values of the lines at the last radius of the nebula (outputmod.get_emis(line)[-1] * outputmod.drff[-1] * pixel_size_pc**2).
From the manual:The emissivity is obtained with the save lines emissivity command, described in Part 1 of this document. This gives the net emission, with units erg cm −3 s −1 , emitted by a unit volume of gas and emergent from the cloud surface. The total emission is the integral of the emissivity. An integral over radius will give the line intensity 4πJ while an integral over volume will give the luminosity
it would appear that the former approach is the valid one, but emergent from the cloud surface confuses me. Am I understanding this correctly?
Also, would it be integrating up to a certain r<r_out the equivalent of making the nebula matter-bounded? i.e. the equivalent of running Cloudy with a lower outer radius? or at least very approximately?
Another approach would be to consider the net transmitted spectrum (i.e. get_cont_y("trans"), which could be compared directly to my data. Would you agree with this approach?
Any guidance/thoughts on this would be appreciated! Thank you!
I'm looking at a source through its photoionized nebula and I'm trying to compare the pycloudy output with some optical emission lines I have. For the sake of simplicity assume the nebula is radiation bounded, although we do not really see it's extent since we are observing it along the line of sight.
My question is whether I need to integrate the emissivities along the line of sight (for instance if I assume I'm observing through one pixel of my detector, something like (outputmod.get_emis(line) * outputmod.drff * pixel_size_pc**2).sum()) or whether I need to take the values of the lines at the last radius of the nebula (outputmod.get_emis(line)[-1] * outputmod.drff[-1] * pixel_size_pc**2).
From the manual:The emissivity is obtained with the save lines emissivity command, described in Part 1 of this document. This gives the net emission, with units erg cm −3 s −1 , emitted by a unit volume of gas and emergent from the cloud surface. The total emission is the integral of the emissivity. An integral over radius will give the line intensity 4πJ while an integral over volume will give the luminosity
it would appear that the former approach is the valid one, but emergent from the cloud surface confuses me. Am I understanding this correctly?
Also, would it be integrating up to a certain r<r_out the equivalent of making the nebula matter-bounded? i.e. the equivalent of running Cloudy with a lower outer radius? or at least very approximately?
Another approach would be to consider the net transmitted spectrum (i.e. get_cont_y("trans"), which could be compared directly to my data. Would you agree with this approach?
Any guidance/thoughts on this would be appreciated! Thank you!
Christophe Morisset
Dec 11, 2023, 5:12:51 AM12/11/23
to pyCloudy
Hi Andres,
All the questions you are writing are actually about Cloudy, not really about pyCloudy (which is only a python wrapper to Cloudy). The best would be to ask to the Cloudy discussion group: https://cloudyastrophysics.groups.io/g/Main
Best regards,
Christophe
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