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| galprop gas files https://galprop.stanford.edu/forum/viewtopic.php?f=5&t=42 |
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| Author: | tibaldo [ Thu May 24, 2007 6:27 am ] |
| Post subject: | galprop gas files |
Which quantity is described in the input file rbands_co4.fits? Is it the number density of hydrogen MOLECULES or the number density of PROTONS in form of molecules? |
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| Author: | strong [ Fri May 25, 2007 12:14 am ] |
| Post subject: | rbands co |
it's the integrated Tco dv, in units of K km s-1 which has to be converted to molecular hydrogen column density using the famous Xco factor (e.g. as given in the galdef file). |
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| Author: | tibaldo [ Fri May 25, 2007 12:36 am ] |
| Post subject: | galprop gas files |
I found some misleading information, both in the file header, where you wrote as unit cm^-2, and in the GALPROP v.50 manual (September 6, 2006), where (page 4 bottom) you can read "the H2 gas number density is defined in the form of table ... and the conversion factor is taken as X= ..." |
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| Author: | strong [ Fri May 25, 2007 12:58 am ] |
| Post subject: | H2 and rbands |
there are two things: 1 the galprop internally modelled H_2 which is indeed as described in the manual on page 4, using a fixed Xco=1.9E20. This is used for cosmic-ray propagation but not for gamma-rays 2 the Wco rings in rbands, which are used to compute the gamma-rays. You are apparently right about the error in the header, I informed Seth Digel ! Clearly 1 & 2 are not consistent: we know this and are working on a new version where they will be consistent. However the effect is not great. But consistency is very desirable of course. |
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| Author: | digel [ Sat May 26, 2007 10:30 pm ] |
| Post subject: | BUNIT keyword values in rbands FITS files |
Luigi is correct that the units are incorrectly stated in the header of rbands_co4.fits. They are K km s^-1, as Andy says. It was just a mistake to list the units as '10E20 cm-2'. This came about because I used the same BUNIT string for the H I rings (rbands_hi7.fits). 10E20 cm-2 now looks ambiguous (or wrong) to me for the H I rings. I meant 10^20 cm^-2. I'll fix the headers of both files in their next update. Thanks, Luigi, for pointing out the error. |
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