Resonance Averaged Photoionization Cross Sections for Astrophysical Models

Details Resonance Averaged Photoionization Cross Sections for Astrophysical Models Resonance Averaged Photoionization Cross Sections for Astrophysical Models

1997-12-03

arxiv.org/abs/astro-ph/9712037v1

Astronomy and Astrophysics

Astrophysics

23 pages, 5 embedded figures (eps), submitted ApJS

Scientific paper

10.1086/313132

We present ground state photoionization cross sections of atoms and ions averaged over resonance structures for photoionization modeling of astrophysical sources. The detailed cross sections calculated in the close-coupling approximation using the R-matrix method, with resonances delineated at thousands of energies, are taken from the Opacity Project database TOPbase and the Iron Project, including new data for the low ionization stages of iron Fe I--V. The resonance-averaged cross sections are obtained by convolving the detailed cross sections with a Gaussian distribution over the autoionizing resonances. This procedure is expected to minimize errors in the derived ionization rates that could result from small uncertainties in computed positions of resonances, while preserving the overall resonant contribution to the cross sections in the important near threshold regions. The detailed photoionization cross sections at low photon energies are complemented by new relativistic distorted-wave calculations for Z<= 12, and from central-field calculations for Z>12 at high energies, including inner-shell ionization. The effective cross sections are then represented by a small number of points that can be readily interpolated linearly for practical applications; a Fortran subroutine and data are available. The present numerically averaged cross sections are compared with analytic fits that do not accurately represent the effective cross sections in regions dominated by resonances.

Affiliated with

Also associated with

No associations

Rating

Resonance Averaged Photoionization Cross Sections for Astrophysical Models does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Resonance Averaged Photoionization Cross Sections for Astrophysical Models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Resonance Averaged Photoionization Cross Sections for Astrophysical Models will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-99335