Density Bounded H II Regions: Ionization of the Diffuse Interstellar and Intergalactic Media

Zurita, A.; Rozas, M.; Beckman, J. E.
Bibliographical reference

"Astrophysical Plasmas: Codes, Models, and Observations, Proceedings of the conference held in Mexico City, October 25-29, 1999, Eds. Jane Arthur, Nancy Brickhouse, and José Franco, Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias), Volume 9, p. 290-291 POSTSCRIPT: http://www.astrosmo.unam.mx/rmaa/APCM/PSGZ/sapcm_zurita.ps.gz"

Advertised on:
5
2000
Number of authors
3
IAC number of authors
0
Citations
1
Refereed citations
1
Description
We present a study of the diffuse ionized gas (DIG) for a sample of nearby spiral galaxies using Hα images, after constructing their H II region catalogues. The integrated Hα emission of the DIG accounts for between 25% to 60% of the total Hα of the galaxy and a high ionizing photon flux is necessary to keep this gas ionized. We suggest that Lyman photons leaking from the most luminous H II regions are the prime source of the ionization of the DIG; they are more than enough to ionize the measured DIG in the model in which H II regions with luminosity in Hα greater than LStr=1038.6 erg sme are density bounded. We go on to show that this model can quantify the ionization observed in the skins of the high velocity clouds well above the plane of our Galaxy and predicts the ionization of the intergalactic medium.