Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-25T16:02:27.288Z Has data issue: false hasContentIssue false
  • English
  • Français

Modeling the ISM: Molecular Gas, Ionizing Radiation, and Numerical Simulations

Published online by Cambridge University Press:  25 May 2016

Joel N. Bregman
Joel N. Bregman*
Affiliation:
Dept. of Astronomy, Univ. of Michigan, Ann Arbor, MI 48109, USA

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Three different topics regarding the ISM in the Magellanic Clouds are discussed. First, we examine how the Magellanic Stream can be used as a tracer of the ionizing radiation leaking out of Galaxy and the Magellanic Clouds. We show that the radiation reaching the Magellanic Stream is less than 1% of the ionizing radiation produced by Galactic 0 and B stars. Since about 14% of the ionizing radiation from these stars is required to ionize the Reynolds layer, which is within 1 kpc of the disk, most of this radiation must be absorbed before reaching the Stream.

Second, we examine the reliability of using CO as a tracer of H2 in regions of low or modest column densities (not giant molecular cloud complexes). For our Galaxy, the usual CO to H2 conversion factor overlooks a considerable amount of H2 and the evidence suggests that this may be true in the LMC as well. Finally, we present numerical hydrodynamical calculations of the interstellar medium in disk galaxies for a region of size 2 kpc along the plane and 15 kpc out of the plane. The simulations reveal a rich structure of low density hot regions separated by cold dense material, with the resulting position velocity diagrams being qualitatively similar to the recent HI studies of the LMC. A number of other aspects of these simulations are discussed also.

Type
Part 2. Interstellar Medium
Information
Symposium - International Astronomical Union , Volume 190: New Views of the Magellanic Clouds , 1999 , pp. 84 - 92
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Arabadjis, J.S., & Bregman, J.N. 1999, ApJ, 514, 607 Google Scholar
Bland-Hawthorn, J., & Maloney, P.R. 1997, PASA, 14, 59.Google Scholar
Bregman, J.N., & Harrington, J.P. 1986, ApJ, 309, 833.Google Scholar
de Boer, K.S., & Savage, B.D. 1980, ApJ, 238, 86.Google Scholar
Chu, Y.-H., Wakker, B.P., Mac Low, M.-M., & García-Segura, G. 1994, AJ, 108, 1696.Google Scholar
Hartmann, D., Magnani, L., & Thaddeus, P. 1998, ApJ, 492, 205.Google Scholar
Israel, F.P., Maloney, P.R., Geis, N., Herrmann, F., Madden, S.C., Poglitsch, A., & Stacey, G.J. 1996, ApJ, 465, 738.CrossRefGoogle Scholar
Kim, S., Staveley-Smith, L., Dopita, M.A., Freeman, K.C., Sault, R.J., Kesteven, M.J., & McConnell, D. 1998, ApJ, 503, 674.Google Scholar
Kulkarni, V.P., & Fall, S.M. 1995, ApJ, 453, 65.Google Scholar
Lucas, R., & Liszt, H. 1996, A&A, 307, 237.Google Scholar
McConnell, D., McCulloch, P.M., Hamilton, P.A., Ables, J.G., Hall, P.J., Jacka, C.E., & Hunt, A.J. 1991, MNRAS, 249, 654.Google Scholar
Reynolds, R.J. 1991, in: The Interstellar Disk-Halo Connection in Galaxies , ed. Bloemen, H. (Kluwer: Dordrecht), p. 67.Google Scholar
Rosen, A., & Bregman, J.N. 1995, ApJ, 440, 634.CrossRefGoogle Scholar
Rosen, A., Bregman, J.N., & Kelson, D.D. 1996, ApJ, 470, 839.CrossRefGoogle Scholar
Savage, B.D. Bohlin, R.C., Drake, J.F., & Budich, W. 1977, ApJ, 216, 291.Google Scholar
Snowden, S.L., & Petre, R. 1994, ApJ, 436, L123.Google Scholar
Taylor, J.H., & Cordes, J.M. 1993, ApJ, 411, 674.CrossRefGoogle Scholar
van Dishoeck, E.F., & Black, J.H. 1988, ApJ, 334, 771.Google Scholar
Wakker, B., Howk, J.C., Chu, Y-H., Bomans, D., & Points, S.D. 1998, ApJ, 499, L87.Google Scholar
Weiner, B.J., & Williams, T.B. 1996, AJ, 111, 1156.CrossRefGoogle Scholar