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Molecular Cloud Structure in the Magellanic Clouds: CO-to-H2 Conversion Factor

Published online by Cambridge University Press:  25 May 2016

Soojong Pak  and
D. T. Jaffe
Soojong Pak
Affiliation:
Astronomy Department, Seoul National University, Kwanak-Gu, Seoul 151-742, Republic of Korea
D. T. Jaffe
Affiliation:
Astronomy Department, University of Texas at Austin, Austin, TX 78712, USA

Extract

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In the Milky Way, the 12CO J = 1 → 0 line traces the molecular gas content. The conversion factor, XGAL, between the H2 column density, N(H2), and the velocity integrated intensity of CO, I(CO), has been measured via the virial theorem or via γ-ray emission (Solomon et al. 1987; Bloemen et al. 1986; Digel et al. 1997; and references therein).

How can we apply XGAL to other galaxies where the metallicities are different from that of our Galaxy? The metallicity dependence of the conversion factor has been an issue. Cohen et al. (1988), Wilson (1995), and Arimoto, Sofue, & Tsujimoto (1996) argued that the value of X increases as the metallicity of the individual galaxy decreases. In contrast, Taylor, Kobulnicky, & Skillman (1996) showed that some low abundance galaxies have lower X.

Type
Part 2. Interstellar Medium
Information
Symposium - International Astronomical Union , Volume 190: New Views of the Magellanic Clouds , 1999 , pp. 114 - 115
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

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