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[61.19] FUSE Survey of Interstellar Molecular Hydrogen toward 40 High-Latitude AGN

K. Gillmon, J.M. Shull (Univ. Colorado, CASA), J. Tumlinson (Univ. Chicago)

We present the results of a Far Ultraviolet Spectroscopic Explorer (FUSE) survey of interstellar molecular hydrogen in the Galactic halo along 40 sightlines to background AGN at Galactic latitudes b > 10 degrees (and less than -10 degrees). FUSE spectra of 60% of the observed (AGN) sources exhibit Galactic interstellar absorption lines from the H₂ Lyman and Werner bands between 912 and 1120 Å, corresponding to a column density threshold, log N(H₂) > 14.2. We report N(H₂) for each sightline, together with column densities N(J) for individual rotation levels J = 0 - 4 in the ground electronic and vibrational state. We supplement these results with N(H I) from a combination of 21 cm and Lyman-beta measurements. We use these column densities to derive the molecular fraction, rotational temperature, T₀₁, and rotational excitation conditions for each sightline. We also look for correlations of H₂ with infrared cirrus clouds near these halo sightlines.

This work was supported by the FUSE Mission, with support from NASA Contract NAGS5-32985 and a sub-contract to the University of Colorado at Boulder.

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Bulletin of the American Astronomical Society, 36 #2
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