AAS 201st Meeting, January, 2003
Session 116. Galaxies - Activating
Poster, Thursday, January 9, 2003, 9:20am-4:00pm, Exhibit Hall AB

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[116.08] A Search for O VI Emission in the M82 Starburst Superwind

C. G. Hoopes, T. M. Heckman, D. K. Strickland (JHU), J. C. Howk (CASS/UCSD)

Galactic scale superwinds from starbursts have an important impact on the evolution of galaxies and the intergalactic medium. However, the full extent of their influence is still in question, due to the lack of information on the ``coronal'' phase in the wind. Emission from this 105 - 106 K gas may dominate the cooling in the superwind, and thereby determine the evolution of the wind and its ability to deposit mass and energy into the intergalactic medium. We have used the Far Ultraviolet Spectroscopic Explorer (FUSE) to search for O VI emission from coronal gas in the starburst superwind in M82. Four locations within the wind, chosen on the basis of their X-ray flux, were observed with FUSE. No O VI emission was detected in any of the pointings. We have used optical spectra and X-ray observations of the FUSE pointings to determine the effects of extinction, and find that amount of obscuration is too small to hide significant O VI emission. The FUSE observations limit the amount of cooling to less than that of the X-ray emission, which is itself insignificant to the energy balance of the wind (Strickland & Stevens 2000, MNRAS, 314, 511). Since so little energy is lost to radiation, it is likely that the wind retains enough energy to escape from the galaxy potential. We discuss some possible explanations for the absence of coronal-temperature gas, and the implications of the lack of cooling on the evolution of starburst superwinds.

This research was supported by NASA grant NAG5-11945.

The author(s) of this abstract have provided an email address for comments about the abstract: choopes@pha.jhu.edu

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