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Session 69 - Starburst Galaxies.
Display session, Thursday, June 11
Atlas Ballroom,

[69.04] Ultraluminous Starburst Potential in the Antennae Galaxies: NGC 4038/39

Y. Gao, R. A. Gruendl (U. Illinois), K. Y. Lo, S. -W. Lee, C. Y. Hwang (ASIAA, Taiwan)

The total molecular gas mass in the Antennae galaxy systems, the nearest IR-luminous, prototypical galaxy-galaxy merger, has been mistakenly adopted in literature for more than a decade and up to the most current papers, which is, as we show in this poster, about a factor of 5 smaller than the true value. We believe that some interpretations based on this wrong molecular gas mass are therefore incorrect and need modifications accordingly. While starbursts are observed in some extended regions in the Antennae we argue that the intense starbursts might have just been initiated recently. It will undergo through the much stronger ultraluminous starburst phase producing enormous star formation with IR power comparable to the bolometric luminosity of quasars. We present our millimeter CO (measure of the total molecular gas) and HCN (tracer of the much dense molecular gas) line observations and compare with various other observations, such as VLA HI, HST WFPC2, ISO mid-IR, ROSAT HRI, and our own VLA 20cm radio continuum observations, in this on-going merger together with other statistical studies of the IR-luminous mergers to discuss the onset and fate of the starburst. We suggest that, even without the efficient HI-to-H_2 gas phase conversion in the disks and the return of the extended HI gas in the tidal tails onto the merging disks, the pre-existing molecular ISM in the disks might be sufficient for the system to ultimately reach the ultraluminous phase when most of the gas falls into the disk overlap region and the nuclei are almost merged.

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Program listing for Thursday