ar X iv : a st ro - p h / 04 09 55 9 v 1 2 3 Se p 20 04 CI emission in Ultra Luminous Infrared Galaxies as a molecular gas mass tracer

Abstract

We present new sensitive wide-band measurements of the fine structure line P1 → P0 (J=1–0, 492 GHz) of neutral atomic carbon (CI) in the two typical Ultra Luminous Infrared Galaxies NGC 6240 and Arp 220. We then use them along with several other CI measurements in similar objects found in the literature to estimate their global molecular gas content under the assumption of a full CI-H2 concomitance. We find excellent agreement between the H2 gas mass estimated with this method and the standard methods using CO. This may provide a new way to measure H2 gas mass in galaxies, and one which may be very valuable in ULIRGs since in such systems the bright CO emission is known to systematically overestimate the gas mass while their CO emission (an often-used alternative) is usually very weak. At redshifts z ≥ 1 the CI J=1-0 line shifts to much more favorable atmospheric windows and can become a viable alternative tracer of the H2 gas fueling starburst events in the distant Universe. Subject headings: galaxies: starbursts – galaxies: individual (NGC 6240, Arp 220) – ISM: atoms – ISM: molecules also Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK

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Cite this paper

@inproceedings{Papadopoulos2004arXI, title={ar X iv : a st ro - p h / 04 09 55 9 v 1 2 3 Se p 20 04 CI emission in Ultra Luminous Infrared Galaxies as a molecular gas mass tracer}, author={Padeli P. Papadopoulos and Thomas R. Greve}, year={2004} }