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Paper: The Star Formation Law in Terms of Dense Gas: A Model of Star Formation in Galaxies
Volume: 375, From Z-Machines to ALMA: (Sub)Millimeter Spectroscopy of Galaxies
Page: 291
Authors: Wu, J.; Evans, N.; Gao, Y.; Solomon, P.; Shirley, Y.; Vanden Bout P.
Abstract: Observations have revealed prodigious amounts of star formation in starburst galaxies as traced by dust and molecular emission, even at large redshifts. Recent work shows that for both nearby spiral galaxies and distant starbursts, the global star formation rate, as indicated by the infrared luminosity, has a tight and almost linear correlation with the amount of dense gas as traced by the luminosity of HCN. Our surveys of Galactic dense cores in HCN(10) and HCN(32) emission show that this correlation continues to a much smaller scale, with nearly the same ratio of infrared luminosity to HCN luminosity found over 78 orders of magnitude in LFIR, with a lower cutoff around 104.5 LSolar in infrared luminosity. This correlation suggests a power law index N for the Schimidt law of unity, different from those derived from observations tracing less dense gas like CO. The correlation implies that we may understand distant star formation in terms of the known properties of local star-forming regions. We propose a model in which the basic unit of star formation is a dense core, similar to those studied in our Galaxy; this model may explain both the correlation and the luminosity cutoff.
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