Gas and dust in NGC 7469:: Submillimeter imaging and CO J=3-2

We present sensitive submillimeter imaging of the Seyfert 1 galaxy NGC 7469 at 850 and 450 mu m with the Submillimeter Common User Bolometer Array on the James Clerk Maxwell Telescope and (12)CO J = 3-2 line observations of its central starbursting region. The global dust spectrum, as constrained by the new set of submillimeter data and available 1.30 mm and IRAS 100 and 60 mu m data, reveals a dominant warm dust component with a temperature of T(d) similar to 35 K and a global molecular gas-to-dust ratio M(H(2))/M(d) similar to 600. Including the atomic gas component yields a total gas-to-dust ratio of similar to 830. Such high values are typical for IR-bright spiral galaxies, and in order to reconcile them with the significantly lower ratio of similar to 100 obtained for the Milky Way, a cold dust reservoir, inconspicuous at far-infrared wavelengths, is usually postulated However, while there is good evidence for the presence of cold gas/dust in NGC 7469 beyond its central region, our 450 mu m map and available interferometric (12)CO J = 1-0 maps show the bright submillimeter/CO emission confined in the inner similar to 2.5 kpc, where a high (12)CO (J = 3-2)/(J = 1-0) ratio (similar to 0.85-1.0) is measured. This is consistent with molecular gas at T(kin) greater than or similar to 30 K, suggesting that the bulk of the interstellar medium in the starburst center of NGC 7469 is warm. Nevertheless, the corresponding total gas-to-dust ratio there remains high, of the order of similar to 500. We argue that, rather than unaccounted cold dust mass, this high ratio suggests an overestimate of M(H(2)) from its associated (12)CO J = 1-0 line luminosity by a factor of similar to 5 when a Milky Way value for this conversion is used. Finally, the diffuse cold gas and dust that is the likely source of the observed faint extended 450 mu m and (12)CO J = 1-0 emission has an estimated total gas-to-dust ratio of similar to 50-160, closer to the Galactic value.