Gas and Dust in NGC 7469: Submillimeter Imaging and COJ = 3–2

We present sensitive sub-mm imaging of the Seyfert 1 galaxy NGC 7469 at 850$\mu $m and 450 $\mu $m with the Submillimetre Common User Bolometer Array(SCUBA) on the James Clerk Maxwell Telescope (JCMT) and ^{12}CO J=3-2 lineobservations of its central starbursting region. The global dust spectrum, asconstrained by the new set of sub-mm data and available 1.30 mm and IRAS 100$\mu $m, 60 $\mu $m data reveals a dominant warm dust component with atemperature of $\rm T_{\rm d} \sim 35$ K and a global molecular gas-to-dustratio $\rm M(H_2)/M_{\rm d}\sim 600$. Such high values are typical forIR-bright spirals and in order to reconcile them with the significantly lowerratio of ~ 100 obtained for the Milky Way a cold dust reservoir, inconspicuousat FIR wavelengths, is usually postulated. We present evidence that, ratherthan unaccounted cold dust mass, this high ratio suggests an overestimate of$\rm M(H_2)$ from its associated ^{12}CO J=1-0 line luminosity by a factor of ~5 when a Milky Way value for this conversion is used in starburst nucleienvironments.Comment: 25 pages, 3 figures Accepted for publication in the Astrophysical Journa