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P. M. Solomon (Physics and Astronomy, SUNY, StonyBrook), P. A. Vanden Bout, R. Maddalena (NRAO)
We report observations of strong HCN (1-0) emission from the z = 2.2 infrared-luminous quasar IRAS F10214+4724 using the Green Bank Telescope (GBT). HCN emission associated with the cores of giant molecular clouds is a signpost of dense, star-forming molecular gas. HCN has a critical density for excitation of n \approx 105 cm-3 , 300 times higher than that of CO. An important question is whether the far-infrared luminosity from high redshift quasars is due to the active galactic nucleus (AGN) or a huge starburst occurring in a disk around the AGN. After allowing for magnification by an intervening lens, the HCN line luminosity and mass of dense molecular gas is higher in F10214+4724 than in local ultra-luminous infrared galaxies (ULIRGs) like Arp 220, strongly supporting a star formation origin for the 1013 L\odot of far-infrared luminosity. The ratio of far infrared to line luminosities, L(FIR)/Lī(HCN), indicates that the star formation rate per solar mass of dense gas is similar to that of local ULIRGs and only slightly higher than that of normal spiral galaxies. A very large fraction of all molecular gas in this galaxy is dense gas. This is the essential condition for a starburst. A starburst of this magnitude is a major event in the formation of a galaxy and may be responsible for forming the galactic bulge. We will present a detailed comparison of the dense gas in F10214+4724 with that in local universe galaxies and in the Cloverleaf, another high redshift quasar with HCN emission. These observations demonstrate the power of the GBT for the detection of broad , weak spectral lines.
The author(s) of this abstract have provided an email address for comments about the abstract: psolomon@astro.sunysb.edu
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.