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Published April 1, 2011 | Published
Journal Article Open

Molecular Gas in Lensed z >2 Quasar Host Galaxies and the Star Formation Law for Galaxies with Luminous Active Galactic Nuclei

Abstract

We report the detection of luminous CO(J = 2→1), CO(J = 3→2), and CO(J = 4→3) emission in the strongly lensed high-redshift quasars B1938+666 (z = 2.059), HE 0230-2130 (z = 2.166), HE 1104-1805 (z = 2.322), and B1359+154 (z = 3.240), using the Combined Array for Research in Millimeter-wave Astronomy. B1938+666 was identified in a "blind" CO redshift search, demonstrating the feasibility of such investigations with millimeter interferometers. These galaxies are lensing-amplified by factors of μ_L ≃ 11-170, and thus allow us to probe the molecular gas in intrinsically fainter galaxies than currently possible without the aid of gravitational lensing. We report lensing-corrected intrinsic CO line luminosities of L'_(CO) = 0.65-21×10^9 K km s^(-1) pc^2, translating to H_2 masses of M(H_2) = 0.52-17 × 10^9 (α_(CO)/0.8) M_☉. To investigate whether or not the active galactic nucleus (AGN) in luminous quasars substantially contributes to L FIR, we study the L'_(CO)-L_(FIR) relation for quasars relative to galaxies without a luminous AGN as a function of redshift. We find no substantial differences between submillimeter galaxies and high-z quasars, but marginal evidence for an excess in L_(FIR) in nearby low-L FIR AGN galaxies. This may suggest that an AGN contribution to L_(FIR) is significant in systems with relatively low gas and dust content, but only minor in the most far-infrared-luminous galaxies (in which L_(FIR) is dominated by star formation).

Additional Information

© 2011 American Astronomical Society. Received 2010 November 24; accepted 2011 January 28; published 2011 March 10. We thank the referee for a helpful and constructive report. D.R. acknowledges support from NASA through Hubble Fellowship grant HST-HF-51235.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. Support for CARMA construction was derived from the G. and B. Moore Foundation, the K. T. and E. L. Norris Foundation, the Associates of the California Institute of Technology, the states of California, Illinois, and Maryland, and the NSF. Ongoing CARMA development and operations are supported by the NSF under a cooperative agreement, and by the CARMA partner universities.

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August 22, 2023
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