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Published August 21, 2012 | Published
Journal Article Open

The JCMT Nearby Galaxies Legacy Survey – VIII. CO data and the L_(CO(3-2))–L_(FIR) correlation in the SINGS sample

Abstract

The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey (NGLS) comprises an H i-selected sample of 155 galaxies spanning all morphological types with distances less than 25 Mpc. We describe the scientific goals of the survey, the sample selection and the observing strategy. We also present an atlas and analysis of the CO J=3 - 2 maps for the 47 galaxies in the NGLS which are also part of the Spitzer Infrared Nearby Galaxies Survey. We find a wide range of molecular gas mass fractions in the galaxies in this sample and explore the correlation of the far-infrared luminosity, which traces star formation, with the CO luminosity, which traces the molecular gas mass. By comparing the NGLS data with merging galaxies at low and high redshift, which have also been observed in the CO J=3 - 2 line, we show that the correlation of far-infrared and CO luminosity shows a significant trend with luminosity. This trend is consistent with a molecular gas depletion time which is more than an order of magnitude faster in the merger galaxies than in nearby normal galaxies. We also find a strong correlation of the L_(FIR)/L_(CO(3-2)) ratio with the atomic-to-molecular gas mass ratio. This correlation suggests that some of the far-infrared emission originates from dust associated with atomic gas and that its contribution is particularly important in galaxies where most of the gas is in the atomic phase.

Additional Information

© 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Accepted 2012 June 7. Received 2012 May 23; in original form 2012 February 6. Article first published online: 23 Jul. 2012. The James Clerk Maxwell Telescope is operated by The Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the Netherlands Organisation for Scientific Research and the National Research Council of Canada. The research of PB, PC, S. Courteau, MF, MH, JI,ER, ES, KS, TW and CDW is supported by grants from NSERC (Canada). AU has been supported through a Post Doctoral Research Assistantship from the UK Science and Technology Facilities Council. Travel support for BEW and TW was supplied by the National Research Council (Canada). We acknowledge the usage of the HyperLeda data base (http://leda.univ-lyon1.fr). CV received support from the ALMA-CONICYT Fund for the Development of Chilean Astronomy (Project 31090013) and from the Center of Excellence in Astrophysics and Associated Technologies (PBF 06). This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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Created:
September 14, 2023
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October 23, 2023