COLDz: KARL G. JANSKY VERY LARGE ARRAY DISCOVERY OF A GAS-RICH GALAXY IN COSMOS

Journal Article · Tue Feb 10 00:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/800/1/67· OSTI ID:22364191

Lentati, L. ^[1]; Wagg, J. ^[2]; Carilli, C. L. ^[3]; Riechers, D.; Sharon, C. ^[4]; Capak, P.; Scoville, N. ^[5]; Walter, F.; Da Cunha, E.; Decarli, R. ^[6]; Aravena, M. ^[7]; Hodge, J. A. ^[8]; Ivison, R. J. ^[9]; Smail, I. ^[10]; Daddi, E. ^[11]; Dickinson, M. ^[12]; Sargent, M. ^[13]

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1. Astrophysics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
2. Square Kilometre Array Organisation, Jodrell Bank Observatory, Lower Withington, Macclesfield, Cheshire SK11 9DL (United Kingdom)
3. National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
4. Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)
5. California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
6. Max-Planck Institute for Astronomy, D-69117 Heidelberg (Germany)
7. Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago (Chile)
8. National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
9. European Southern Observatory, Karl-Schwarzschild Strasse, D-85748 Garching bei Munchen (Germany)
10. Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
11. CEA-Saclay, Service d'Astrophysique, F-91191 Gif-sur-Yvette (France)
12. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
13. Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH (United Kingdom)

The broad spectral bandwidth at millimeter and centimeter wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48 through the detection of CO J = 1-0 line emission in the COLDz survey and through a sensitive, Ka-band (31-39 GHz) VLA survey of a 6.5 arcmin{sup 2} region of the COSMOS field. We argue that the broad line (FWHM ∼ 570 ± 80 km s{sup –1}) is most likely to be CO J = 1-0 at z = 2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z {sub phot} = 3.2 ± 0.4. The CO J = 1-0 line luminosity is L{sub CO}{sup ′}=(2.2±0.3)×10{sup 10} K km s{sup –1} pc{sup 2}, suggesting a cold molecular gas mass of M {sub gas} ∼ (2-8) × 10{sup 10} M {sub ☉} depending on the assumed value of the molecular gas mass to CO luminosity ratio α{sub CO}. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L {sub IR} = 2.5 × 10{sup 12} L {sub ☉} and the star formation rate is ∼250 M {sub ☉} yr{sup –1}, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ∼114 ± 19 L {sub ☉}/(K km s{sup –1} pc{sup 2}), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future.

• OSTI ID: 22364191
• Journal Information: Astrophysical Journal, Vol. 800, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON MONOXIDE
COSMIC DUST
DETECTION
ENERGY SPECTRA
GALAXIES
GHZ RANGE
LUMINOSITY
MASS
PHOTON EMISSION
RED SHIFT
STARS
UNIVERSE
VISIBLE RADIATION