COLDz: Karl G. Jansky Very Large Array Discovery of a Gas-rich Galaxy in COSMOS

Lentati, L.; Wagg, J.; Carilli, C.L.; Riechers, D.; Capak, P.; Walter, F.; Aravena, M.; da Cunha, E.; Hodge, J.A.; Ivison, R.J.; Smail, I.; Sharon, C.; Daddi, E.; Decarli, R.; Dickinson, M.; Sargent, M.; Scoville, N.; Smolčć, V.

doi:10.1088/0004-637x/800/1/67

COLDz: Karl G. Jansky Very Large Array Discovery of a Gas-rich Galaxy in COSMOS

Lentati, L.; Wagg, J.; Carilli, C.L.; Riechers, D.; Capak, P.; Walter, F.; Aravena, M.; da Cunha, E.; Hodge, J.A.; Ivison, R.J.; Smail, I.; Sharon, C.; Daddi, E.; Decarli, R.; Dickinson, M.; Sargent, M.; Scoville, N.; Smolčć, V.

Authors

L. Lentati

J. Wagg

C.L. Carilli

D. Riechers

P. Capak

F. Walter

M. Aravena

E. da Cunha

J.A. Hodge

R.J. Ivison

Professor Ian Smail ian.smail@durham.ac.uk
Emeritus Professor

C. Sharon

E. Daddi

R. Decarli

M. Dickinson

M. Sargent

N. Scoville

V. Smolčć

Abstract

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 arcmin2 region of the COSMOS field. We argue that the broad line (FWHM ~ 570 ± 80 km s–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 phot = 3.2 ± 0.4. The CO J = 1-0 line luminosity is $L^{\prime }_{\rm CO} = (2.2\pm 0.3) \times 10^{10}$ K km s–1 pc2, suggesting a cold molecular gas mass of M gas ~ (2-8) × 1010 M ☉ depending on the assumed value of the molecular gas mass to CO luminosity ratio αCO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L IR = 2.5 × 1012 L ☉ and the star formation rate is ~250 M ☉ yr–1, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114 ± 19 L ☉/(K km s–1 pc2), 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.

Citation

Lentati, L., Wagg, J., Carilli, C., Riechers, D., Capak, P., Walter, F., …Smolčć, V. (2015). COLDz: Karl G. Jansky Very Large Array Discovery of a Gas-rich Galaxy in COSMOS. Astrophysical Journal, 800(1), Article 67. https://doi.org/10.1088/0004-637x/800/1/67

Journal Article Type	Article
Acceptance Date	Dec 1, 2014
Online Publication Date	Feb 10, 2015
Publication Date	Feb 10, 2015
Deposit Date	Feb 16, 2016
Publicly Available Date	Apr 20, 2016
Journal	Astrophysical Journal
Print ISSN	0004-637X
Electronic ISSN	1538-4357
Publisher	American Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	800
Issue	1
Article Number	67
DOI	https://doi.org/10.1088/0004-637x/800/1/67
Related Public URLs	http://adsabs.harvard.edu/abs/2015ApJ...800...67L