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

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

Research output: Contribution to journalArticlepeer-review

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 infrareddetected galaxy with a photometric redshift estimate of zphot = 3.2 0.4. The CO J = 1-0 line luminosity is L CO = (2.2 0.3) x 1010 Kkms-1 pc2, suggesting a cold molecular gas mass of Mgas (2-8) x 1010M depending on the assumed value of the molecular gas mass to CO luminosity ratio aCO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is LIR = 2.5 x 1012 L and the star formation rate is 250M yr-1, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is 114 19L /(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.

Original languageEnglish
Article number67
Number of pages5
JournalAstrophysical Journal
Volume800
Issue number1
DOIs
Publication statusPublished - 10 Feb 2015

Keywords

  • galaxies: high-redshift
  • galaxies: star formation
  • radio lines: galaxies
  • STAR-FORMING GALAXIES
  • HUBBLE DEEP FIELD
  • SUBMILLIMETER-SELECTED GALAXIES
  • FAR-INFRARED PROPERTIES
  • MOLECULAR LINE SCAN
  • LYMAN BREAK GALAXY
  • SIMILAR-TO 3
  • ULTRALUMINOUS GALAXIES
  • EXTRAGALACTIC SURVEY
  • CONVERSION FACTOR

Cite this