Skip to main content
eScholarship
Open Access Publications from the University of California

UCLA

UCLA Previously Published Works bannerUCLA

A search for molecular gas toward a BzK -Selected star-forming galaxy at z = 2.044

Abstract

We present a search for CO (3-2) emission in SDF-26821, a BzK-selected star-forming galaxy (sBzK) at z = 2.044, using the 45-m telescope of the Nobeyama Radio Observatory and the Nobeyama Millimeter Array. We did not detect significant emission, and derived the 2σ limits: CO luminosity of L′co < 3.1 × 1010K kms-1 pc -2, ratio of far-infrared luminosity to CO luminosity of L FIR/L′co > 57 L⊙ (K km s-1 pc2)-1, and molecular gas mass of MH2 < 2.5 × 1010 M⊙, assuming a velocity width of 200 kms -1 and a CO-to-H2 conversion factor of αco = 0.8 M⊙ (K km s-1 pc2) -1. The ratio LFIR/L′CO, a measure of the star-formation efficiency (SFE), is comparable to, or higher than, the two z ∼ 1.5 sBzKs detected in CO (2-1) previously, suggesting that sBzKs can have a wide range of SFEs. Comparisons of far-infrared luminosity, gas mass, and stellar mass among the sBzKs suggest that SDF-26821 is at an earlier stage of forming stars with a similar SFE and/or more efficiently forming stars than the two z ∼ 1.5 sBzKs. The higher SFEs and specific star-formation rates of the sBzKs compared to local spirals are indicative of a difference in the star-formation modes between these systems, suggesting that sBzKs are not just scaled-up versions of local spirals. © 2009. Astronomocal Society of Japan.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View