A Search for Molecular Gas toward a BzK-Selected Star-Forming Galaxy at z=2.044

作者：Hatsukade Bunyo^*; Iono Daisuke; Motohara Kentaro; Nakanishi Kouichiro; Hayashi Masao; Shimasaku Kazuhiro; Nagao Tohru; Tamura Yoichi; Malkan Matthew A; Ly Chun; Kohno Kotaro

来源：Publications of the Astronomical Society of Japan, 2009, 61(3): 487-491.

DOI：10.1093/pasj/61.3.487

• cosmology: observations
• galaxies: evolution
• galaxies: formation
• galaxies: high-redshift
• galaxies: individual (SDF-26821)
• galaxies: ISM
• galaxies: starburst

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 2 did not detect significant ernission, and derived the 2 sigma limits: CO luminosity of L'(CO) < 3.1 x 10(10) K km s(-1) pc(-2), ratio of far-infrared luminosity to CO luminosity of L(FIR)/L'(CO) > 57 L(circle dot) (K km s(-1) pc(2))(-1), and molecular gas mass of M(H2) < 2.5 x 10(10) M(circle dot), assuming a velocity width of 200 km s(-1) and a CO-to-H(2) conversion factor of alpha(CO) = 0.8 M(circle dot) (K km s(-1) pc(2))(-1). The ratio L(FIR)/L'(CO) a measure of the star-formation efficiency (SFE), is comparable to, or higher than, the two z similar to 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 similar to 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.

• 出版日期2009
• 单位中国科学院国家天文台