Initial Results from Nobeyama Molecular Gas Observations of Distant Bright Galaxies

We present initial results from the CO survey toward high-redshift galaxies using the Nobeyama 45 m telescope. Using a new wide bandwidth spectrometer equipped with a two-beam SIS receiver, we have obtained three new detections of high-redshift (z = 1.6-3.4) submillimeter galaxies (SXDF 1100.001/HXMM02, SDP9, and SDP17), one tentative detection (SDSS J160705+533558), and one non-detection (COSMOS-AzTEC1). The galaxies observed during the commissioning phase are sources with known spectroscopic redshifts from previous optical or wide-band submillimeter spectroscopy. The derived molecular gas mass and line widths from Gaussian fits are ∼10¹¹ M_⊙ and 430-530 km s^-1, respectively, which are consistent with previous CO observations of distant submillimeter galaxies and quasars. The spectrometer, which realizes a maximum of 32 GHz instantaneous bandwidth, will provide new science capabilities at the Nobeyama 45 m telescope, allowing us to determine redshifts of bright submillimeter selected galaxies without any prior redshift information.