Initial Results from the Nobeyama Molecular Gas Observations of Distant Bright Galaxies

TL;DR

This paper reports initial CO observations of high-redshift galaxies using the Nobeyama 45m telescope, demonstrating the instrument's capability to detect molecular gas and determine galaxy redshifts without prior information.

Contribution

First results showcasing the Nobeyama 45m telescope's wide bandwidth spectrometer for detecting molecular gas in distant galaxies and determining their redshifts.

Findings

Detected molecular gas in three high-redshift galaxies.

Derived gas masses around 10^11 solar masses.

Spectrometer enables redshift determination without prior data.

Abstract

We present initial results from the CO survey toward high redshift galaxies using the Nobeyama 45m telescope. Using the new wide bandwidth spectrometer equipped with a two-beam SIS receiver, we have robust new detections of three high redshift (z=1.6-3.4) submillimeter galaxies (SXDF 1100.001, 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 from wide-band submm spectroscopy. The derived molecular gas mass and line widths from Gaussian fits are ~10^11 Msun and 430-530 km/s, which are consistent with previous CO observations of distant submm galaxies and quasars. The spectrometer that allows a maximum of 32 GHz instantaneous bandwidth will provide new science capabilities at the Nobeyama 45m telescope, allowing us to determine redshifts of bright submm selected galaxies without any prior redshift information.