Millimetre/submillimetre-wave emission-line searches for high-redshift galaxies
The redshifted spectral line radiation emitted from both atomic fine-structure and molecular rotational transitions in the interstellar medium (ISM) of high-redshift galaxies can be detected in the centimetre, millimetre and submillimetre wavebands. Here we predict the counts of galaxies detectable in an array of molecular and atomic lines. This calculation requires a reasonable knowledge of both the surface density of these galaxies on the sky, and the physical conditions in their ISM. The surface density is constrained using the results of submillimetre-wave continuum surveys. Follow-up OVRO Millimeter Array observations of two of the galaxies detected in the dust continuum have provided direct measurements of CO rotational line emission at redshifts of 2.56 and 2.81. Based on these direct high-redshift observations and on models of the ISM that are constrained by observations of low-redshift ultraluminous infrared galaxies, we predict the surface density of line-emitting galaxies as a function of line flux density and observing frequency. We incorporate the sensitivities and mapping speeds of existing and future millimetre/submillimetre-wave telescopes and spectrographs, and so assess the prospects for blank-field surveys to detect this line emission from gas-rich high-redshift galaxies.
Additional Information© 2000 RAS. Accepted 1999 November 11. Received 1999 November 10; in original form 1999 March 24. The results in this paper are based on the properties of the SCUBA lens survey galaxies detected at the Owens Valley Millimeter Array in collaboration with Aaron Evans and Min Yun. The core of the SCUBA lens survey was carried out by Ian Smail, Rob Ivison, AWB and Jean-Paul Kneib. We thank the referee, Paul van der Werf, for his careful reading of the manuscript and valuable comments, and also Jackie Davidson, Kate Isaak, Rob Ivison, Richard Hills, Brett Kornfeld, Malcolm Longair, Phil Lubin, Kate Quirk, John Richer and Gordon Stacey for helpful conversations and comments. AWB - the Raymond & Beverly Sackler Foundation Research Fellow at the IoA, Cambridge - gratefully acknowledges generous support from the Raymond & Beverly Sackler Foundation as part of the Deep Sky Initiative programme at the IoA. AWB also thanks the Caltech AY visitors program for support while this work was conducted.
Published - BLAmnras00.pdf