COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe

摘要: We report the first detailed measurement of shape CO luminosity function at high redshift, based on >320 hr NSF's Karl G. Jansky Very Large Array (VLA) observations over an area ~60 arcmin^2 taken as part Luminosity Density High Redshift (COLDz) survey. COLDz "blindly" selects galaxies their cold gas content through CO(J = 1 → 0) emission z ~ 2–3 and 2 1) 5–7 down to a limit log(L’_(CO)/K km s^(−1) pc^2) ≃ 9.5. find that characteristic bright end are substantially higher than predicted by semi-analytical models, but consistent with empirical estimates infrared 2. also present currently most reliable cosmic density in early epochs, i.e., history universe, determined large volume ~375,000 Mpc3. Our measurements agreement increase from 0 2–3, followed possible decline toward 5–7. These findings recent surveys higher-J line measurements, upon which improves terms statistical uncertainties probing ~50–100 times larger areas reliability total mass low-J lines accessible VLA. results thus appear suggest star formation rate follows increased molecular its peak about 10 billion years ago, earliest epochs is likely related lower overall amount (as traced CO) bound after Big Bang.