COLDz: A High Space Density of Massive Dusty Starburst Galaxies ~1 Billion Years after the Big Bang

摘要: We report the detection of CO($J$=2$\to$1) emission from three massive dusty starburst galaxies at $z$$>$5 through molecular line scans in NSF's Karl G. Jansky Very Large Array (VLA) CO Luminosity Density High Redshift (COLDz) survey. Redshifts for two sources, HDF 850.1 ($z$=5.183) and AzTEC-3 ($z$=5.298), were previously known. revise a previous redshift estimate third source GN10 ($z$=5.303), which we have independently confirmed detections $J$=1$\to$0, 5$\to$4, 6$\to$5, [CII] 158 $\mu$m with VLA NOrthern Extended Milllimeter (NOEMA). find that currently sources COLDz are "optically dark", them dust-obscured $z$$>$5. Given our survey area $\sim$60 arcmin$^2$, results appear to imply $\sim$6-55 times higher space density such distant systems within first billion years after Big Bang than thought. At least these show star-formation rate surface densities consistent so-called "maximum" starbursts, but significant differences excitation between them. This result may suggest different fractions gas reservoirs located dense, star-forming nuclear regions - more extended sizes compared dust continuum [CII]-to-far-infrared luminosity ratios those lower excitation. thus substantial variations conditions star formation typically temperatures $\sim$57%$\pm$25% warmer starbursts $z$=2-3 due their enhanced activity.