title: An intensity map of hydrogen 21-cm emission at redshift z approximately 0.8.
abstract: Observations of 21-cm radio emission by neutral hydrogen at redshifts z approximately 0.5 to approximately 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z approximately 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24. More distant galaxies generally are too faint for individual detections but it is possible to measure the aggregate emission from many unresolved galaxies in the 'cosmic web'. Here we report a three-dimensional 21-cm intensity field at z = 0.53 to 1.12. We then co-add neutral-hydrogen (H i) emission from the volumes surrounding about 10,000 galaxies (from the DEEP2 optical galaxy redshift survey). We detect the aggregate 21-cm glow at a significance of approximately 4sigma.
authors.affiliation: IAA, Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan. tchang@cita.utoronto.ca
authors.forename: Tzu-Ching
authors.initials: TC
authors.lastname: Chang
authors.forename: Ue-Li
authors.initials: UL
authors.lastname: Pen
authors.forename: Kevin
authors.initials: K
authors.lastname: Bandura
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Peterson