The researchers began their observations by first analyzing these early galaxies with the Keck Observatory.
Lin Yan, a staff scientist at IPAC and coauthor on the paper, says that their results are also especially important because they represent typical early galaxies. "Galaxies come in different sizes. Earlier observations could only spot the largest or the brightest galaxies, and those tend to be very special—they actually appear very rarely in the population," she says. "Our findings tell you something about a typical galaxy in that early epoch, so they're results can be observed as a whole, not just as special cases."
Yan says that their ability to analyze the properties of these and earlier galaxies will only expand with ALMA's newly completed capabilities. During the study, ALMA was operating with only a portion of its antennas, 20 at the time; the capabilities to see and analyze distant galaxies will be further improved now that the array is complete with 66 antennas, Yan adds.
The findings are published in a paper titled, "Systematically low dust content and high [CII] emission in galaxies at redshifts 5-6." The work was supported by funds from NASA and the European Union's Seventh Framework Program. Nick Scoville, the Francis L. Moseley Professor of Astronomy, was an additional coauthor on this paper. In addition to Keck, Hubble, and ALMA data, observations from the Spitzer Space Telescope were used to measure the stellar mass and age of the galaxies in this study. Coauthors and collaborators from other institutions include C. Carilli, G. Jones, C.M. Casey, D. Riechers, K. Sheth, C.M. Corollo, O. Ilbert, A. Karim, O. LeFevre, S. Lilly, and V. Smolcic.