The findings, which are backed by another paper in the same issue by David Hughes and colleagues of the University of Edinburgh, are forcing scientists to reassess theories about how and when stars are born. Earlier surveys, largely restricted to visible galaxies, suggested that star formation peaked when the universe was roughly three quarters of its current age. The pioneering deep exposures conducted by groups in Hawaii, the U.K. and Canada have shown the importance of studying galaxies at large look-back times at wavelengths other than simply the traditional optical and infrared regions. This radical new bolomoter array, mounted on top of the 15-meter JCMT telescope in Mauna Kea, offers a glimpse at primordial galaxies. In fairness, such far-off star systems are difficult to detect.
Dust absorbs visible starlight and reradiates it at much longer wavelengths.
In nearby dusty galaxies, these longer wavelengths still fall within the far-infrared range, at one end of the visible spectrum. As a result, these sources are described as submillimeter galaxies. A bolometer measures the heat emitted from small dust particles in the submillimeter sky, much as a camera measures the light radiated by nearer sources. Cowie and colleagues performed deep surveys of two blank regions of the sky, Lockman Hole and the well-studied field SSA13. Hughes et al.