November 5, 2010

New method reveals gravitationally lensed galaxies in Herschel-ATLAS first survey

Astronomers using early data from one of the largest projects to be undertaken with the ESA Herschel Space Observatory have demonstrated that virtually all bright sub-millimetre galaxies in the distant Universe are subject to gravitational lensing, which amplifies their flux thus easing their detection and characterisation. Analysis of less than three per cent of the entire Herschel-ATLAS survey, which probes the distant and hidden Universe, yielded a first sample of five lensed galaxies and paves the way for the compilation, in the near future, of a rich catalogue of distant, star-forming and dust-obscured galaxies. The results are reported in the 5 November 2010 issue of Science.

More details, on the ESA website

First area of sky viewed as part of the Herschel-ATLAS survey. © Herschel – ESA
The main image shows the first area of sky viewed as part of the Herschel-ATLAS survey. It is around 4 degrees across - 8 times the width of the Full Moon - and located in the constellation of Hydra. There are over 6000 galaxies present in this image, some seen as they were billions of years ago, and almost all so far away that they are seen by Herschel as a single point of light. Also visible, as wispy structures draped across the image, are diffuse clouds of dust in our own Galaxy. This image makes up around 1/30th of the total area which will be observed by Herschel-ATLAS, in which astronomers should eventually find around 250 000 galaxies. The five insets, measuring 14x14 arcminutes, show enlarged views of the five distant galaxies whose images are being gravitationally lensed by foreground galaxies (unseen by Herschel). The distant galaxies are not only very bright, but also very red in colour in this image, showing that they are brighter at the longer wavelengths measured by the SPIRE instrument.
© Herschel – ESA