A rotating giant cloud around an infant galaxy

This composite picture shows the galaxy 1243+036. Its redshift has been measured as 3.6; this corresponds to a "look-back" time of about 90 percent of the age of the Universe (or a distance of about 12,000 - 15,000 million light years). We therefore observe it, as it was when the age of the Universe was only 10 percent of what it is now.

To the left is an artist's rendering of the enormous gas cloud that was discovered in 1995 by a team of astronomers from Leiden University by means of spectroscopic observations with the EMMI instrument at the ESO 3.5-metre New Technology Telescope (NTT) in Chile.

1243+036 is embedded in the cloud which is probably a relic of the process that formed this infant galaxy (here indicated by a dark oval at the centre and the contours seen in the right-hand part of the picture). The observations have also shown that this cloud, as seen from the Earth, is elongated in the NW-SE direction, and one interpretation is that it has a disk-like shape, as shown here. Moreover, they demonstrate that the cloud rotates in such a way that the NW edge (upper right) moves away from us and the SE edge approaches us, relative to the centre. The largest extension of the cloud (20 arcseconds in the sky) is almost 500,000 light years.

The right part of the picture is a composite, false-colour image that was obtained by the Leiden astronomers with the same telescope. It shows the isophotes (contours of equal brightness) of the innermost part of the gas cloud and was taken through a filter centred at the redshifted wavelength of the Lyman-alpha emission line from hydrogen atoms. The yellow contours show radio emission from narrow collimated jets of electrons produced deep inside the nucleus of the galaxy; the radio data came from NRAO's Very Large Array in the United States.

North is up and East is to the left on this picture.