This figure shows two images of quasars from a sample of 20 relatively nearby quasars examined by a team of European astronomers using two of the most powerful astronomical facilities available, the NASA/ESA Hubble Space Telescope and the ESO Very Large Telescope (VLT) at Cerro Paranal.
The quasar on the left, HE0450-2958 (distance to its centre, about 5000 million light-years) does not have a massive 'host' galaxy. The quasar HE1239-2426 on the right (1500 million light-years away), has a normal 'host' galaxy which displays large spiral arms. Although HE1239-2426 is much closer than HE0450-2958, the host galaxy of the latter would still be clearly visible if it was as bright as the one of HE1239-2426.
Also seen in the image to the left (above the quasar) is a strongly disturbed galaxy, showing all the signs of a recent collision. The VLT observations show it to be forming stars at a frantic rate. Below the quasar a foreground star is seen.
The images were taken with the Advanced Camera for Surveys on board the NASA/ESA Hubble Space Telescope and have been scaled to exhibit the same linear scale.