This figure shows two Hubble images of quasars from a sample of 20 relatively nearby quasars examined by a team of European astronomers with two of the most powerful astronomical facilities available, NASA's Hubble Space Telescope and the European Southern Observatory's (ESO) Very Large Telescope (VLT) at Cerro Paranal.
The team confidently concludes that the quasar on the left, HE0450-2958 (in the center, distance about 5 billion light-years) does not have a massive host galaxy. The quasar HE1239-2426 to the right (at a distance of 1.5 billion light-years), 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 perfectly visible if it was as bright as that of HE1239-2426.
The lack of a prominent host galaxy around a very bright quasar (HE0450-2958) suggests a rare case of a collision between a seemingly normal spiral galaxy and an exotic object harboring a very massive black hole.
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. A foreground star is seen below the quasar.
The two images have been scaled to exhibit the same linear scale.
The images were taken with Hubble's Advanced Camera for Surveys in October 2004.