ISO observes cosmic IR background galaxies

Two dozen distant galaxies that are undergoing a process of intense evolution - either merging to larger ones or reaching their final shape - have been detected by a team of French astronomers using ESA's Infrared Space Observatory (ISO). These are the first individual objects know to contribute their energy to the Cosmic Infrared Background, a radiation that fills the entire Universe. The newly-found galaxies are indeed like the 'pattern' in this cosmic wallpaper. The oval-shaped image at top-left is a map of the infrared sky obtained by the earlier IRAS satellite. It shows in red the emission from objects in our own Galaxy; this acts like a curtain making it difficult for astronomers to see through. For this observation, ISO was pointed at a region of the southern hemisphere called the Marano Fields, which is especially clean of emission from foreground sources. The new population of galaxies now identified emit so faintly that astronomers could only detect them by using the ISOPHOT spectrophotometer ISO, the best and most sensitive infrared space telescope so far. However, astronomers consider these galaxies to be the tip of the iceberg and expect to find many more sources when searching with more sensitive instrument, such as the FIRST telescope already planned by ESA as ISO's successor. [Image Date: 24-07-98] [98.07.001-001]