An international group of astronomers studied the brief but brilliant light of a distant gamma-ray burst, as it passed through its own host galaxy and another galaxy nearby. Using observations from the European Southern Observatory’s (ESO’s) Very Large Telescope at the Paranal Observatory in Chile, the researchers found that these two galaxies, which formed when the universe was relatively young, are richer in heavier chemical elements than the sun. One burst, officially called GRB 090323, was first detected by NASA’s Fermi Gamma-ray Space Telescope. Shortly after, it was also spotted by X-ray instruments on NASA’s Swift satellite and by the gamma-ray burst detector on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile.
The observations showed that the light from the gamma-ray burst passed through two very distant galaxies, so distant that they are seen as they were about 12 billion years ago or 1.8 billion years after the Big Bang. Such galaxies in the early universe are very rarely caught in the glare of a gamma-ray burst. As light from the gamma-ray burst passed through the galaxies, gas in the galaxies acted as a filter and absorbed some of the light at certain wavelengths. The results of the new study also support the idea that gamma-ray bursts may be associated with vigorous and widespread star formation. Such energetic star formation in these types of galaxies may have halted early on in the history of the universe.