Free Astronomy Magazine September-October 2015

36 SEPTEMBER-OCTOBER 2015 SPACE CHRONICLES All the energy in the Universe was created in the Big Bang, with some portion locked up as mass. Stars shine by converting mass back into energy, as described by Einstein’s famous equation E=mc 2 . The GAMA study sets out to map and model all of the energy generated within a large volume of space today and at different times in the past. “While most of the energy sloshing around in the Universe arose in the after- math of the Big Bang, additional energy is constantly being generat- ed by stars as they fuse elements like hydrogen and helium together,” Simon Driver says. “This new energy is either absorbed by dust as it trav- els through the host galaxy, or es- capes into intergalactic space and travels until it hits something, such as another star, a planet, or, very oc- casionally, a telescope mirror.” The fact that the Universe is slowly fad- ing has been known since the late 1990s, but this work shows that it is happening across all wavelengths from the ultraviolet to the infrared, representing the most comprehen- sive assessment of the energy out- put of the nearby Universe. The Uni- verse will decline from here on in, sliding gently into old age. Charting the slow death of the universe by ESO A n international team of as- tronomers studyingmore than 200,000 galaxies has measured the energy generated within a large portion of space more precisely than ever before. The study involves many of the world’s most powerful tele- scopes, including ESO's VISTA and VST survey telescopes at the Paranal Obser- vatory in Chile. Supporting observa- tions weremade by two orbiting space telescopes operated by NASA (GALEX and WISE) and another belonging to the European Space Agency (Herschel). The research is part of the Galaxy And Mass Assembly (GAMA) project, the largest multi-wavelength survey ever put together. “We used as many space and ground-based telescopes as we could get our hands on tomeasure the energy output of over 200 000 galaxies across as broad a wavelength range as possible,” says Simon Driver (ICRAR, The University of Western Australia), who heads the large GAMA team. The survey data includes measurements of the energy output of each galaxy at 21 wavelengths, from the ultraviolet to the far infrared. This dataset will help scientists to better understand howdif- ferent types of galaxies formandevolve. T he above composite picture shows how a typical galaxy appears at different wavelengths in the GAMA survey. This huge project has measured the energy output of more than 200,000 galaxies and repre- sents the most comprehensive assessment of the energy output of the nearby Universe. The results confirm that the energy produced in a sec- tion of the Universe today is only about half what it was two billion years ago and find that this fading is occurring across all wavelengths from the ultraviolet to the far infrared. [ICRAR/GAMA and ESO] n