Free Astronomy Magazine January-February 2016

SPACE CHRONICLES that the brightest and easiest gal- axies to observe — the most mas- sive galaxies in the Universe — are rarer the further astronomers peer into the Universe’s past, whilst the more numerous less bright galaxies are even more difficult to find. A team of astronomers, led by Ka- rina Caputi of the Kapteyn Astro- nomical Institute at the University of Groningen, has now unearthed many distant galaxies that had es- caped earlier scrutiny. They used images from the UltraVISTA survey, one of six projects using VISTA to survey the sky at near-infrared wavelengths, and made a census of faint galaxies when the age of the Universe was between just 0.75 and 2.1 billion years old. UltraVISTA has been imaging the same patch of sky, nearly four times the size of a full Moon, since De- cember 2009. This is the largest The birth of monsters by ESO J ust counting the number of gal- axies in a patch of sky provides a way to test astronomers’ theo- ries of galaxy formation and evolu- tion. However, such a simple task becomes increasingly hard as as- tronomers attempt to count the more distant and fainter galaxies. It is further complicated by the fact E SO’s VISTA survey telescope has spied a horde of previously hidden massive galaxies that existed when the Uni- verse was in its infancy. By discovering and studying more of these galaxies than ever before, astronomers have for the first time found out exactly when such monster galaxies first appeared. The newly discovered massive galaxies are marked on this image of the UltraVISTA field. [ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU]