Free Astronomy Magazine March-April 2019

15 MARCH-APRIL 2019 SPACE CHRONICLES mation could be much lower than the observed brightness suggests,” she added. The quasar existed at a transitional period in the universe’s evolution, called reionization, where light from young galaxies and qua- sars reheated the obscuring hydro- gen that cooled off not long after the big bang. The quasar would have gone unde- tected if not for the power of grav- itational lensing, which boosted its brightness by a factor of 50. However, because very distant qua- sars are identified by their red color (due to absorption by diffuse gas in intergalactic space), sometimes their light is “contaminated,” and looks bluer because of the starlight of an intervening galaxy. As a result, they may be overlooked in quasar searches because their T his artist’s impression shows how J043947.08+163415.7, a very distant quasar powered by a supermassive black hole, may look close up. This object is by far the brightest quasar yet discov- ered in the early Universe. [ESA/Hubble, NASA, M. Kornmesser] G raphic animation of the quasar J043947.08 + 163415.7, a very distant object powered by a supermassive black hole. [ESA/Hubble, NASA, M. Kornmesser]