An artist's impression of a quasar like one of the nineteen found by this study. The black dot in the center represents the supermassive black hole at the center of the quasar. The red-and-yellow spiral surrounding it shows the accretion disk of hot gas falling into the black hole. Some of this gas is ejected as the quasar's wind, which is shown in light blue. The size of the accretion disk shown is comparable to the size of our solar system. The inset at the top right shows two SDSS spectra for the same quasar (named SDSS J093620.52+004649.2). The upper spectrum (blue) was taken in 2002, while the lower spectrum (red) was taken in 2011. The deep, wide valley in the 2002 spectrum is a so-called "broad absorption line" — a feature which has disappeared from its spectrum by 2011. // Credit: NASA/CXC/M. Weiss, Nahks Tr'Ehnl, Nurten Filiz Ak