A new SDSS press release is up! This time, we’re featuring work led by Nurten Filiz Ak of Penn State, studying disappearing broad absorption line troughs in quasars. They have found several quasars in which the BAL trough disappears over a nine-year period. The simplest explanation for this observation is that as the quasar’s accretion disk has rotated, carrying the absorption region out of the line of sight between us and the quasar. In other words, as the press release says, the gas cloud is…
An artist’s impression of a quasar, along with its spectra from SDSS observations