Grier Reverberation mapping

Grier Reverberation mapping

An artist's rendering of the inner regions of an active galaxy/quasar

An artist's rendering of the inner regions of an active galaxy/quasar, with a supermassive black hole at the center surrounded by a disk of hot material falling in. The inset at the bottom right shows how the brightness of light coming from the two different regions changes with time. The time span covered by these two light curves is about six months. The bottom plot "echoes" the top, with a slight time delay of about 10 days indicated by the vertical line. This means that the distance between these two regions is about 10 light-days (about 150 billion miles, or 240 million kilometers).

Image: Nahks TrEhnl (www.nahks.com) and Catherine Grier (Penn State) and the SDSS collaboration
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