Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                                2021 April 16

                The Doubly Warped World of Binary Black Holes
     Scientific Visualization Credit: NASA, Goddard Space Flight Center,
         Jeremy Schnittman and Brian P. Powell - Text: Francis Reddy

   Explanation: Light rays from accretion disks around a pair of orbiting
   supermassive black holes make their way through the warped space-time
   produced by extreme gravity in this stunning computer visualization.
   The simulated accretion disks have been given different false color
   schemes, red for the disk surrounding a 200-million-solar-mass black
   hole, and blue for the disk surrounding a 100-million-solar-mass black
   hole. That makes it easier to track the light sources, but the choice
   also reflects reality. Hotter gas gives off light closer to the blue
   end of the spectrum and material orbiting smaller black holes
   experiences stronger gravitational effects that produce higher
   temperatures. For these masses, both accretion disks would actually
   emit most of their light in the ultraviolet though. In the video,
   distorted secondary images of the blue black hole, which show the red
   black hole's view of its partner, can be found within the tangled skein
   of the red disk warped by the gravity of the blue black hole in the
   foreground. Because we're seeing red's view of blue while also seeing
   blue directly, the images allow us to see both sides of blue at the
   same time. Red and blue light originating from both black holes can be
   seen in the innermost ring of light, called the photon ring, near their
   event horizons. Astronomers expect that in the not-too-distant future
   they'll be able to detect gravitational waves, ripples in space-time,
   produced when two supermassive black holes in a system much like the
   one simulated here spiral together and merge.

                 Tomorrow's picture: pixels over the weekend
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.

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