Hubble Directly Observes the Disk Around a Black Hole

International scientists have observed a black hole swallowing up a quasar accretion disc. The quasar disc is approximately 100-300 billion kilometers across and is identified by its brightly glowing matter. Although the disc lays billions of light-years away from Earth, the NASA/ESA Hubble Space Telescope was recently used in an innovative way to observe phenomena normally too small to be seen even by the powerful Hubble.

As the Hubble focuses on distant galaxies, scientists utilize gravitational lensing – a process by which the beams of light behind an object are “bent” like a lens by the gravity of the object, essentially magnifying what is behind the object. This precise method allows scientists to determine the size and temperature variations of the disc. Until the utilization of gravitational lensing, the sheer distance of quasars has prevented any direct observation and scientists have consequently relied on theoretical extrapolations.

Scientists noticed subtle color differences which indicate differing temperatures within the quasar disc. As the quasar moves closer to the black hole, the matter reflected becomes bluer and, therefore, is hotter. The scientific team was able to measure the hot diameter as well as other temperature variations further from the hole.

Galaxy stars can be utilized in a manner similar to a scanning microscope so that quasar disc features may be more intimately studied. Stars moving across the quasar’s light amplify it and reflect precise color information in a line crossing the quasar disc. Subtle color differences are caused, in part, by normal galactic space dust. Calculating the manner and range to which the galaxy’s dust impedes the transmission of light is also a significant result of the study.

The lead scientist in the study, Jose Muñoz, stated that since quasars are so distant, they will probably never be directly viewed by a telescope. The recent gravitational lensing innovation means that, although “quasars’ physical properties are not yet well understood, this new ability to obtain observational measurements is … opening a new window to help understand the nature of these objects.” He goes on to stress the relevance of the study results is “… because it implies we are now able to obtain observational data on the structure of these systems, rather than relying on theory alone.”

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