Four Quasar Images Surround a Galaxy Lens
Image Credit: ESA/Hubble, NASA, Sherry Suyu et al.
Explanation: An
odd thing about the group of lights near the center is that four of them are the same distant
quasar. This is because the foreground galaxy -- in the center of the quasar images and the
featured image -- is acting like a choppy
gravitational lens. A perhaps even
odder thing is that by watching these
background quasars flicker, you can estimate the
expansion rate of the universe. That is because the flicker timing increases as the
expansion rate increases. But to
some astronomers, the
oddest thing of all is that
these multiply imaged quasars indicate a universe that is expanding a bit faster than has been estimated by different methods that apply to the early
universe. And that is because ... well, no one is sure why. Reasons might include an unexpected distribution of
dark matter, some unexpected effect of
gravity, or something completely different. Perhaps future observations and analyses of this and
similarly lensed quasar images will remove these oddities.
No comments:
Post a Comment