Dark energy is controlling the expansion of the universe and dark matter mapping will be key to us understanding it. A new camera named Hyper Suprime-Cam has been installed on the Subaru space telescope in Japan and has revealed nine large areas of dark matter in the constellation of Cancer.
The team behind the Hyper Suprime-Cam is now ready to work out how dark matter has changed in the Universe over time and the history surrounding the expansion of the Universe.
Dr. Satoshi Miyazaki, is lead developer on Hyper Suprime-Cam said, “Now we know we have the both a technique and a tool for understanding dark energy. We are ready to use Hyper Suprime-Cam to create a 1000 square degree dark matter map that will reveal the expansion history of the universe with precise detail.”
Theory of expansion
Edwin Hubble first discovered that the universe was expanding in 1929 but initial views were that this was slowing. Since 1990, we have established that it is expanding at an increasing rate. The expansion rate throws up a number of questions but a key one is if the universe is expanding more rapidly it will take longer for new galaxies to form and if it is expanding more slowly, galaxies will develop more quickly.
Detecting dark matter
The challenge in detecting the dark matter is that it doesn’t emit light so cannot be identified by telescopes. There is a technique that can overcome this challenge, which is called “weak lensing”. This is where the dark matter acts as a lens from more distant light and bends it. By analysing data from how the light is being changed, it is possible to assess the dark matter.
By understanding the history of dark matter and how it relates to the expansion of the universe, it will give us an insight into the physical aspects of dark energy and how it has evolved over time.
In order to gather enough data, the astronomers will need to observe galaxies which are greater than 1 billion light years away across a region larger than 1000 square degrees.
The Hyper Suprime-Cam has an 870 million-pixel image capability and recently observed 2.3 square degrees of sky in a two-hour exposure, which revealed very strong images of many galaxies. By calculating the individual shapes of the galaxies the team were able to map the dark matter behind them. They found 9 areas of dark matter.