Astronomers Unveil Most Accurate Map Of Dark Matter In The Universe
The Dark Energy Survey, a collaboration of over 400 scientists from seven countries, unveiled the largest map of dark matter and energy in the universe resulting from the first year of the project's five-year observation.
DES scientists expressed that the new map is not only more accurate with its less than 5 percent error bar, but it is also consistent with the early measurements and models derived from the European Space Agency's Planck satellite.
To gather the data that led to the amazing map, DES scientists mounted a 570-megapixel camera called DECam on the 4-meter Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.
DES scientists developed and carried out precision tests with the help of the weak gravitational lensing phenomenon, and analysis of the data led to the creation of a map containing the distribution of mass of dark matter. It is also able to determine how dark matter evolves over time.
That's Amazing, But What Does It Mean?
We know that the universe has been expanding since the Big Bang, but there are still many questions about its expansion that remain a mystery and which scientists are trying to find answers to.
The results from the DES model now allow scientists to make more precise predictions about the expansion of the universe because of two very important reasons: first is that DES was able to gather data consistent with the ESA's cosmic microwave background (CMB) model, which is based on the early structure of the universe. The second reason is that it supports the simplest theories on dark matter and dark energy, which shows that the DES is most probably on the right track.
"While Planck looked at the structure of the very early universe, DES has measured structures that evolved much later. The growth of these structures from the early ages of the universe until today agrees with what our models predict, showing that we can describe cosmic evolution very well," Daniel Gruen explained. Gruen is a NASA Einstein postdoctoral fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC).
For a better visual, consider the CMB model as a photo of a toddler and the DES model as a picture of the same child at 8 years old. Since the DES model is consistent with the CMB model, scientists will be able to determine not only the rate and precise measurement of the toddler as they reach 8 years of age, but they will also be able to predict how much the child will have grown at 13 years old and beyond.
"For the first time, we're able to see the current structure of the universe with the same clarity that we can see its infancy, and we can follow the threads from one to the other, confirming many predictions along the way," Scott Dodelson of Fermilab said. Dodelson is one of the lead scientists of the project.
The SLAC National Accelerator Laboratory released a video showing 3D imagery of the 2D map the DES collaboration provided. Watch it below.
How The DES Scientists Created The Map
In their search to find the answers, astrophysicists turned to dark matter and dark energy, which are invisible and mysterious matter and force that drive the expansion of the universe.
Both are invisible and virtually undetectable, but scientists believe that the universe is filled with them, so they had to use other means to try and pinpoint its existence throughout the universe. That is where weak gravitational lensing comes in.
Using this phenomenon, scientists with the DES precisely measured the shape of 26 million galaxies and mapped out their precise locations in the universe. Since the theory is that the 26 percent of the universe is made up of dark matter and space is filled with about 70 percent dark energy, the involved astrophysicists were able to create a 1-billion-light-year map of the invisible matter's distribution.
The photo below is one of the stunning results of their efforts.
The 1-billion-light-year dark matter map released by the DES collaboration is only the result of the first year of the study. The final map is expected to be more than three times larger than the current map. DES is currently in its fourth year and will begin its fifth and final year of observation this August.