The nature of dark energy is one of the outstanding problems in cosmology today. Something is causing the universe’s expansion to accelerate, but what? Numerous techniques are being developed to attack this problem, and astronomers have demonstrated such a technique with the largest fully-steerable radio telescope.
SLIDE SHOW: Visualizing the inner workings of a Type Ia supernova — the “standard candle” astronomers use to measure the effects of dark energy.
Theories predict that acoustic, or sound waves, from the very early universe should have left their mark in a detectable way. (What if you could hear these sounds?) By measuring the large-scale structures left behind by the sound waves, astronomers may be able to make precise measurements of some of the parameters of dark energy, thus getting one step closer to determining its nature.
Astronomers Tzu-Ching Chang, Jeffrey Peterson, Ue-Li Pen, and Kevin Bandura used the Green Bank Telescope in West Virginia to map large, faint structures of hydrogen gas. Hydrogen is the most common element in the galaxy, and hydrogen atoms give off a characteristic “color” of radio light. As they map the hydrogen in the universe on the largest scales, astronomers can search for the structures created by the universe’s characteristic sound waves.
However, mapping the most abundant element in the universe in this way isn’t the easiest task. The team developed new techniques of mapping the faint hydrogen, as well as methods for removing stray radio interferences from man-made sources and from astronomical sources in the foreground. The work paid off as they detected hydrogen ten times further than had been done before.
To unlock the universe’s deepest secrets, astronomers find themselves working harder to find more clever techniques in order to detect fainter and more elusive signals. But isn’t it the challenge that makes it more fun?
Caption: Computer simulation of large scale structure. Credit: Science Magazine