Lights Burning and Churning Through Time

The light is going the distance.

Some celestial (light-producing) objects are farther away than others. The three larger galaxies in today’s image are nearby, located in the Fornax galaxy cluster. As you can see, light comes from other galaxies much farther away: the smaller points are galaxies, too. We measure the patterns in the galaxies that are far away from us and compare that to the patterns of the nearby galaxies. Differences in this pattern give us indispensable clues about how dark energy has affected space-time over the last several billions of years.

And some of the bright points (galaxies) are behind the large galaxy near the center (NGC1374), yet we can see them. What does that tell us about the brightness in different parts of galaxies? If you look closely, we can see background galaxies (those behind) everywhere—except a small patch near the center. This is due to the fact that the centers of galaxies are brighter than their outskirts.

Light from distant regions of space can travel up to billions of light-years, to accidentally land here on Earth — to land on a small spot on the side of a mountain in Chile, where the Dark Energy Camera is waiting to capture it. To measure the expansion of the universe, the Dark Energy Survey needs to measure light from hundreds of millions of galaxies, all differing in their colors, brightnesses and locations. These properties will betray their patterns, which we must decipher.

Light travels the distance, and we’re hunting it all the way.

Written by:   Det. B. Nord [FNAL]

Image by:   Det.’s Nikolay Kuropatkin [FNAL], Martin Murphy [FNAL]