Fermilab Scientists' Discovery 'Rocks The Science World'

Fermilab Scientists’ Discovery ‘Rocks The Science World’

About 130 million years ago, two extremely dense collapsed stars collided, creating ripples across space and time before exploding in a violent burst of light. In August, scientists on the LIGO and Virgo experiments detected the ripples, called gravitational waves, and then let dozens of astronomers know where to look for the source of those waves.

The image on the left shows the kilonova (just above and to the left of the brightest galaxy) recorded by the Dark Energy Camera. The image on the right was taken several days later and shows that the kilonova has faded. Image: Dark Energy Survey

Fermilab scientists, working as part of a team using the Dark Energy Camera in Chile (the primary tool of the Fermilab-led Dark Energy Survey), were among the first to see the light from the explosion, marking the first time that gravitational waves and their visible counterpart were seen at once.

This discovery rocked the science world, and it opens up many more exciting avenues to understand more about our universe. Read the Dark Energy Survey press release, and check out an animation of the event and a video interview with scientists.

What the scientists had observed via images taken with DECam was the flaring-up and fading over time of a kilonova — an explosion similar to a supernova, but on a smaller scale — that occurs when collapsed stars (called neutron stars) crash into each other, creating heavy radioactive elements.

This particular violent merger, which occurred 130 million years ago in a galaxy near our own (NGC 4993), is the source of the gravitational waves detected by the Laser Interferometer Gravitational-Wave Observatory and the Virgo collaborations on Aug. 17. This is the fifth source of gravitational waves to be detected — the first one was discovered in September 2015, for which three founding members of the LIGO collaboration were awarded the Nobel Prize in physics two weeks ago.

Composite picture of stars over the Cerro Tololo Inter-American Observatory in Chile. Photo: Reidar Hahn/Fermilab

This latest event is the first detection of gravitational waves caused by two neutron stars colliding and thus the first one to have a visible source. The previous gravitational wave detections were traced to binary black holes, which cannot be seen through telescopes. This neutron star collision occurred relatively close to home, so within a few hours of receiving the notice from LIGO/Virgo, scientists were able to point telescopes in the direction of the event and get a clear picture of the light.

“This is beyond my wildest dreams,” said Marcelle Soares-Santos, formerly of the U.S. Department of Energy’s Fermi National Accelerator Laboratory and currently of Brandeis University, who led the effort from the Dark Energy Survey side. “With DECam we get a good signal, and we can show how it is evolving over time. The team following these signals is a well-oiled machine, and though we did not expect this to happen so soon, we were ready for it.”

SOURCE: Fermilab Frontiers newsletter