A new era opens in astrophysics. The precision that allows us to enjoy the Earth’s powerful space observatories is changing the way humans observe the universe, allowing us to witness phenomena millions of light years away; or, what is the same thing, that happened millions of years ago.
A team of scientists at the Carnegie Institute has provided the first image of two neutron stars colliding in the galaxy NGC 4993, about 130 million light years away from Earth, in the constellation of Hydra.
A phenomenon that has important implications. It has caused two historical events: the fifth detection of gravitational waves, for the first time, produced by the fusion of two neutron stars and, in addition, the origin of heavy elements as a result of such fusion, such as gold, platinum and uranium.
In collaboration with scientists at the University of California at Santa Cruz, the team used the Swope telescope at the Las Campanas Observatory to discover the light produced by the fusion, pointing to the origin of a gravitational wave signal.
Not only is it a milestone for physics to observe the clash of two neutron stars, but so are these two historical detections; on the one hand, the gravitational waves (that is, undulations in the space-time tissue, which prove the existence of the same, as predicted by Einstein); and, on the other, the answer to the question that astrophysicists had been asking for decades: when were the heavy elements created?
What are neutron stars?
Neutron stars are incredibly dense remains that lie behind supernova explosions. Theoretical astrophysicists have speculated for years about what happens when two of them merge, but so far this phenomenon has never been observed.
Mergers of black holes do not emit light and therefore are invisible to telescopes. However, for a long time they calculated that the neutron star fusions produce light and gravitational waves, so the detection of these events was impatiently awaited. And finally, this detection has occurred.
To give us an idea of its density: “Only one teaspoon of neutron star weighs as much as all the people on Earth,” according to Carnegie team leader Tony Piro.
“The ability to study the same event with gravitational waves and light is a real revolution in astronomy,” according to Piro. “Now we can study the universe with two completely different probes, which teach us things we could never know with just one or the other.”
How are heavy elements detected?
Scientists separate light from a celestial object into its wavelengths, just as a prism extends sunlight into the colors of the rainbow. Analyzing light in this way helps astronomers measure the speed and chemical composition of cosmic sources.
As scientists follow the blaze of the explosion, they uncovered some key features of the radioactive decay of heavy elements. This suggests that these elements were synthesized after fusion, solving a mystery that had been hidden for 70 years.
In February 2016, the LIGO project announced the first detection of gravitational waves caused by the merger of two black holes, a discovery that received the Nobel Prize in Physics in 2017.