Science year in review: Neutron star smashup is the gift that keeps on giving
For the second year in a row, the journal Science is hailing a discovery sparked by the Laser Interferometer Gravitational-Wave Observatory as the Breakthrough of the Year.
Last year, the breakthrough was LIGO’s first-ever detection of a gravitational-wave burst thrown off by the merger of two black holes. This time, the prize goes to the studies spawned by the first observed collision of two neutron stars.
More than 70 observatories analyzed the data from the Aug. 17 event, which came in the form of gravitational waves as well as electromagnetic emissions going all the way from radio waves to gamma rays.
“The amount of information we have been able to extract with one event blows my mind,” Georgia Tech physicist Laura Cadonati, deputy spokesperson for the LIGO team, told Science.
The event demonstrated that neutron star mergers produce short gamma-ray bursts, which helped resolve a longstanding astronomical mystery about the bursts’ origins. It also provided the best example of a kilonova, a phenomenon that’s thought to give rise to gold and other elements heavier than iron.
LIGO’s Nobel-winning discoveries have proved the worth of the roughly $600 million project, which makes use of twin detectors in Hanford, Wash., and Livingston, La., to detect subtle ripples in the fabric of spacetime. But the thousands of scientists who make use of LIGO’s data aren’t done yet.
Just this week, a study published in Nature laid out the likeliest explanation for what happened in the aftermath of the neutron-star collision. Based on the timing and strength of emissions in various wavelengths, astronomers said the best model suggests that superfast jets of material from the kilonova produced a “cocoon” of debris around the blast site.
The cocoon would absorb energy from the jets, resulting in a wide-angle outflow of material as well as a steady rise in radio and X-ray emissions. Observations made by radio telescopes and the Chandra X-ray Observatory matched the model.
“It was very exciting to see our prediction confirmed,” Caltech astronomer Gregg Hallinan, one of the study’s co-authors, said in a news release. “An important implication of the cocoon model is that we should be able to see many more of these collisions by detecting their electromagnetic, not just their gravitational, waves.”
LIGO is currently shut down for upgrades, but it’s a safe bet that there’ll be more breakthroughs when the observatory comes back online next year.
Here are other highlights from Science’s Breakthrough of the Year roundup:
Runners-up for breakthrough honors included the success of cryo-electron microscopy, the development of a portable neutrino detector, the identification of a 300,000-year-old Homo sapiens skull from Morocco, a new genetic-engineering method called base editing, the popularity of biology preprints, the FDA’s thumbs-up for a biomarker-based cancer drug called Keytruda, the designation of a new orangutan species, a climate study that looked at 2.7 million-year-old ice from Antarctica, and a gene-therapy technique that can stop a fatal neuromuscular disease.
Science listed three “breakdowns of the year”: the dysfunctional relationship between the U.S. research community and the Trump administration; the abandonment of an effort to save a small porpoise called the vaquita, which lives only in the Gulf of California; and the year’s high-profile cases of sexual harassment and discrimination in the scientific community.
