Researchers collected data from the kilonova in every part of the electromagnetic spectrum. In the early hours the explosion appeared blue and featureless — the light signature of a very young, very hot new celestial body. But unlike supernovas, which can linger in the sky for months, the explosion turned red and faded. —— news.nationalgeographic.com —— nature.com
By separating light from the collision into its component parts, scientists could distinguish the characteristic signals of heavy elements like silver and gold coalescing in the cooling cloud of material. Wedding rings and uranium bombs are elemental echoes of these merging neutron stars.
The observations confirmed theoretical models of what a kilonova might look like. For millennia the two dead stars circled each other at nearly the speed of light, shaking off gravitational waves, which in turn pulled them closer together. When the husks smashed together, dinosaurs still walked the planet. The beams of light and gravitational shock waves from stars' collision finally reached Earth in August.
The fact that the signals arrived so close together — just 1.7 seconds elapsed between the first gravitational wave detection and the arrival of the gamma ray burst — also proves one of Einstein's predictions: gravitational waves move at light speed.
“While I’m not surprised that Einstein is right," McEnery said, "it’s always nice to see him pass another test.”
Scientists don’t yet know what happened in the wake of the kilonova. Neutron stars are too faint to be seen from so far away, so researchers can’t tell if the merger produced one large neutron star, or if the bodies collapsed to form a black hole, which emits no light at all.
But after two months of analysis, the collaborators were ready to inform the world about what they have so far. Their results were announced Monday in more than a dozen papers in the journals Nature, Science and the Astrophysical Journal Letters.
The collaboration’s capstone paper in Astrophysical Journal Letters lists roughly 3,500 authors, approaching the record set in 2015 by 5,154 Large Hadron Collider physicists who estimated the mass of the Higgs boson. If gravitational wave research had already weakened the stereotype of a lone astronomer genius, the dawn of multi-messenger astrophysics dealt it a fatal blow.
“From this point onward, the more we want to know, the more we need to work together.” said Laura Cadonati, an astrophysicist at the Georgia Institute of Technology and LIGO representative.
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