For the first time, Northwestern University-led astronomers may have detected an afterglow from a kilonova.
For the first time, Northwestern University-led astronomers may have detected an afterglow from a kilonova.
A kilonova occurs when two neutron stars — some of the densest objects in the universe — merge to create a blast 1,000 times brighter than a classical nova. In this case, a narrow, off-axis jet of high-energy particles accompanied the merger event, dubbed GW170817. Three-and-a-half years after the merger, the jet faded away, revealing a new source of mysterious X-rays.
As the leading explanation for the new X-ray source, astrophysicists believe expanding debris from the merger generated a shock — similar to the sonic boom from a supersonic plane. This shock then heated surrounding materials, which generated X-ray emissions, known as a kilonova afterglow. An alternative explanation is materials falling toward a black hole — formed as a result of the neutron star merger — caused the X-rays.
Either scenario would be a first for the field. The study was published today (Feb. 28), in The Astrophysical Journal Letters.
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Image: An artist’s conception illustrates the aftermath of a “kilonova,” a powerful event that happens when two neutron stars merge. (Credit: NASA/CXC/M. Weiss)
