A Tour of A New Signal for a Neutron Star Collision Discovered
(Credit: NASA/CXC/A. Hobart)
[Runtime: 02:39]

With closed-captions (at YouTube)

A bright burst of X-rays has been discovered by NASA's Chandra X-ray Observatory in a galaxy 6.6 billion light years from Earth. This event likely signaled the merger of two neutron stars and could give astronomers fresh insight into how neutron stars — dense stellar objects packed mainly with neutrons — are built.

When two neutron stars merge they produce jets of high energy particles and radiation fired in opposite directions. If the jet is pointed along the line of sight to the Earth, a flash, or burst, of gamma rays can be detected. If the jet is not pointed in our direction, a different signal is needed to identify the merger.

The detection of gravitational waves — ripples in spacetime — is one such signal. Now, with the observation of a bright flare of X-rays, astronomers have found another signal, and discovered that two neutron stars likely merged to form a new, heavier and fast-spinning neutron star with an extraordinarily strong magnetic field.

Chandra observed the source, dubbed XT2, as it suddenly appeared and then faded away after about seven hours. The source is located in the Chandra Deep Field-South, the deepest X-ray image ever taken that contains almost 12 weeks of Chandra observing time, taken at various intervals over several years. The source appeared on March 22nd, 2015 and was discovered later in analysis of archival data.

This result is important because it gives astronomers a chance to learn about the interior of neutron stars, objects that are so dense that their properties could never be replicated on Earth.

A Quick Look at A New Signal for a Neutron Star Collision Discovered
(Credit: NASA/CXC/A. Hobart)
[Runtime: 1:08]

A bright blast of X-rays from a source in a distant galaxy has led astronomers to a fascinating discovery.

Neutron stars are dense stellar objects that contain extreme physical conditions that are impossible to replicate on Earth.

Occasionally, they can merge with each other. Until now, every neutron star merger seen has been followed by a flash of gamma rays.

This new source, dubbed XT2, is different. Scientists saw it changing in X-rays in Chandra data from 2015.

By comparing the Chandra observations to theoretical models, researchers identified XT2 as a neutron star merger.

This new finding will help astronomers learn more about the interior of neutron stars and give them a new method for finding mergers between them.

Timelapse
(Credit: NASA/CXC/Uni. of Science and Technology of China/Y. Xue et al)
[Runtime: 00:12]

These images show the location of an event, discovered by Chandra, that likely signals the merger of two neutron stars. Unlike other neutron star mergers, this one was not observed as a gamma-ray burst. This field of view that shows the Chandra image focuses only on the source dubbed XT2. A bright burst of X-rays in XT2 could give astronomers fresh insight into how neutron stars — dense stellar objects packed mainly with neutrons — are built.