University of Maryland Astronomers Find X-rays Lingering Years After Landmark Neutron Star Collision

A new start-to-finish view of a neutron star merger—the most complete such process ever observed—rewrites the way scientists understand these events. A UMD-led study of the event was published today in the journal Monthly Notices of the Royal Astronomical Society.

In the three years since the landmark detection of a neutron star merger from gravitational waves, an international team of researchers led by University of Maryland astronomer Eleonora Troja has been continuously monitoring the subsequent radiation emissions. Its analysis provides possible explanations for X-rays that continued to radiate from the collision long after models predicted they would stop. The study also reveals that current models of neutron stars and compact body collisions are missing important information.

“We are entering a new phase in our understanding of neutron stars,” said Troja, an associate research scientist in the Department of Astronomy and lead author of the paper. “We really don’t know what to expect from this point forward, because all our models were predicting no X-rays, and we were surprised to see them 1,000 days after the collision event was detected. It may take years to find out the answer to what is going on, but our research opens the door to many possibilities."

The neutron star merger that Troja’s team studied—GW170817—was first identified from gravitational waves detected by the Laser Interferometer Gravitational-wave Observatory and its counterpart Virgo on Aug. 17, 2017. Within hours, telescopes around the world began observing electromagnetic radiation, including gamma rays and light emitted from the explosion. It was the first and only time astronomers were able to observe the radiation associated with gravity waves, although they long knew such radiation occurs. All other gravity waves observed to date have originated from events too weak and too far away for the radiation to be detected from Earth.

Read the full release on the College of Computer, Mathematical, and Natural Sciences website.