Chandra Release - May 31, 2018

Visual Description: GW170817

This graphic contains three panels with an artist's illustration up top and two panels of X-ray images at bottom. The subject of all of these is the gravitational wave source named GW170817. The illustration features two bright, glowing white and blue spheres in the center that look to be merging, surrounded by smaller, darker purple circles all around on a grid. After two separate stars underwent supernova explosions, two ultra-dense cores (that is, neutron stars) were left behind. These two neutron stars were so close that gravitational wave radiation pulled them together until they merged and collapsed into a black hole. The artist's illustration shows a key part of the process that created this new black hole, as the two neutron stars spin around each other while merging. The purple material depicts debris from the merger. NASA's Chandra X-ray Observatory observed GW170817 multiple times. An observation a few days after the event failed to detect a source, but subsequent observations 9, 15 and 16 days after the event, resulted in detections (bottom left, a dim purple source). The source went behind the Sun soon after, but further brightening was seen in Chandra observations about 110 days after the event (bottom right, a very bright purple-white source), followed by comparable X-ray intensity after about 160 days. The pattern in the Chandra data were critical in determining if the neutron star merger created a heavier neutron star or a black hole.