A neutron star merger (GW170817/GRB 170817A) puzzles astronomers since it continues to brighten, months after it was first observed!! The merger was initially detected in August by LIGO (Laser Interferometer Gravitational-Wave Observatory) and the detection was later confirmed by the European Virgo detector and other ground and space telescopes. This was the first time that astronomers were able to observe a cosmic event with both light and gravitational waves!
During the merging process of two neutron stars the generated jets bright for a short time as they smash into the surrounding material and then fade away. However, in this case, the afterglow turned out to be brighter in both the X-rays and in the radio, more than three months after the initial detection!
This indicates that the collision is more complex than scientists initially imagined and more complicated models are required to explain the physics that drives this phenomenon. Continued observations using the Chandra X-ray observatory will be critical for validating these models!
Publication: Ruan et al. 2018