A team of astrophysics researchers from Harvard's Smithsonian Center of Astrophysics reported that an ancient entity with astronomical mass might have punched through the Milky Way, and the evidence lies inside a cosmic structure known as the GD-1 stellar stream.
A stellar stream is a group of galaxy-orbiting stars, which used to be a globular cluster or dwarf galaxy that got rammed into by another galaxy or galaxies.
According to their presentation on the website of the American Physical Society, when examining the star formation within GD-1 a Milky Way-orbiting stream discovered in 2006, the Harvard researchers noticed some surprising discrepancy between their computer simulation and real-life data. There is a big gap inside GD-1, populated with much fewer stars. A perturbation of this scale can only be caused by a body that has a mass 5 million times of our sun, and spreads 33 light-years across, something almost as massive as the Sagittarius A* black hole at the center of our galaxy.
Although they cannot eliminate the possibility that the gap was created by an ancient supermassive black hole which shot through the Milky Way and collided with the GD-1, they also suspected that a high-density cluster of dark matter could have achieved such feat. The team is expecting to conduct more observation and analyses, hoping to reveal the true identity of the massive entity.
Source: Anton Petrov-WhatDaMath (via Youtube)