A galactic collision might have pushed a supermassive black hole (SMBH) out of its host galaxy and astronomers are hoping that this object might reveal some of the mysteries surrounding the cosmos' heavyweights.
This particular SMBH, known as CXO J101527.2+625911, is 160 million times the mass of the Sun and is located in an elliptical galaxy 3.9 billion light-years away. Based on observations, the SMBH is 4,109 light-years away from the core of the galaxy, which is unusual. The researchers also discovered that it's moving at 175 kilometers (109 miles) per second, strongly hinting that this object is moving outwards.
Based on this, astronomers believe CXO J101527, as it's known for short, is a recoiling supermassive black hole. In a paper accepted for publication in the Astrophysical Journal, astronomers suggest that the black hole was formed by the merger of two smaller black holes and their interaction was so violent that it propelled the supermassive black hole away from the core.
Since we don’t exactly how these supermassive black holes merge, astronomers hope to use CXO J101527 and other similar objects to understand black holes collisions. Although recoiling SMBHs might be the exception rather than the rule.
The discovery wasn’t serendipitous. Searching through X-ray data for thousands of galaxies, the astronomers found evidence of a powerful X-ray source off-center from its galaxy. This was not an automatic confirmation of a recoiling supermassive black hole, so the team used the optical observations from the Sloan Digital Sky Survey and matched them with NASA’s Chandra detection of X-rays sources. From this combined catalog, they were able to find the source.
The source is a moving black hole, but what’s not clear is what it has left behind. Is the core of the galaxy now empty or is there another black hole there? If there is another black hole then this would not be a recoiling SMBH.
Based on infrared and radio observations as well as how CXO J101527 and its galaxy are moving, the scientists think it’s unlikely that there is another black hole hiding in the center. There’s also another nugget of indirect evidence. The galaxy is an elliptical and these objects are the product of mergers between galaxies, a likely location for recoiling SMBHs. The team also discovered disturbances and star-formation on the edge of this specific galaxy, hallmarks of a recent merger.
The clues all seem to fit but it’s still a bit early to claim certainty. The team is currently planning more observations to hopefully confirm their findings.