In a new photo of the Andromeda galaxy, our Milky Way’s neighbor, it unveils an X-ray source which was originally thought to be trapped inside the galaxy. However, it turned out to be 1,000 times farther away. The original study was published in a paper in the Astrophysical journal.
Astronomers used data from NASA’s Chandra X-ray Observatory and ground-based optical telescopes to find a supermassive black hole, that could be the most tightly paired to be seen yet. The black hole is called J0045 + 41 for which astronomers thought it was a star in the Andromeda galaxy. It is expected that the Andromeda galaxy will merge with the Milky Way in roughly 4 billion years.
“We were looking for a special type of star in M31 and thought we had found one,” said lead researcher Trevor Dorn-Wallenstein, a graduate student at the University of Washington in Seattle, in a statement. “We were surprised and excited to find something far stranger!”
When astronomers thought that J0045+41 was inside the Andromeda galaxy, they classified it as a pair of stars which were orbiting each other once every 76 days. However, the data from Chandra revealed that the intensity of the X-ray signal was far beyond that classification. Then Dorn-Wallenstein thought that the pair was instead a binary black hole and neutron star, which led to more study in order to find out.
However, the Gemini-North telescope’s spectral data revealed that J0045+41 needed to include at least one supermassive black hole. That helped researchers calculate the object’s distance. The X-ray source is 2.6 billion light-years away and is likely a pair of supermassive black holes, which are wrapped in a binary orbit. When combined, those black holes have a total mass of 200 million times that of the Sun. The black hole, which is located in the center of the Milky Way is called Sagittarius A* and its mass is around 4 million times the mass of the Sun.
The two black holes shown in a new photo of the Andromeda galaxy are orbiting each other at a close distance, in terms of space, at less than one-hundredth of a light-year. Their distance is only a few hundred times the distance between the Earth and the Sun. The team behind this research thinks that the black holes could have been at the center of a galaxy. As they are slowly being attracted by each other’s gravity, they are expected to collide at some point.