Two telescopes have discovered the closest supermassive black holes to us to date. This pair of black holes is located just 300 light-years from Earth and was observed at different light wavelengths using NASA’s Chandra X-ray Observatory and Hubble Space Telescope.
While black holes become invisible against the dark void of space, these two black holes shine brightly as the gas and dust they consume accelerate and heat up to high temperatures. The two objects, which orbit each other, are known as active galactic nuclei.
Active galactic nuclei are supermassive black holes that release bright streams of material and powerful winds that can shape the very galaxies in which they are found.
This pair of black holes is the closest detected through visible light and X-rays. While other pairs of black holes have been observed before, they are typically much farther away. Astronomers discovered these black holes dancing together at the center of a colliding galaxy pair named MCG-03-34-64, located 800 light-years away.
This pair of black holes is just 300 light-years from Earth.
Astronomers serendipitously found the black holes when observations from Hubble revealed three bright points of light within the glowing gas stream of a galaxy.
“We did not expect to witness something like this,” said lead researcher Anna Trindade Falcão from the Harvard-Smithsonian Center for Astrophysics in a statement. According to this researcher: “The scene is not a common phenomenon in the nearby universe and reveals to us that something is happening inside the galaxy.”
The research team was thrilled when Hubble detected three optical diffraction spots in a concentrated area of the galaxy MCG-03-34-64. These diffraction spots appear when light from a small region of space bends around the mirror inside the telescope.
Hubble’s observations were made in optical light, visible to the naked eye, but astronomers were uncertain about what they were seeing. Falcão’s research team revisited this galactic region using the Chandra Observatory under X-ray light.
When scientists observed the galaxy with Chandra, they could precisely identify two strong X-ray light sources that matched the optical light sources detected by Hubble, Falcão noted. “We pieced these clues together and concluded that we are likely observing two supermassive black holes situated closely together.”
The research team also referenced archived radio wave data collected by the Karl G. Jansky Very Large Array radio telescope in Socorro, New Mexico. This duo of black holes was also found to emit high-energy radio waves.
“When you see strong light in optical, X-ray, and radio wavelengths, many things can be ruled out to conclude that they can only be nearby black holes. When you piece all the fragments together, you get the picture of this (active galactic nucleus) duo,” researcher Falcão explained.
Meanwhile, the third diffraction spot observed by Hubble has an undetermined origin, and the research team needs more data to understand what it could be. This light source may be from gas disturbed by the powerful material release from one of the two black holes.
“We would not be able to see all these complexities without Hubble’s amazing resolution,” researcher Falcão stated.
Astronomers have observed pairs of black holes closer than these two via radio telescopes, but those pairs have not been observed at other light wavelengths.
Both supermassive black holes were once at the centers of their respective galaxies, but a galaxy merger has brought the two objects much closer together. Ultimately, according to NASA, their tight spiral will lead to a merger in about 100 million years, resulting in the release of gravitational waves or ripples in the fabric of space and time.
