The US National Aeronautics and Space Administration (NASA) astronomers have discovered, through new technology, that a supermassive black hole at the center of a galaxy is rotating vertically relative to the plane of the galaxy, appearing as if the black hole is “lying on its side,” leaving them puzzled.
NASA pointed out that the galaxy, named NGC 5084, is located about 80 million light-years away from Earth and has been known to the astronomical community for many years. However, the “sideways” black hole at the center of this galaxy has been hidden in old data and unknown to the public.
By using a new image analysis technology developed by NASA’s Ames Research Center, astronomers reexamined the historical observational data from the Chandra X-ray Observatory and uncovered this secret.
Unexpectedly, astronomers using this new technology discovered that NGC 5084 emits four (two pairs of) long plasma jets. Surprisingly, the second pair is aligned on the galaxy’s plane, forming an “X” shape with the other pair. Plasma jets, which are streams of hot ionized gas, are not commonly found in galaxies and usually exist in only one or two streams.
The presence of the second pair of plasma jets strongly suggests that there may be a supermassive black hole hidden at the center of the galaxy, but there could also be other explanations. After reviewing observations from NASA’s Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array, astronomers discovered a small dusty disk rotating at the center of the galaxy.
This indicates the existence of a black hole at the center of the galaxy, with its rotation direction almost perpendicular to the overall rotation of the galaxy. In a sense, this dusty disk and black hole resemble being “lying on its side.”
Alejandro Serrano Borlaff, a research scientist at Ames Research Center and the lead author of this study, stated that combining all observation results shows that NGC 5084 has undergone significant changes recently.
Pamela Marcum, an astrophysicist at the center, mentioned, “Detecting two pairs of X-ray jets in a galaxy is quite rare. This unusual cross-shaped structure, along with the ‘sideways’ dusty disk, offers us unique clues to understand the evolutionary process of the galaxy.”
Astronomers typically expect the X-ray energy emitted by large galaxies to be roughly spherical and evenly distributed. When observation results show otherwise, such as being concentrated in a pair of X-ray jets, they understand that a significant event has disturbed the galaxy at some point in time.
NGC 5084 may have experienced significant events in its history, causing the central black hole to “flip” and produce double pairs of jets. These significant events include collisions with another galaxy and overheat gas being ejected from the top and bottom of the galaxy’s plane, forming chimney-like structures.
The study results were published on December 18 in The Astrophysical Journal.