Two astrophysicists from the Center for Astrophysics | Harvard & Smithsonian (CfA) have proposed a method for seeing the second-closest supermassive black hole to Earth. The black hole is approximately 3 million times the mass of the Sun hosted by the dwarf galaxy Leo I, which is less than 1 million light-years away from Earth.
An independent team of astronomers first proposed its existence in 2021 after noticing stars picking up speed as they approach the center of the galaxy, a sign of a black hole. But direct imaging emission from the black hole was not possible, so CfA astrophysicists suggest a new way to verify its presence.
Second-Closest Supermassive Black Hole May Be Lurking in a Nearby Dwarf Galaxy About 1 Million Light-Years Away
New Way of Detecting the Supermassive Black Hole in Leo I
Study lead author Fabio Pacucci said that black holes are very elusive objects that are sometimes invisible. He added that rays of light cannot escape a black hole, but the environment around them can be extremely bright. However, black holes will not emit light and become impossible to detect from Earth if they do not accrete mass.
According to SciTech Daily, this is the challenge with Leo I. The dwarf galaxy is so devoid of gas available to accrete that scientists often described it as a "fossil."
In their study, titled "Accretion from Winds of Red Giant Branch Stars May Reveal the Supermassive Black Hole in Leo I" published in The Astrophysical Journal Letters, the team suggested that a small amount of mass lost from stars wandering around a black hole could give the accretion rate required to observe it.
Pacucci explains that old stars become very big and red because they would have strong winds that carry a fraction of their mass to the environment. Scientists think that the space surrounding Leo I contain enough of these ancient stars to make them detectable.
Study co-author Avi Loeb noted that observing Leo I could be groundbreaking and that means finding the second-closest supermassive black hole to Earth after the black hole at the center of the Milky Way galaxy.
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Observing Leo I Could Solve Long-Standing Mystery in Astronomy
Detecting the supermassive black hole in Leo I would resolve another astronomical mystery, Space.com reported. For many years, astronomers wonder whether dwarf galaxies possess supermassive black holes. Loeb said that it would challenge long-held beliefs about how galaxies and their central supermassive black holes co-exist.
The center object in the Milky Way and the supermassive black holes at the heart of most giant galaxies holds around a tenth of the total mass of the sphere of stars that surrounds it. The presence of Leo I* in a dwarf galaxy would deviate significantly from this ratio.
Leo I appears to contain a black hole about 3 million times the mass of the Sun, which is similar to the black hole hosted by the Milky Way. Loeb noted that it will be exciting as science advances when something unexpected happens.
But astronomers are still a long way from imaging Leo I. They will be using the space-based Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope in New Mexico to uncover the mysteries of the black hole.
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