Astronomers detect most distant dormant black hole ever found

(CN) — It does not shine. It does not pulse. But deep inside a galaxy over 10 billion light years from Earth, a black hole roughly 6 billion times the mass of our sun has been sitting quietly for billions of years, and astronomers have finally found it.

An international team of researchers, led by Andrew Newman of Carnegie Science in Pasadena, California, made the first direct mass measurement of a dormant black hole from the early universe in the study published Thursday in the journal Science.

The black hole sits at the center of a galaxy known as MRG-M0138. Its light has traveled so far that astronomers are seeing the galaxy as it existed when the universe was only about 3 billion years old, almost a quarter of its current age of 13.8 billion years.

The previous record for the most distant dormant black hole detected using this method was a galaxy about 700 million light years away. This one is 15 times farther.

Finding a dormant black hole is no easy task. When a black hole is actively feeding, gas falling into it releases enormous amounts of energy, creating a quasar, one of the brightest objects in the known universe. A dormant black hole, with nothing falling into it, is effectively invisible.

To find and weigh this one, the team tracked the movement of stars orbiting near the galaxy’s center. Stars close to a massive black hole move faster than those farther away, and by measuring those differences the researchers were able to calculate its mass. It is the same technique used to detect the black hole at the center of our own Milky Way galaxy, but it has never before been applied to a galaxy this far away.

“We were able to detect this black hole at a distance of 10 billion light years by combining [James Webb Space Telescope]’s sharp vision with a natural magnifying glass,” Newman said in a statement.

That magnifying glass is a phenomenon called gravitational lensing. A large cluster of galaxies sits between MRG-M0138 and Earth, and its gravity bends and magnifies the light coming from behind it, effectively acting as a natural telescope.

The effect made the distant galaxy appear about 30 times larger than it otherwise would, giving researchers enough detail to track star movements near the black hole’s core.

“By combining JWST data with gravitational lensing, we could peer inside the black hole’s sphere of influence, where its gravity boosts the speeds of stars,” Newman said in a released statement. “This is one of the best techniques we have to weigh a black hole, so we were excited to extend it to a much earlier period in cosmic history.”

The black hole is not the only thing that has gone quiet. The galaxy surrounding it has also stopped forming new stars, and scientists think the two are connected. When the black hole was young and rapidly growing, the energy it released likely burned off or expelled the free-floating gas that galaxies need to produce new stars, cutting off the whole system in the process.

Senior author Professor Richard Ellis of UCL Physics and Astronomy said the findings open a new window into how the universe formed.

“Determining how stars collectively move within the core of this distant galaxy has allowed us to measure the mass of its otherwise undetectable supermassive black hole,” Ellis said in a statement. “By demonstrating the feasibility of such a technique for galaxies in the early universe, we can now undertake a more complete census of how black holes develop over time and infer their role in shaping galaxy evolution.”

The team is now analyzing James Webb data from other similar galaxies. Future tools — including the Euclid satellite, NASA’s Nancy Grace Roman Space Telescope and the Giant Magellan Telescope currently under construction in Chile — could reveal more examples of gravitational lensing and allow researchers to study star motion in distant galaxies in far greater detail.

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