Evrim Yazgin
Cosmos science journalist
Astronomers have found radio signals from hot gas surrounding a supermassive black hole. The discovery could help reveal hidden black holes across the universe.
The black hole in question is 12.9 billion light-years away. Its light has reached Earth from a time when the universe was just 800 million years old. The new research, published in Nature Astronomy, is the most detailed look scientists have had at the molecular gas near a black hole from such an early time in the universe’s history.
“The findings help us understand how black holes grow from tiny seeds in the early universe to supermassive black holes, and the challenges posed by dust and gas that can obscure them,” says co-author Takafumi Tsuki, a researcher from the Australian National University.
The dense molecular gas known as J231038.88+185519.7 (or J2310 for short) has been known to astronomers for a while as a quasi-stellar object, otherwise known as a quasar. These are powered by a supermassive black hole at their centre making them among the brightest objects in the universe.
Peering into quasars is hard despite their brightness.
The new study uses ultra-high-resolution observations made by the Atacama Large Millimeter Array (ALMA) in Chile. This allowed the team to see the heating mechanisms affecting the gas within just a few hundred light-years of the black hole.
They estimate that the supermassive black hole is between 2 to 4 billion times the mass of our Sun.
“We discovered that intense X-ray radiation emitted by the material spiralling around the black hole, along with strong winds and shock waves, heat the gas to energy states far higher than what’s typically seen in normal galactic environments, where the main source of energy comes from the ultraviolet radiation from stars,” explains Tsukui.
Tsukui adds that many black holes may be concealed by dust, waiting to be discovered.
“As the radio waves observed by ALMA are not easily absorbed by dust, our technique becomes a powerful tool for discovering ‘hidden’ supermassive black holes.”
“The breakthrough in our research comes from specifically targeting radio emissions from carbon monoxide molecules in higher energy states, which uniquely reveals the hot gas conditions in the immediate vicinity of the supermassive black hole,” Tsukui says.
The team say their focus on signatures relating to carbon monoxide could also help build a fuller picture of supermassive black holes in the early universe.
