A team of astronomers led by Violeta Gámez Rosas of Leiden University in the Netherlands directed the Very Large Telescope (VLT) in the direction of the Messier 77 galaxy . Messier 77 is a barred spiral galaxy located about 47 million light-years from Earth in the constellation Cetus.
Confirming predictions from about 30 years ago
The experts took detailed images of the dust cloud using the Interferometer of the telescope located at the European Southern Observatory in Chile, discovering a thick ring of cosmic dust that concealed a supermassive black hole, thus confirming a theory related to Active Galactic Nuclei ( AGN), the central region of galaxies that has a higher than expected luminosity.
There are two groups: Type 1 and Type 2 , and scientists have always assumed that the difference between the two was only the angle from which we looked at them and little else. This finding has provided crucial evidence supporting this theory.
Active galactic nuclei are powered by supermassive black holes that feed on material that falls into them and are found at the center of some galaxies. These black holes feed on large volumes of cosmic gas and dust. In type 1, it is possible to see the feeding process directly; the bright core is visible towards the center (that is, the material spirals towards the black hole releasing enormous amounts of energy in the process, even outshining the stars of the galaxy), as seen by telescopes on Earth; in type 2, there is a thick ring of gas and dust almost edge-on that prevents it from being seen, it hides the nucleus.
Finding those of type 2, that is, finding the black hole, which does not emit its own light , is a complicated process that involves solving a fairly complex puzzle.
So astronomers used the images and analyzes of changes in the temperature of cosmic dust to build a map of the dust and pinpoint where the black hole should be. So it was. Astronomers have been able to verify that the active galactic nucleus of Messier 77 (or NGC 1068), is of the archetypal type 2. Detailed heat maps of the core showed that the supermassive black hole is there, hidden behind a thick layer of cosmic dust.
“The actual nature of the dust clouds and their role in both feeding the black hole and determining what it looks like when viewed from Earth have been central questions in AGN studies for the past three decades,” he explains. Violeta Gamez Rosas, leader of the work collected by the journal Nature. “While no single result will answer all the questions we have, we have taken an important step in understanding how AGNs work.”
The Unified Model states that, despite their differences, all AGNs have the same basic structure: a supermassive black hole surrounded by a thick ring of dust. Previously, some evidence had been found to support the unified model, including the detection of hot dust at the center of Messier 77. However, questions remained as to whether this dust could completely hide a black hole, and thus explain why . it glowed less in visible light than others. Until now. Although things remain to be resolved, an important step has been taken in the right direction.
Active Galactic Nuclei
They are some of the brightest and most mysterious objects in the universe, located in the heart of galaxies, and these findings could help pin down the history of the supermassive black hole at the center of the Milky Way, dubbed Sagittarius A*.
“Our results should lead to a better understanding of the inner workings of AGNs. They could also help us better understand the history of the Milky Way, which harbors a supermassive black hole at its center that may have been active in the past”, concludes Gámez Rosas.
Pictured to the left is a view of the galaxy Messier 77 taken with the FORS2 instrument on ESO’s Very Large Telescope. On the right, we see the innermost region of this galaxy, its active galactic core.
Referencia: Violeta Gámez Rosas, Thermal imaging of dust hiding the black hole in NGC 1068, Nature (2022). DOI: 10.1038/s41586-021-04311-7. www.nature.com/articles/s41586-021-04311-7
