Astronomers have finally confirmed a theory related to Active Galactic Nuclei (AGNs), the central region of galaxies that are a higher luminosity than expected. Observations of AGNs have them placed into two groups: Type 1 and Type 2. Researchers have always assumed that the difference is just about the angle we are looking at them from and nothing else. A new discovery has finally provided crucial evidence in support of it.
AGNs are powered by supermassive black holes snacking on material falling towards them. If we can see the feeding process directly, they are classified as type 1. However, there are others in which a thick donut of gas and dust obscure this process. These are type 2.
The unification model requires showing that behind a type 2, there is really a type 1, without having to travel for millions of light-years and observe a galaxy from another angle.
As reported in the journal Nature, observations from the Very Large Telescope Interferometer VLTI) have done just that. Astronomers have observed a galaxy known as Messier 77 (or NGC 1068) which is the archetypal Type 2 AGN. Detailed thermal maps of the core of this cosmic island of stars showed that the supermassive black hole is there, hiding behind a thick blanket of dust.
“The real nature of the dust clouds and their role in both feeding the black hole and determining how it looks when viewed from Earth have been central questions in AGN studies over the last three decades,” lead author Violeta Gámez Rosas from Leiden University, said in a statement. “Whilst no single result will settle all the questions we have, we have taken a major step in understanding how AGNs work.”
Despite being in the vacuum of space, the dust around the black hole tends to have temperatures between room temperature and over one thousand degrees. As stuff spirals inwards, the incredible gravitational pull heats up that material to incredible levels. In turn, the dust blocking our view absorbs some of that powerful light becoming hotter.
That’s what the team was able to track out with the MATISSE instrument on the VLTI, owned by the European Southern Observatory (ESO) consortium. Combined with radio maps from the Atacama Large Millimeter/submillimeter Array, co-owned by ESO, and the National Radio Astronomy Observatory’s Very Long Baseline Array.
“Messier 77 is an important prototype AGN and a wonderful motivation to expand our observing programme and to optimise MATISSE to tackle a wider sample of AGNs," Team member Bruno Lopez, the MATISSE Principal Investigator at the Observatoire de la Côte d’Azur in Nice, added.
This and future work will hopefully lead to a better understanding of what makes AGNs tick. Messier 77 is located 47 million light-years away.