An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports a study on the feeding process of the supermassive black hole at the center of the galaxy NGC 1566. A team of researchers led by Almudena Prieto of the Instituto de Astrofísica de Canarias (IAC) used observations conducted with the Hubble Space Telescope, the VLT, and the ALMA radio telescope in Chile to be able to visualize filaments of interstellar dust that separate and subsequently head towards the supermassive black hole, approaching it in a spiral trajectory that eventually leads them to be swallowed. Those filaments could obscure the center of many galaxies with active galactic nuclei.

NGC 1566 is a spiral galaxy whose distance from Earth has been the subject of several measurement attempts that offered very different estimates. At its center is a supermassive black hole that has an estimated mass of 13 million times the Sun’s surrounded by huge amounts of materials. They’re heated to the point of generating strong electromagnetic emissions and for this reason, we speak of an active galactic nucleus. The processes taking place in active galactic nuclei such as the one in NGC 1566 have become the subject of many studies because they’re really extreme environments.

The study conducted by Almudena Prieto’s team is part of the PARSEC project to investigate the central parsec of the nearest galaxies by spanning the electromagnetic spectrum thanks to various instruments capable of detecting emissions in the various bands. The study of the galaxy NGC 1566 offers new insights into how the supermassive black hole feeds.

To achieve the desired results, the researchers combined observations from very different instruments: the Hubble Space Telescope, the VLT (Very Large Telescope) in Chile, and the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, also in Chile. They made it possible to observe dust filaments around the supermassive black hole at the center of the galaxy NGC 1566 and their movements. These are long and narrow filaments that separate and then end up in a spiral trajectory that dooms them.

The top image (Courtesy ESO) shows the process that was called nuclear feeding of the galaxy NGC 1566’s supermassive black hole. Filaments of dust surround the galactic nucleus and are placed in a spiral trajectory that leads to them being swallowed.

In the galaxy NGC 1566’s case, the filaments take on a shape called a torus around the supermassive black hole with a thickness that can’t obscure the nucleus. The researchers believe the position of the filaments can be an important factor in determining if they can obscure the nucleus. NGC 1566 is one of several galaxies under study and the comparison with observations of other active galactic nuclei will be very useful for understanding those behaviors, including the processes that lead nuclei to become active after millions of years.