The black holes at the centers of galaxies are the most mysterious objects in the Universe, not only because of the huge quantities of material within them, millions of times the mass of the Sun, but because of the incredibly dense concentration of matter in a volume no bigger than that of our Solar System. When they capture matter from their surroundings they become active, and can send out enormous quantities of energy from the capture process, although it is not easy to detect the black holeA black hole is a place in space where the pull of gravity is so strong not even light can escape it. Astronomers classify black holes into three categories by size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass smaller than our Sun and supermassive black holes could have a mass equivalent to billions of our Sun.”>black hole during these capture episodes, which are not frequent.
However, a study led by the researcher Almudena Prieto, of the Instituto de Astrofísica de Canarias (IAC), has discovered long narrow dust filaments which surround and feed these black holes in the centers of galaxies, and which could be the natural cause of the darkening of the centers of many galaxies when their nuclear black holes are active. The results of this study have recently been published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).
Using images from the Hubble Space TelescopeThe Hubble Space Telescope (often referred to as Hubble or HST) is one of NASA’s Great Observatories and was launched into low Earth orbit in 1990. It is one of the largest and most versatile space telescopes in use and features a 2.4-meter mirror and four main instruments that observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. It was named after astronomer Edwin Hubble.”>Hubble Space Telescope, the Very Large TelescopeThe Very Large Telescope array (VLT) is a visible and infrared wavelength telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors of 8.2m diameter and four movable 1.8m diameter Auxiliary Telescopes.”>Very Large Telescope (VLT) at the European Southern Observatory (ESOCreated in 1962, the European Southern Observatory (ESO), is a 16-nation intergovernmental research organization for ground-based astronomy. Its formal name is the European Organisation for Astronomical Research in the Southern Hemisphere.”>ESO), and the Atacama Large Millimetre Array (ALMAThe Atacama Large Millimeter/submillimeter Array (ALMA) is the largest ground-based facility for observations in the millimeter/submillimeter regime in the world. ALMA comprises of 66 high-precision dish antennas of measuring either 12 meters across or 7 meters across and is an international partnership between Europe, the United States, Japan and the Republic of Chile. “>ALMA) in Chile, the scientists have been able to obtain a direct visualization of the process of nuclear feeding of a black hole in the galaxy NGC 1566 by these filaments. The combined images show a snapshot in which one can see how the dust filaments separate, and then go directly towards the center of the galaxy, where they circulate and rotate in a spiral around the black hole before being swallowed by it.
“This group of telescopes has given us a completely new perspective of a supermassive black hole, thanks to the imaging at high angular resolution and the panoramic visualization of its surroundings, because it lets us follow the disappearance of the dust filaments as they fall into the black hole,” explains Almudena Prieto, the first author on the paper.
The study is the result of the long-term PARSEC project of the IAC, which aims to understand how supermassive black holes wake up from their long lives of hibernation, and after a process in which they accrete material from their surroundings, they become the most powerful objects in the Universe.
Reference: “Dust in the central parsecs of unobscured AGN: more challenges to the torus” by M. Almudena Prieto, Jakub Nadolny, Juan A. Fernández-Ontiveros and Mar Mezcua, 16 June 2021, Monthly Notices of the Royal Astronomical Society.
Part of this work was carried out within the Master’s thesis in Astrophysics of the University of La Laguna of Jakub Nadolny, carried out at the IAC within the PARSEC project. Researchers Mar Mezcua and Juan A. Fernández Ontiveros were also advisers to this work, while they had PARSEC postdoctoral contracts at the IAC.