Quasars and active galactic nuclei (AGN) are likely powered by matter accretion onto a super-massive black hole located at their center. Before being swallowed by the black hole, matter spirals towards the center, while forming an accretion disc. Unfortunately, such a disc is too small so that one can in general solve it with present day telescopes. But the technique of radio interferometry with very long base (VLBI, with base length of the size of the earths radius) make it possible somehow. In some objects, very intense maser emission from small molecular clouds containing water vapor and probably related to the disc have been detected. From the rotation curve of the masing disc, one can deduce some of its properties (the disc mass, its size).
Jean-Marc Huré, from the Laboratory Universe and Theories (LUTH) at Observatory of Paris-Meudon and University Paris VII, comes to show that in galaxy NGC 1068, the accretion disc would have a mass comparable with that of the black hole (with about 9 million solar masses), and a size reaching one parsec (3 light-years). Such informations bring an additional proof that the discs of quasars and AGN are indeed gigantic systems.
Quasars were discovered at the end of the Sixties. They are, with their low luminosity analogues called "Active Galactic Nuclei" (or AGN), among the most luminous objects in the Universe. Today still, all the mechanisms which could release such a power are far from being understood. However, it seems rather well established that the matter accretion on a super-massive black hole is the key-process.
Jean-Pierre Luminet | alfa
Extremely close look at electron advances frontiers in particle physics
19.10.2018 | National Science Foundation
Blue phosphorus -- mapped and measured for the first time
16.10.2018 | Helmholtz-Zentrum Berlin für Materialien und Energie
Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz (Germany) together with scientists from Dresden, Leipzig, Sofia (Bulgaria) and Madrid (Spain) have now developed and characterized a novel, metal-organic material which displays electrical properties mimicking those of highly crystalline silicon. The material which can easily be fabricated at room temperature could serve as a replacement for expensive conventional inorganic materials used in optoelectronics.
Silicon, a so called semiconductor, is currently widely employed for the development of components such as solar cells, LEDs or computer chips. High purity...
Augsburg chemists present a new technology for compressing, storing and transporting highly volatile gases in porous frameworks/New prospects for gas-powered vehicles
Storage of highly volatile gases has always been a major technological challenge, not least for use in the automotive sector, for, for example, methane or...
When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way.
We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold...
Thin organic layers provide machines and equipment with new functions. They enable, for example, tiny energy recuperators. In future, these will be installed...
Das Zusammenspiel aus Struktur und Dynamik bestimmt die Funktion von Proteinen, den molekularen Werkzeugen der Zelle. Durch Fortschritte in der...
17.10.2018 | Event News
16.10.2018 | Event News
02.10.2018 | Event News
19.10.2018 | Earth Sciences
19.10.2018 | Life Sciences
19.10.2018 | Health and Medicine