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
23.01.2018 | Physikalisch-Technische Bundesanstalt (PTB)
New for three types of extreme-energy space particles: Theory shows unified origin
23.01.2018 | Penn State
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
23.01.2018 | Life Sciences
23.01.2018 | Earth Sciences
23.01.2018 | Physics and Astronomy