The weak radiation has been discovered by the H.E.S.S. telescopes in Namibia, currently one of the most sensitive instruments of high-energy astrophysics. (The Astrophysical Journal Letters 695, L40-L44, 2009)
Active galactic nuclei are the most energetic objects in the Universe. Around the suspected supermassive black hole they harbour at their centre, charged particles (electrons and protons) may be accelerated to velocities close to the speed of light and ejected in oppositely directed jets. Centaurus A, located in the constellation Centaurus, is one of the brightest galaxies in the night sky and the nearest radiogalaxy with an active nucleus. Its proximity enables unique studies of the active centre and its surrounding. Centaurus A covers an area of the sky more than 100 times the size of the area of the full moon - but this extended structure only glows in radio frequencies with only the host galaxy being visible to the naked eye.
The telescopes of the High Energy Stereoscopic System (H.E.S.S.) in Namibia have now, for the first time, observed very-high-energy gamma-ray emission from Centaurus A. H.E.S.S. consists of four identical telescopes with 13 m mirror diameter and is operated by an international collaboration, coordinated by the Max-Planck-Institut für Kernphysik in Heidelberg. Ultrafast cameras record the weak blue flashes that arise when very-high-energy gamma-ray photons are absorbed in the atmosphere and create cascades of subatomic particles, so-called particle showers.
The high-energy gamma radiation from Centaurus A is so weak that more than 100 hours of observation time were needed to obtain a picture. The detected emission originates from the centre of the galaxy and the inner parts of the jets. With the current data, however, it is not yet possible to identify the exact origin of the emission. These gamma rays - a trillion times more energetic than visible light - are produced, it is thought, when particles, accelerated to extreme energies in the vicinity of a black hole, interact with radiation fields or the surrounding medium.
The detection of very-high-energy gamma rays from Centaurus A poses the more general question of whether such emission might be a common feature of active galactic nuclei. To answer this question, further observations of Centaurus A and of other active galactic nuclei are necessary. In that case, future instruments with higher sensitivity will be able to detect many more sources than previously anticipated and so better determine the processes involved.
A very large telescope with a mirror diameter of 30 m to extend the H.E.S.S. experiment is already under construction and will start observation in 2010. For the future, the European project Cherenkov Telescope Array (CTA) is planned. This gamma-ray observatory will consist of roughly 100 telescopes, leading to an improvement in sensitivity by a factor 10 compared to the current generation of instruments.
Contact:Dr. Martin Raue
http://www.mpifr-bonn.mpg.de/public/pr/pic-cena-dt.html MPIfR, Bonn, press information about the image
Dr. Bernold Feuerstein | Max-Planck-Institut
Further reports about: > Active galactic nuclei > Centaurus A > High Energy Stereoscopic System > Kernphysik > black hole > electrons > galactic nucleus > gamma light > gamma-ray observatory > high-energy astrophysics > high-energy gamma radiation > protons > radio galaxy shining > radiogalaxy > subatomic particles > supermassive black hole > telescopes > very-high-energy gamma radiation
Water without windows: Capturing water vapor inside an electron microscope
13.12.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University
Columbia engineers create artificial graphene in a nanofabricated semiconductor structure
13.12.2017 | Columbia University School of Engineering and Applied Science
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
13.12.2017 | Health and Medicine
13.12.2017 | Physics and Astronomy
13.12.2017 | Life Sciences