A super-massive black hole acts like a lurking "monster" at the centre of the galaxy which swallows the surrounding material through the intensity of its gravitational pull.
X-ray observations indicate that a large amount of energy is produced by the in-fall of matter into a black hole, and ejected in powerful jets. Astronomers from the Max Planck Institute for Extraterrestrial Physics have now shown that these jets eject matter not only from their host galaxies but even the gas between the galaxy group members. (Astrophysical Journal, May 1st 2010)
Astronomers have long been trying to understand how black holes interact with the environment (the so-called feedback), but to date the process is poorly understood. Observations and simulations have shown that active galaxies transport huge amounts of material with their jets, which are particularly luminous at radio wavelengths, into the intra-cluster gas. Signatures of this "radio-mode feedback" are observed both in radio and in X-rays.
Recent studies have shown that the amount of gas in galaxy groups, objects consisting of several galaxies bound together such as the Milky Way and the Andromeda Galaxy, does not add up to the amount predicted by cosmology - unlike in galaxy clusters with up to thousands of individual members. Large amounts of mechanical energy injected into the gas from the central black hole may have removed part of it. However to date this was only a hypothesis. Previous group samples were limited to a handful of nearby objects populated by low luminosity radio black holes.
Using one of the largest samples of X-ray detected groups and clusters of galaxies identified by XMM-Newton together with radio observations, a team of astronomers led by Stefania Giodini at the Max Planck Institute for Extraterrestrial Physics has studied the energetics of radio galaxy feedback in galaxy groups. In the COSMOS field, where almost 300 X-ray galaxy groups have been detected, the team has been able to show that the black hole activity in the centre of galaxy groups must have a dramatic effect on the surroundings: they eject sufficient energy to blow the intergalactic gas out of the gravitational well of the galaxy group. The mystery of the missing gas in galaxy groups is solved - and the large impact of black holes in galaxy groups demonstrated for the first time.
"In galaxy groups the gas is contained by gravity. But the black holes produce so much energy that this outweighs the capacity of the group to hold its gas," explained Stefania Giodini, the lead author of the paper. "A significant part of the gas is removed. No similar effect is observed in more massive galaxy clusters, where the huge gravitational pull restrains the gas from being removed."
"It is impressive what a significant influence radio outflows from galaxies can have on their surroundings," said Vernesa Smolèiæ from the California Institute of Technology, co-author of the paper. "This likely happens not only on the scales of the host galaxies of these outflows, but also on scales as large as the distance from our Milky Way to Andromeda. Radio galaxies seem to be the "trouble makers" in the Universe that can heat the gas around their host galaxies to unexpected temperatures, as well as expel a fraction of matter from galaxy groups."
Hans Böhringer, head of the Research Group for Clusters of Galaxies and Cosmology at the Max Planck Institute for Extraterrestrial Physics, also participated to this study: "In nearby clusters we can see the short term effect of the energy outbursts occasionally in the form of radio-luminous, relativistic plasma bubbles. Direct evidence for periodic outburst behaviour can only be found by looking at their effect in a large number of groups."
The enormous effect of individual galaxy nuclei is surprising even for astronomers. "I could never imagine to what a degree the black holes can displace the gas in galaxy groups," says Alexis Finoguenov from the Max Planck Institute for Extraterrestrial Physics and University of Maryland, Baltimore County, "they are the glass-blowers of the Universe".
S. Giodini, V. Smolèiæ, A. Finoguenov, H. Boehringer, L. Bîrzan, G. Zamorani, A. Oklopèiæ, D. Pierini, G.W. Pratt, E. Schinnerer, R. Massey, A.M. Koekemoer, M. Salvato , D.B. Sanders, J. S. Kartaltepe, D. Thompson
Radio Galaxy Feedback in X-Ray Selected Groups from COSMOS: The Effect on the ICM
The Astrophysical Journal, 714, 218, May 1st 2010
Dr. Hannelore Hämmerle | EurekAlert!
When helium behaves like a black hole
22.03.2017 | University of Vermont
Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
22.03.2017 | International Centre for Radio Astronomy Research
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
22.03.2017 | Materials Sciences
22.03.2017 | Physics and Astronomy
22.03.2017 | Materials Sciences