![]() Īt the risk of anticipating results and concepts that will be developed only later in this review, in the following we try to give simple answers to two frequently asked questions: 1) why should one expect any interesting new dynamics in higher-dimensional general relativity, and 2) what are the main obstacles to a direct generalization of the four-dimensional techniques and results. Arguably, two advances are largely responsible for this perception: the discovery of dynamical instabilities in extended black-hole horizons and the discovery of black-hole solutions with horizons of nonspherical topology that are not fully characterized by their conserved charges. There is a growing awareness that the physics of higher-dimensional black holes can be markedly different, and much richer, than in four dimensions. At the very least, this study will lead to a deeper understanding of classical black holes and of what spacetime can do at its most extreme. One would like to know which of these are peculiar to four-dimensions, and which hold more generally. ![]() ![]() For instance, four-dimensional black holes are known to have a number of remarkable features, such as uniqueness, spherical topology, dynamical stability, and to satisfy a set of simple laws - the laws of black hole mechanics. Just as the study of quantum field theories, with a field content very different than any conceivable extension of the Standard Model, has been a very useful endeavor, throwing light on general features of quantum fields, we believe that endowing general relativity with a tunable parameter - namely the spacetime dimensionality d - should also lead to valuable insights into the nature of the theory, in particular into its most basic objects: black holes. These, however, refer to applications of the subject - important though they are - but we believe that higher-dimensional gravity is also of intrinsic interest. Nature Astronomy, 10 februari 2022.As mathematical objects, black-hole spacetimes are among the most important Lorentzian Ricci-flat manifolds in any dimension. Wagner, Tom Oosterloo, Pierre Guillard, Dipanjan Mukherjee en Geoffrey Bicknell: Cold gas removal from the centre of a galaxy by a low-luminosity jet. Referentie: Suma Murthy, Raffaella Morganti, Alexander Y. She now works as a postdoc at JIVE, the European institute in Dwingeloo that, among other things, coordinates the cooperation of radio telescopes all over the world. Murthy defended her PhD thesis at the University of Groningen on 8 February. The observations by Murthy and her colleagues had previously been predicted by computer simulations. It is a collection of radio dishes in the French Alps at an altitude of about 2500 metres. NOEMA stands for Northern Extended Millimetre Array. The researchers made their observations in October and November 2020 with the NOEMA telescopes. From now on, we will have to take this into account in models for the evolution of galaxies." Our results show that these relatively weak radio-emitters can indeed inhibit growth. It was thought that they did not play an important role in growth inhibition. "A large part of the radio emitters are relatively quiet. "That low-power radio jets have also been found to clean a galaxy is extraordinary," says principal investigator Suma Murthy (working at ASTRON and at the Kapteyn Institute of the University of Groningen during the research).
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