Black Holes & Co.
Black holes, neutron stars and supernovae: Flight into a black hole, the black hole in the center of the Milky Way, how many different kinds of black hole are there, how black holes light up their neighbourhood
This page features an overview of all our Spotlights dealing with black holes and other compact objects, notably neutron stars. Under the heading Close encounters with black holes, a Spotlight explores what an observer on a space-ship would see as, step by step, the ship approaches a black hole. The texts in the category How to track compact objects explores the phenomena that can be used by astronomers to track black holes and other compact objects in their telescopes, from their gravitational influence on neighbouring stars to the different ways that compact objects have of lighting up their immediate cosmic neighbourhood. The category The physics of black holes is dedicated to general theorems that have been proved about these objects. The category Physics in the background explores some physics that is useful for a better understanding of the Spotlights dealing with black holes and neutron stars.
Close encounters with black holes
How to track compact objects
More about the gravitational influence of black holes and neutron stars on their cosmic surroundings, from the orbits of nearby stars to accretion disks and the associated luminous phenomena.
Not only merging black holes, but also neutron star pairs emit gravitational waves.
During neutron star mergers, both gravitational wave and electromagnetic signals are emitted. This could help solve long-standing issues in basic physics research with multi-messenger astrophysics.
How the fact that black holes are very efficient in attracting surrounding matter leads to some of the most spectacularly luminous phenomena in the whole of the cosmos
Albert Einstein predicted their existence back in 1916, and on 14 September 2015 they were directly detected for the first time: Gravitational waves. Two large interferometric detectors of the LIGO Scientific Collaboration with major contributions from German researchers detected the signal known as “GW150914”. The waves originate from the merger of two black holes and are the first direct observation of these exotic objects.
The physics of black holes
In 2020, Roger Penrose was awarded half of the Nobel prize in physics for proving that black hole formation is a robust prediction of Einstein’s general theory of relativity.
Once they have settled down, there are actually only very few different kinds of black hole – find out which, and how black holes shed other distinguishing marks.
How, in one sense, space and time switch their roles inside a black hole – and why this leads to a black hole’s most characteristic property, namely that nothing can get out
Physics in the background
Some information about what is called the conservation of angular momentum, and its consequences for neutron stars, black holes and the matter disks around them