Max Planck Institute for Radio Astronomy

New observations reveal how a powerful jet forms around a black hole

Large-scale observational campaign provides new insights into an assumed black hole binary at the centre of the active galaxy OJ 287

First detection of the heavy ¹⁸O isotope both in the upper and lower atmosphere of Earth

International team observes innermost structure of quasar 3C 273

Radio observations reveal a complex scenario for the interplay between star formation and the interstellar medium in Messier 33

Sitting deep in the heart of the Milky Way, it is 27,000 light years from Earth and resembles a donut: this is how the black hole at the center of our galaxy looks in the image obtained by researchers using the Event Horizon Telescope (EHT).

Centaurus is one of the most famous constellations in the southern sky. Take a closer look at the constellation through binoculars and you’ll see a pale nebula known as Centaurus A – it is in fact a distant galaxy in which a supermassive black hole resides. Michael Janssen from the Max Planck Institute for Radio Astronomy in Bonn and Radboud University Nijmegen led an Event Horizon Telescope team that has now come closer than ever before to understanding the nature of this gravity trap.

A cosmic lightning storm is playing out all around us. At any given moment, somewhere in the sky, a burst of radiation flashes and then fades away. Only observable with radio telescopes, these bursts last one-thousandth of a second and are one of astrophysics’ greatest mysteries. Scientists rather doubt this is evidence of warlike aliens fighting “star wars” in the vastness of space. Experts have named them “fast radio bursts” – but where do they come from?

Black holes swallow all light, making them invisible. That’s what you’d think anyway, but astronomers thankfully know that this isn’t quite the case. They are, in fact, surrounded by a glowing disc of gas, which makes them visible against this bright background, like a black cat on a white sofa. And that’s how the Event Horizon Telescope has now succeeded in taking the first picture of a black hole. Researchers from the Max Planck Institute for Radio Astronomy in Bonn and the Institute for Radio Astronomy in the Millimeter Range (IRAM) in Grenoble, France, were among those making the observations.

Pulsars are the most compact material objects in the universe. Their diameter is approximately equal to that of the city of Munich, but they contain the mass of the Sun. These extreme conditions make them ideal test objects for the theory of general relativity, as the work of Michael Kramer and his colleagues from the Bonn-based Max Planck Institute for Radio Astronomy shows.

2021 marked the fiftieth anniversary of the inauguration of the radio telescope in Effelsberg. In the past decades, the telescope, whose construction broke new technical ground, has produced numerous important observational results. Thanks to constant improvements and renewals it is still state-of-the-art. Selected current observational projects are presented here.

Extremely precise measurements of the motion of a fast-spinning pulsar in a triple star system provide one of the strongest tests ever of a simple, but fundamental prediction of general relativity: that gravity affects all objects with the same acceleration, without regard for their composition, density or the strength of their own gravitational field. General relativity has again survived this test, one of the most stringent ever, which strongly constrains many alternative theories of gravity.

On April 10, 2019, the first image of a black hole was published by a team of 347 international scientists from 59 institutes in 18 countries. Theoretical work and indirect evidence for the existence of black holes has been around for a long time. Only now did the observations provide the necessary resolution for an image made possible by a combination of seven radio telescopes scattered across the Earth, observing the centre of the galaxy M87. More than 30 scientists and engineers of the Max Planck Institute for Radio Astronomy in Bonn are involved in this success.

The airborne observatory SOFIA allows astronomical observations in the Far-Infrared, which is not accessible from the ground.  It covers the most important cooling lines of the interstellar medium. Velocity-resolved observations of these lines are crucial for our understanding of the star formation process. Here we present observations of the ionized carbon finestructure line in the Lagoon Nebula, which for the first time reveals the gas motions in the immediate environment of the nebula.

The formation of relativistic jets in active galaxies is a poorly understood physical process. Providing observational constraints for theoretical models is a crucial but challenging task, since it requires the imaging of emission regions in the immediate proximity of the black hole. We have observed the prototype radio galaxy Cygnus A through very-long-baseline interferometry at millimeter wavelengths, and obtained a sharp view of the jet base. Our analysis of the jet kinematic properties and internal structure suggests that the jet of Cygnus A is a disk wind accelerated by magnetic fields.