Science

Find below some of my science highlights. For those willing to take the risk, you can dive into the full published list on the Science Explorer.

The shadow of the supermassive black hole at the center of M87, observed in 2017, 2018 and 2021. The streamlines indicate the direction of the electric field vector.
Credit: Event Horizon Telescope Collaboration, 2025

The many faces of a supermassive black hole

In a multi-year analysis, the Event Horizon Telescope Collaboration uncovers the changing appearance of the ring-like radio emission around the supermassive black hole at the heart of M87. Utilizing data from the 2017, 2018 and 2021 observation campaigns, the image structure evidently undergoes significant changes. The position angle of the peak brightness moves along the ring, and the polarization pattern (streamlines on the images) indicates changes in the magnetic field geometry. These effects could be attributed to magneto-hydrodynamic turbulence in the plasma flow.

The cosmic beacon of M87

Supermassive black holes at the centers of galaxies are known to produce relativistic jets - highly collimated beams of magnetized plasma, reaching thousands of light years into interstellar space. The jet emanating from the center of galaxy M87, discovered more than a century ago, is the best studied such object in the sky. Now, the James Webb Space Telescope revealed new details of the jet's and counter-jet's intricate structures.

You can find the article in Astronomy & Astrophysics.

JWST NIRCam RGB image of M87 and its jet created using three wavelength filters.
Image credit: J. Röder/M. Wielgus, 2025

Schematic view of an AGN. From close to the black hole, relativistic jets are launched, starting off with a parabolic geometry and later transitioning to a conical appearance.
Image credit: J. Röder/M. Wielgus, 2025

Relativistic jets with the Event Horizon Telescope

Alongside the two supermassive black holes in M87 and Sgr A*, the Event Horizon Telescope (EHT) observed a total of sixteen such "active galactic nuclei" (AGN) in 2017. Despite the small sample, a clear deviation from established models of jets was found, requiring acceleration or changes in geometry to explain the observations.

Read more in Astronomy & Astrophysics.

Up around the bend

The quasar 3C345 is a key observing target for the science of active galactic nuclei. Features in the highly bent compact jet, seen in radio wavelengths, appear to move super-luminally on non-ballistic paths. This study follows up on previous works investigating the interplay of features in the jet, and their connection to the frequent gamma-ray outbursts of the source.

The research is published in Astronomy & Astrophysics.

Artist's impression of a supermassive black hole surrounded by an accretion disk, powering a quasar jet.
Image credit: ESO/M. Kornmesser

General relativistic magneto-hydrodynamic simulation of the plasma flow around a dilaton black hole, post-processed using general relativistic radiative transfer calculations.
Image credit: J. Röder/Y. Mizuno, 2025

An exotic mass monster

In a computer simulation, hot gas swirls around an unusual compact object: a "dilaton" black hole. Derived from string theory, its appearance resembles that of a "regular" black hole out of Einstein's theory of general relativity. Taking different scenarios for the radiation mechanism and the accretion of matter onto the black hole into account, it is evident that direct imaging has little chances as a test for general relativity.

This study is published in Astronomy & Astrophysics.

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