REWARD · Reflection in warped accretion disks around black holes

Reflection in warped accretion disks around black holes

Black holes are among the most fascinating and extreme objects in the universe. They are formed when stars collapse at the end of their lives or lie at the centres of galaxies, where they can reach masses billions of times larger than the Sun. Despite being invisible, black holes profoundly shape their surroundings. On a small scale, they help us understand how stars live and die. On a large scale, they regulate the growth of galaxies and influence the structure of the universe itself. Understanding black holes is therefore central to answering some of the biggest questions in modern astrophysics: How do galaxies evolve? How do stars end their lives? Do the laws of physics, as described by Einstein’s theory of relativity, hold true under the most extreme conditions in the cosmos? To make progress, scientists need to measure black holes more accurately. In particular, two key properties — their mass and their rate of rotation (spin) — are essential to connect theory with observations. The main obstacle lies in the complex environment around black holes. Matter falling into them forms a disk of gas and, in many cases, powerful jets. But the exact shape and structure of these regions are still debated, and without this knowledge, current methods of measuring black hole properties remain uncertain. A major breakthrough has recently become possible thanks to new space missions. For the first time, scientists can now measure the polarisation of X-ray radiations emitted by these objects — a property of light that is highly sensitive to geometry. In combination with radio observations of jets and with data from other telescopes, this opens up an unprecedented opportunity to reveal the structure of matter around black holes and to refine fundamental measurements. The REWARD project was created to seize this opportunity. Its overall objective is to combine these new X-ray polarisation data with multiwavelength observations in order to clarify the geometry of the regions closest to black holes. At the same time, the project aims to build a broader picture of how black hole systems behave, avoiding the risk of drawing conclusions from only a few well-studied cases. In this way, REWARD is not only advancing our knowledge of some of the most extreme objects in the universe, but also strengthening Europe’s role in a highly competitive area of space science. By aligning with recent international investments in new observatories, the project contributes to maximising the scientific return of these missions and prepares the ground for the next generation of astrophysical discoveries.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз