Osaka University | 2018 Apr 24
As science enthusiasts around the world bid farewell to legendary cosmologist Stephen Hawking, researchers continue to make important discoveries about the evolution of galaxy clusters that capture the imagination.
Now, an international collaboration between Yutaka Fujita at Osaka University and researchers from Taiwan, Italy, Japan, and the United States found a new fundamental law that stipulates the evolution of galaxy clusters. ...
Galaxy clusters are the largest celestial body in the universe. However, it has been difficult to measure their size and mass accurately because they mainly consist of dark matter that we cannot observe directly. One way to observe the dark matter indirectly is to use the gravitational lensing effect based on Einstein’s theory of relativity. Light rays from a galaxy behind a cluster are pulled by the gravity of the cluster as they pass through it, and their paths are bent. This is exactly the same effect as a lens, focusing the light of the distant galaxy and distorting its shape. If we can measure the distortion of the shape for many background galaxies, we can reveal the gravitational field of the cluster, and as a result, we can accurately measure its size and mass. ...
Combining with gas temperature data from the Chandra X-ray satellite, the research group statistically examined those latest data and found that they conform to a simple law represented only by the size, mass, and gas temperature of clusters. Moreover, by making full use of computer simulations, they showed that clusters have grown over 4 to 8 billion years according to the law. Theoretically, the law means that those gigantic clusters are still in adolescence, growing by drawing a large amount of surrounding substances with their strong gravity. ...
Discovery of a New Fundamental Plane Dictating Galaxy Cluster Evolution from Gravitational Lensing - Yutaka Fujita et al
- Astrophysical Journal 857(2):118 (2018 Apr 20) DOI: 10.3847/1538-4357/aab8fd
arXiv.org > astro-ph > arXiv:1801.03943 > 11 Jan 2018 (v1), 20 Mar 2018 (v3)