Until today, precise observations and analyses of the cosmic microwave background (CMB) and large-scale structures (LSS) have established the standard framework of the universe, the so-called CDM model, in which cold dark matter (CDM) and dark energy (cosmological constants) are important features.
The model holds that primordial fluctuations were created at the beginning or early of the universe, and that it served as a trigger that led to the creation of everything in the universe, including stars, galaxies, galaxy clusters, and their spatial distribution throughout space.
Although they are very small when generated, due to gravity, the fluctuations increase over time, eventually forming dense areas of dark matter, or halos. The different halos then repeatedly collide and merge with each other, resulting in the formation of celestial bodies such as galaxies.
Since the nature of the spatial distribution of galaxies is strongly influenced by the nature of the original fluctuations that originally produced them, statistical analysis of the distribution of galaxies is actively carried out to explore the nature of the original fluctuations.
In addition to this, the spatial pattern of galaxy shapes distributed over a vast area of the universe also reflects the nature of the underlying primitive fluctuations.
However, conventional analysis of large-scale structures only focuses on the spatial distribution of galaxies as points. Recently, researchers have begun to study galaxy shapes because it provides not only additional information, but also a different perspective on the nature of the original waves.
By Toshiki Kurita, then a graduate student at the Kavri Institute for Cosmophysics and Mathematics (K**li IPMU) (currently a postdoctoral researcher at the Max Planck Institute for Astrophysics) and Masahiro Takada, a professor at the Kavri Institute for Cosmophysics and Mathematics (K**li IPMU). Takada) led a research team that has developed a method to measure galaxy shape power spectra that extracts key statistics from galaxy shape patterns by combining spectral data from the spatial distribution of galaxies and imaging data of individual galaxy shapes.
As a result, they succeeded in limiting the statistical properties of primitive fluctuations, which laid the foundation for the formation of the entire structure of the universe.
They found that the directions of the shapes of the two galaxies, which are more than 100 million light-years apart, are statistically remarkably consistent. Their results suggest that there is a correlation between distant galaxies, and that the process of their formation is apparently independent and causally uncorrelated.
In this study, we were able to impose limits on the nature of primordial fluctuations by statistically analyzing the 'shapes' of numerous galaxies obtained from large-scale structural data. There are few research precedents for using the shape of galaxies to explore. The physics of the early universe and the process of its research, from the construction of ideas, the development of analytical methods to the actual analysis of data, was a series of trial and error.
As a result, I faced many challenges. But I am happy to be able to complete these challenges during my PhD program. I believe this achievement will be the first step in opening up a new field of study in cosmology using the shape of galaxies," Kurita said.
In addition, a detailed study of these correlations confirms that they are consistent with inflation** and do not exhibit the non-Gaussian characteristics of the original fluctuations.
This research is the result of Dr. Toshiki**. This is an excellent research result, and we have developed a method to validate cosmological models using galaxy shapes and galaxy distributions, apply them to the data, and then test inflation physics. No one has done research before on a research topic, but he did all three steps: theory, measurement, and application. Congratulations!I'm very proud that we were able to complete all three steps. “
"The new physics of detecting swelling is a great discovery, but we have pointed the way for future research," Takada said. We anticipate opening up more research areas with the Subaru Prime Focus spectrometer." ”
The methodology and results of this study will allow researchers to further test inflation theories in the future.