A three-dimensional (3D) map of the universe has been unveiled, allowing us to see millions of galaxies at a glance, even if we are capturing light from 11 billion years ago.
The Dark Energy Spectroscopic Instrument (DESI) is a massive international project to create a 3D universe map to reveal the identity of dark energy, which constitutes most of the universe’s total energy.
About 900 researchers from 70 institutions across 11 countries, including South Korea, participated in this project. They are using a telescope equipped with a multi-channel spectrometer, composed of 5,000 small fiber-optic robots, located at the summit of Kitt Peak in Arizona, USA. This setup allows them to accurately observe the light spectrum from distant galaxies and study dark energy.
An international research team, which includes the Korea Astronomy and Space Science Institute, has released the largest-ever 3D map of the universe as the first achievement of the DESI project.
Over the past year, the research team has used DESI to observe the light from galaxies and quasars up to 11 billion light years away from Earth, and it has also measured how fast the universe has expanded.
For the first time in the history of the early universe, the team has measured the entire history of the universe’s expansion with an error range of 0.5%, from 8 to 11 billion years ago, and has been accurately measured with an error of less than 1%.
In the early universe, scattered baryons appear as Baryon Acoustic Oscillations (BAO), creating high-density regions along the spherical surface of the early universe plasma, much like ripples caused by throwing a stone into a pond.
By measuring how the BAO radius has changed at seven different times, using the fact that this pattern expands with the universe, the team has reconstructed the history of the universe’s evolution.
The research team combined data from DESI observations, cosmic background radiation, and supernovae to conclude that there is a more than 95% chance that dark energy is not fixed but changes over time.
The DESI research team plans to create a map of the universe featuring 3 million quasars and 37 million galaxies.
Lee Hyung Mok, the head of the Gravitational Wave Universe Research Group and a professor at the Department of Physics and Astronomy at Seoul National University, explained that the results of DESI are the most accurate analysis of the history of the early universe on the largest-ever 3D scale.
Dr. Shafieloo Arman of the Korea Astronomy and Space Science Institute said, “Through the DESI project, we discovered a high probability that the characteristics of dark energy change over time. We expect this observational data to play a crucial role in verifying various theories about the universe’s expansion and gravity and clarifying the nature of dark energy.”
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