Delivery time2023-10-04 10:10
U.S. research team: “Giant galaxies in the early universe appear large not because they have large masses, but because of the glare.”
(Seoul = Yonhap News) Reporter Jooyoung Lee = The giant galaxies hundreds of millions of years after the Big Bang discovered in early observations by the James Webb Space Telescope (JWST) are not actually huge, but appear bright due to the flash of stars explosively forming in young galaxies. The research results are out.
An illustration of a young galaxy in the early universe, brightly lit by explosive star formation.
An image of a young galaxy in the early universe reconstructed from simulation data. The research team explained that the giant galaxies discovered hundreds of millions of years after the Big Bang, discovered in early observations by the James Webb Space Telescope (JWST), are not actually huge, but appear bright due to the flash of stars explosively formed in young galaxies. Stars and galaxies are shown as bright white dots, while diffuse dark matter and gas are shown in purple and red. [Aaron M. Geller, Northwestern, CIERA+IT-RCDS 제공. 재판매 및 DB 금지]
On the 4th, the team of Dr. Claude-André Faucher-Guyger of Northwestern University announced in the scientific journal ‘Astrophysical Journal Letters’ that they came to this conclusion by using the latest computer simulation to model how galaxies were formed immediately after the Big Bang.
The James Webb Telescope, currently the most advanced astronomical observation equipment possessed by mankind, discovered six giant galaxies with a total mass of 10 to 100 billion times that of the Sun in young galaxies only 600 million years after the Big Bang in its initial observations, and reported this to the academic world. It was shocking.
Some scientists have raised the need to revise the standard model of existing cosmology, saying that such a young galaxy is too bright and massive to be considered formed immediately after the Big Bang, which is like a newborn baby growing into an adult in just a few years.
“It was a big surprise because these galaxies in the early universe were much brighter than expected,” said Dr. Faucher-Giger. “I saw it,” he said.
In this study, the research team used the ‘Relativistic Environmental Feedback’ (FIRE) simulation, a joint project of Northwestern University, California Institute of Technology (CalTech), Princeton University, and the University of California, San Diego (UC San Diego), to model the galaxy formation process in the early universe. .
Flatiron Institute Computational Astrophysics Center, Massachusetts Institute of Technology (MIT), and University of California, Davis (UC Davis) participated as co-researchers in this study.
FIRE simulations combine astrophysics theory and the latest algorithms to model galaxy formation. Through this, we can investigate how galaxies form, grow, and change shape, and explain the energy, mass, momentum, and chemical elements returned from stars. there is.
Six giant galaxies 500 to 800 million years after the Big Bang
The red circles in each photo are giant galaxies 500 to 800 million years after the Big Bang. The galaxy on the left in the bottom row currently has the same number of stars as the Milky Way, but its star density is estimated to be 30 times higher. [NASA, ESA, CSA, I. Labbe (Swinburne University of Technology) 제공. 재판매 및 DB 금지]
Through simulations, the research team discovered that giant galaxies in the early universe can shine brightly like giant galaxies without actually having that much mass.
The brightness of a galaxy is usually determined by its mass, but the bright galaxies discovered by JWST do not have that much mass, but can shine brightly like giant galaxies due to stars that form irregularly and explosively.
As a result of a simulation modeling the early universe, it was found that in young galaxies, stars do not form at a constant rate but instead undergo ‘bursty star formation’, which rapidly increases in a short period of time.
The research team said that in explosive star formation, many stars form at once, then star formation becomes very small for millions of years, and then many stars form again, and the pattern repeats. Because of the flashes emitted from the explosively formed stars, the galaxy will shine much brighter compared to its mass. explained that it can be done.
In addition, as a result of predicting the number of bright galaxies that could exist at the dawn of the universe through simulation, it was found that it actually matched the number of bright galaxies observed by JWST.
Dr Faucher-Giger said: “This study not only explains why young galaxies in the early universe appear incredibly massive, but also shows that the standard model of existing cosmology should have no problem achieving this level of brightness by the dawn of the universe. “It shows,” he said.
“Explosive star formation often occurs in low-mass galaxies, but the reason is still a topic of research,” he said. “It forms a cycle in which the star formed explosively explodes as a supernova millions of years later and the gas becomes a new star again.” “I can see it,” he added.
◆ 출처 : Astrophysical Journal Letters, Claude-Andre Faucher-Giguere et al., ‘Bursty star formation naturally explains the abundance of bright galaxies at cosmic dawn’,
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2023/10/04 10:10 Sent
