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Galaxies falling into a massive galaxy cluster. Upon entering the group, these galaxies exhibit a blue shift compared to the central galaxy. Credit: Dr. Shihong Liao
A study using data from the Sloan Digital Sky Survey reveals that the Universe may be younger than estimated, challenging conventional cosmological models by analyzing the movements of satellite galaxies around massive clusters.
In standard cosmological models, the formation of cosmological structures begins with the emergence of small structures, which subsequently undergo hierarchical fusion, leading to the formation of larger systems. As the Universe ages, massive galaxy groups and clusters, which are the largest systems, tend to increase in mass and reach a more dynamically relaxed state.
The movements of satellite galaxies around these groups and clusters provide valuable information about their state of assembly. Observations of such motion offer crucial clues about the age of the Universe.
Using public data from the Sloan Digital Sky Survey (SDSS), a research team led by Professor Qi Guo of the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) analyzed the kinematics of pairs of satellites around clusters of massive galaxies. The team’s findings suggest that the Universe may be younger than predicted by the LCDM model with Planck cosmological parameters.
This study was published in Nature Astronomy on January 22.
The cumulative fraction of correlated pairs as a function of tolerance angle. Credit: Dr. Qing Gu
The researchers studied the motion of pairs of satellites located on the opposite side of massive galaxy groups using their velocity offsets from the central galaxy along the line of sight. They found a notable excess of pairs showing correlated speed offsets compared to pairs showing anticorrelated speed offsets.
“The excess of correlated satellite pairs suggests the presence of recently accreted or falling satellite galaxies,” said Professor Qi Guo, corresponding author of the paper.
This excess was also found in updated cosmological simulations, but the magnitude of this effect was considerably smaller than in observations. The significant discrepancy between observations and simulations implies that massive galaxy groups are younger in the real Universe.
“Since the age of massive galaxy groups could be closely related to the age of the Universe, these findings consequently suggest a younger Universe compared to that derived from the cosmic microwave background (CMB) by the Planck Collaboration,” he said. Dr. Qing Gu. , first author of the article.
These findings present a challenge to the current cosmological model and may provide valuable insights into the Hubble strain problem.
Reference: “A Younger Universe Implicit in Satellite Pair Correlations from SDSS Observations of Massive Galaxy Clusters” by Qing Gu, Qi Guo, Marius Cautun, Shi Shao, Wenxiang Pei, Wenting Wang, Liang Gao and Jie Wang, January 22, 2024, Nature Astronomy.
DOI: 10.1038/s41550-023-02192-6