The Dark Matter Halo of the Largest Galaxy Cluster in Stunning Images
The images showcase the dark matter halo of the largest galaxy cluster formed in the simulation at different magnifications. The breathtaking visuals reveal countless stars and galaxies sparkling in the universe, raising the question of how much matter truly exists. While the question appears simple, the answer has proven to be a head-scratcher.
This conundrum stems from the fact that current cosmological observations cannot agree on how matter is distributed in the present-day universe. To help shed light on this, a new computer simulation called FLAMINGO (Full-hydro Large-scale structure simulations with All-sky Mapping for the Interpretation of Next Generation Observations) has been developed. This simulation traces the evolution of all elements in the universe, including ordinary matter, dark matter, and dark energy, according to the laws of physics. The visuals generated by FLAMINGO showcase galaxies and clusters of galaxies forming in the universe, fueled by the cosmic web.
Unlike previous simulations that only considered dark matter, FLAMINGO incorporates ordinary matter as well. Ordinary matter, also known as baryonic matter, contributes to gravity along with dark matter. This realization has led researchers to understand that the contribution of ordinary matter cannot be ignored.
Astronomers view computer simulations like FLAMINGO as not just visually stunning, but also essential for resolving a major discrepancy in cosmology known as the “S8 tension.” This tension revolves around the distribution of matter in the universe and can be characterized by the S8 parameter. Astronomers use this parameter to measure the clumpiness or clustering of matter in the universe. However, S8 values obtained from cosmic microwave background (CMB) experiments are higher compared to values obtained from weak gravitational lensing surveys. This discrepancy has left cosmologists perplexed.
The team behind the FLAMINGO project aimed to address this tension by simulating the effects of both dark matter and ordinary matter. While the simulation considered extreme galactic winds driven by supernova explosions and supermassive black holes, it could not explain the weak clumping of matter observed in the present-day universe. This outcome suggests potential shortcomings in the standard model of cosmology or even the standard model of physics. The S8 tension may be indicating the need for revised models.
Researchers are excited by the possibilities the S8 tension presents. It could hint at exotic self-interactions of dark matter or even a breakdown of the theory of gravity on larger scales. Furthermore, FLAMINGO simulations are helping to rule out more mundane explanations for the tension, such as observational uncertainties or issues with the CMB. The team speculates that the effects of normal matter might be stronger than currently simulated, but the simulations align well with observed properties of galaxies and clusters.
Ultimately, the answer to the S8 tension may lie in understanding what caused the change in the behavior of the universe throughout cosmic history. Resolving this tension has important implications for fundamental physics and cosmology. The team’s research is published in three papers in the Monthly Notices of the Royal Astronomical Society.
