In a groundbreaking study, a team of researchers led by Yulin Gong from the University of Arizona and including members from institutions like the University of Pennsylvania, Ohio University, and the University of Manchester, has achieved a significant milestone in astrophysics. This research, published in the journal Physical Review Letters, focuses on the detection of the pairwise kinematic Sunyaev-Zel’dovich (kSZ) effect, which has practical implications for understanding the large-scale structure of the universe and potentially for the energy sector.
The study presents a 9.3-sigma detection of the pairwise kSZ effect by combining data from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) catalog and cosmic microwave background (CMB) temperature maps from the Atacama Cosmology Telescope (ACT) DR6 and Planck. The team utilized three ACT CMB temperature maps, including a co-added 150 GHz map, total frequency maps, and a component-separated Internal Linear Combination (ILC) map. These maps cover an extensive 19,000 square degrees of the sky, observed between 2017 and 2022. The use of multiple maps serves as a consistency check to ensure that the results are not contaminated by foreground noise that may vary with observation frequency.
The researchers compared the pairwise kSZ curve with the linear-theory prediction of the pairwise velocity under the best-fit Planck cosmology. This comparison allowed them to estimate the best-fit mass-averaged optical depth, which is a measure of the amount of matter along the line of sight. The estimated optical depth was then compared with predictions from simulations, providing a reference point for future studies. One such future study will involve comparing these results with thermal SZ-derived optical depth measurements for the same DESI cluster samples, which will be presented in a companion paper.
Furthermore, the team employed a machine-learning approach trained on simulations to estimate the optical depth for 456,803 DESI Luminous Red Galaxies (LRG)-identified clusters within the simulated mass range (greater than about 1e13 solar masses). These estimates, combined with the measured kSZ signal, enabled the researchers to infer the individual cluster peculiar velocities. This information is crucial for constraining the behavior of gravity and the dark sector over a range of cosmic scales and epochs.
For the energy sector, understanding the large-scale structure of the universe and the distribution of matter can have practical applications. For instance, this research can contribute to the development of more accurate models for dark matter and dark energy, which are significant components of the universe’s energy budget. These models can, in turn, inform the design and deployment of energy technologies that rely on a deep understanding of fundamental physics, such as advanced nuclear energy systems or space-based solar power.
In summary, this study represents a significant advancement in the detection of the pairwise kSZ effect, providing valuable insights into the large-scale structure of the universe. The practical applications of this research for the energy sector lie in its potential to enhance our understanding of dark matter and dark energy, which can inform the development of innovative energy technologies.
This article is based on research available at arXiv.