Research conducted by the Atacama Cosmology Telescope (ACT) collaboration has produced unprecedented images of the universe's earliest moments, captured as cosmic microwave background (CMB) radiation. These images, visible only 380,000 years after the Big Bang, represent a significant advancement in our understanding of cosmic history.
The international team includes astrophysicist Neelima Sehgal and her group from Stony Brook University's Department of Physics and Astronomy. They have played a crucial role in analyzing the CMB, often referred to as the afterglow light from the Big Bang.
Suzanne Staggs, director of ACT and Henry deWolf Smyth Professor of Physics at Princeton University, stated: "We are seeing the first steps towards making the earliest stars and galaxies." She emphasized that this research allows for high-resolution observation of light polarization—a distinguishing feature compared to previous telescopes like Planck.
The new images add higher definition to those observed a decade ago by Planck. The findings will be presented at the American Physical Society Annual Meeting on March 19. The research confirms a simple model of the universe while ruling out most competing theories.
Sehgal remarked on their achievement: “With these images, we have achieved a sensitivity over half the sky that surpasses previous ‘baby pictures’ of the universe.” She highlighted that their data does not show any evidence against the Standard Model of Cosmology.
Jo Dunkley from Princeton University explained: “By looking back to that time, when things were much simpler, we can piece together the story of how our universe evolved.” The ACT’s measurements refine estimates for both the age and expansion rate of the universe.
Recent cosmological debates have focused on differing measurements of the Hubble constant—the rate at which space is expanding. The ACT team confirmed a lower value with increased precision using their new data.
The Stony Brook team has been involved in CMB analysis for over a decade under Sehgal's leadership. ACT completed its observations in 2022; attention now shifts to the Simons Observatory in Chile. This facility has recently achieved first light and involves Stony Brook as an institutional partner.
The ACT data are publicly available on NASA’s LAMBDA archive. Pre-peer review articles related to this release can be found on both the ACT website and arXiv.org.
Funding for Sehgal's research came from various sources including NSF awards and support from institutions like Princeton University and University of Pennsylvania. The project involves 160 collaborators across 65 institutions globally.