Astronomer Haojing Yan of the University of Missouri will lead an international team of 130 scientists representing 62 scientific organizations, including NASA, the California Institute of Technology, Princeton and Harvard universities. Their project, the Roman eXtreme Deep Field (RXDF), has been awarded 386 hours of observing time on NASA's newest flagship space telescope, "Nancy Grace Roman". This is reported in a publication on the arXiv preprint server, meaning the paper has not yet undergone full peer review.
The main goal is to obtain one of the deepest and at the same time widest images of the early Universe. The scientists hope to move closer to answering a fundamental question: how the cosmos went from its first moments to the vast assemblage of stars, galaxies and planets we see today.
Looking far away in astronomy means looking into the past. Light travels through space at a finite speed, so objects billions of light-years away are seen as they were billions of years ago. Yan gives a simple example: we see the Sun as it was about eight minutes ago, the time its light takes to reach Earth. The farther away an object is, the earlier a stage of its history the telescope records.
The James Webb telescope has already shown galaxies that, by all appearances, formed far earlier than scientists expected. However, it is not yet clear whether these objects are rare anomalies or part of the general picture. This is exactly where a wide survey is needed: "Roman" will carry a 300-megapixel infrared camera capable of capturing in a single image an area of sky for which "Webb" or "Hubble" would require hundreds of separate observations.
The team plans to study how quickly the first galaxies formed stars and merged into larger structures, to search for distant supernova explosions - exploding stars, that is, stars that end their lives in a powerful explosion - and to work out how giant black holes managed to grow so quickly in the infancy of the Universe. Of particular interest are the mysterious "little red dots" first noticed by "Webb": their nature has still not been established, and "Roman's" wide field of view will help find more such objects for statistically reliable analysis.
However, according to Yan, the loudest discoveries often turn out to be unplanned. "Historically, the most revolutionary results of such deep surveys over the past 30 years have been discoveries that were not in the original plans," he noted. The scientists emphasize that this concerns future observations, not data already obtained, and that it is impossible to predict what exactly the telescope will find.