An international team of scientists led by the Institute of Cosmos Sciences at the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC) has presented REGALADE, an unprecedented catalogue covering the entire sky and bringing together nearly eighty million galaxies. The work, published in the journal
Astronomy & Astrophysics, marks a turning point for astronomy and opens up a new scenario that allows researchers to explore cosmic events with a degree of precision never before achieved.
The study was led by Hugo Tranin, a researcher at ICCUB, and included the participation of ICCUB-IEEC researchers Nadia Blagorodnova, Marco Antonio Gómez Muñoz and Maxime Wavasseur. The study combines expertise in time-domain astrophysics, binary star evolution, large astrophysical catalogues and multi-messenger astronomy, with the aim of developing comprehensive resources that enable the scientific exploitation of the new generation of time-based cartographies with observations from both the ground and space.
A catalogue with precise distances and measurements
When a telescope detects a sudden phenomenon, such as a supernova or the merger of two black holes or neutron stars, astronomers need to know where to look and how far away the event occurred. This requires identifying the galaxy where the event takes place. To date, catalogues were incomplete beyond about 300 million light-years, leaving large gaps in the map of the nearby universe.
REGALADE fills these gaps by combining data from large surveys and cleaning them using data from the Gaia mission to remove stars mistakenly classified as galaxies. The result is a catalogue of high purity and integrity that includes precise distance and size measurements for all galaxies, and stellar masses for most of them.
“REGALADE began as a challenge to improve the user experience: astronomers relied on many popular catalogues, but each one only covered part of the sky or lacked key information,” explains Hugo Tranin, lead author of the study.
“By merging data from 14 widely used catalogues and deep imaging surveys, we now have a single, unified place to look up distances and features of galaxies,” he adds. “This dramatically simplifies the daily work of astronomers and allows our team to obtain distances for more than 75% of the transient phenomena reported worldwide each day.”
The team has also launched an interactive sky viewer that allows the public to explore the REGALADE catalogue and navigate millions of galaxies with just a few clicks.
The scale and depth of REGALADE are extraordinary: it covers the entire sky to more than six billion light-years, and can map nearly 10% of the volume of the observable universe. This comprehensiveness allows astronomers to identify many more host galaxies for all types of cosmic events, from infrared to X-rays, and significantly improve strategies for tracking gravitational waves.
According to Nadia Blagorodnova, co-author of the article, “observatories such as Vera Rubin will detect millions of cosmic events every night.” “REGALADE,” she explains, “ensures that we can identify their host galaxies quickly and accurately, allowing us to rapidly classify rare transient phenomena, such as luminous red novae, which are stellar mergers that our team is actively studying. This will open the door to the discovery of completely new types of celestial phenomena.”