New catalog of cosmic distances could unlock mysteries of universe formation

A new catalogue providing information on millions of distant galaxies, determining their distances with unprecedented precision over a field of view and depth never before explored, was published today.

The catalogue is the result of the Physics of the Accelerating Universe (PAUS) survey, an international collaboration led by the Department for Science, Innovation and Universities (MICIU) Institute for Space Sciences (ICE-CSIC) involving 14 institutions in six countries, including the University of Portsmouth.

Collected over 200 nights between 2015 and 2019 using the PAUCam camera on the William Herschel telescope on La Palma, this catalogue is now available on the PAUS website and the CosmoHub web portal.

Covering a vast area of ​​50 square degrees, or about 250 full moons, the catalog includes data on 1.8 million astronomical objects. This information will allow astronomers to create more precise maps to understand how structures in the universe form and to study dark matter and dark energy.

Enrique Gaztañaga, PAU Survey Director and Professor at the University of Portsmouth’s Institute of Cosmology and Gravitation, said: “The PAU survey offers an innovative approach to creating cosmic maps, made possible by the design and development of a new instrument and a dedicated survey to collect and analyse data in a way never before possible. It has been a privilege to collaborate with such a talented and trusted group.”

The accelerated expansion of the universe is attributed to dark energy, which makes up about 70% of the universe, but its nature remains a mystery. The PAU study offers new insights into this enigma, providing a precise and comprehensive characterization of millions of galaxies out to distances of more than 10 billion light-years.

This catalog is a valuable resource for the astronomical community, aiding in scientific analysis and calibration of other cosmological studies.

The PAUCam camera was specially designed to precisely measure the distances of galaxies, allowing the study of the expansion of the universe under the influence of dark matter and dark energy.

The project builds on existing deep images from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), conducted with the Canada-France-Hawaii Telescope in Hawaii, and the Kilo-Degree Survey (KiDS) conducted with the European Southern Observatory’s VLT telescope in Chile. By combining these datasets, PAUS has obtained extremely precise distance and time information for deep space objects.

This catalog represents a significant advance in cosmic research, with its vast data providing photometric redshift measurements that determine the distances of galaxies as they appeared billions of years ago.

To make these measurements, the PAU camera uses 40 filters of different colors, representing narrow bands of the optical spectrum. This technique involves photographing the same field multiple times through different color filters. As objects move away from us, the light they emit undergoes a redshift, shifting toward the red end of the spectrum. In astronomy, the redshift is crucial for calculating an object’s distance from Earth.

David Navarro-Gironés, a PhD student at ICE-CSIC and first author of the paper, said: “The accuracy of measuring galaxy distances depends on the number of filters you use, because each filter provides different information about the galaxy.

“The great advantage of PAUS is that it combines information from 40 different filters, which allows extremely precise distance measurements. This level of precision is crucial for studying the structure of the universe, which in turn requires data from a large number of galaxies.”

The publication is detailed in two articles published in the Monthly Notices of the Royal Astronomical Society:one measuring distances and another on calibrating PAUS data.

In the coming months, the team will also present an ongoing study of galaxy clustering and intrinsic galaxy shape alignments, contributing to a deeper understanding of how our universe formed and evolved.