New cosmic distance catalogue may shed light on mysteries of the universe’s formation

A new catalog was published today that provides information on millions of distant galaxies, determining their distances with unprecedented precision, across fields and depths never before explored.

The catalogue is the product of the Accelerated Astrophysics Survey (PAUS), an international collaboration project led by the Institute for Space Sciences (ICE-CSIC) under the Ministry of Science, Technology, Innovation and Universities (MICIU), involving 14 institutions from six countries, including the University of Portsmouth.

The catalog was collected over 200 nights between 2015 and 2019 using the PAUCam camera on the William Herschel Telescope on the island of La Palma, and is now publicly available on the PAUS website and the CosmoHub web portal.

Covering a vast 50 square degree area of ​​the sky (equivalent to about 250 full moons), the catalog contains data on 1.8 million celestial objects, enabling astronomers to create more accurate maps, understand the formation of structure in the universe, and study dark matter and dark energy.

“The PAU Survey provides a groundbreaking approach to mapping the universe, made possible by the design and development of new instruments and dedicated research to collect and analyse data in ways never before seen. It has been a pleasure to work with such a talented and trusted group,” said Enrique Gastañaga, PAU Survey director and professor at the University of Portsmouth’s Institute of Cosmology and Gravitation.

The accelerating expansion of the universe is thought to be due to dark energy, which makes up about 70% of the universe, but its nature remains mysterious. The PAU Survey provides new insights into this mystery, revealing precise and comprehensive properties of millions of galaxies located more than 10 billion light-years away.

The catalog is a valuable resource for the astronomy community and will aid in the scientific analysis and calibration of other cosmological surveys.

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

The project is based on existing deep space images from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), conducted at the Canada-France-Hawaii Telescope in Hawaii, and the Kilo Degree Survey (KiDS), conducted at the European Southern Observatory’s VLT Survey Telescope in Chile. Combining these datasets, PAUS has achieved highly accurate distance and time information on deep space objects.

The catalog represents a major advancement in cosmic research, with its vast data providing photometric redshift measurements that determine the distances to galaxies that emerged billions of years ago.

To make these measurements, the PAU camera employs 40 filters of different colors, representing narrow bands of the optical spectrum. The technique involves photographing the same field multiple times through filters of different colors. As an object moves away from us, the light it emits is redshifted, shifting to the red end of the spectrum. In astronomy, redshift is important for calculating an object’s distance from Earth.

“The precision with which we measure the distances of galaxies depends on the number of filters we use, because each filter provides different information about the galaxy,” said David Navarro-Gironés, a doctoral student at ICE-CSIC and first author on the paper.

“A big advantage of PAUS is that it combines information from 40 different filters, allowing for extremely precise distance measurements. This level of precision is crucial for studies of the structure of the Universe, which require data from a large number of galaxies.”

The announcement is detailed in two articles published in the Monthly Notices of the Royal Astronomical Society: one on the distance measurements, and one on the calibration of the PAUS data.

In the coming months, the team will also publish their ongoing studies on galaxy clustering and unique galactic geometric arrangements, contributing to a deeper understanding of how the universe formed and evolved.