Mapping the Universe: Euclid’s mission to uncover cosmic mysteries

In July, a telescope launched into space with one core aim – to answer some of science's biggest questions about the nature of the Universe.

Set to revolutionise studies across astronomy, researchers from Newcastle University are making their mark by developing new ways to extract the data.

Contents:

1. What are the aims of the mission?
2. What is dark matter and dark energy?
3. What will the mission involve?
4. What's been involved in getting Euclid off the ground?
5. What do our researchers have to say?

On Saturday 1 July 2023, the Euclid telescope began its million-mile journey into space. Due to spend the next six years surveying galaxies as far as 10 billion lightyears away from Earth, the mission aims to shed light on two of the Universe’s big mysteries: dark matter and dark energy.

What are the aims of the mission?

Built by the European Space Agency (ESA), the space telescope is set to “change our understanding of nature” by mapping the dark Universe, according to Dr Cora Uhlemann of Newcastle University. Using the positions of galaxies and images of dark matter, it will create advanced 3D maps of the cosmos like we’ve never seen before.

These maps will contain information about the expansion history of the Universe and the growth of structure within it. By analysing them, astronomers will be able to determine the nature of dark matter and dark energy - providing a legacy database for both astronomers and the public to explore.

What is dark matter and dark energy?

Unlike normal matter which doesn’t reflect or emit light, dark matter binds galaxies together, creating the environment for stars, planets, and life.

Dark energy is the mysterious phenomenon which is pushing galaxies away from each other and is believed to be causing the expansion of the Universe to accelerate.

A simulated high-resolution map of dark matter covering a size of 4 full moons (1 square degree). Euclid will measure a map that is 15,000 times that size, revealing a filamentary cosmic web of structure shaped by gravitational clustering. Made by: Dr Joachim Harnois-Déraps.

What will the mission involve?

Euclid is travelling over one million miles into space away from the Sun, where it will orbit the Sun once a year in step with the Earth. From there, it will scan the sky and send petabytes of data back to ESA’s ground stations.

The data will then be distributed across nine Euclid Science Data Centres, including the UK’s Science Data Centre in Edinburgh. Here, Euclid's data - along with statistics from other ground-based astronomical surveys -will be processed day and night, ready for teams of scientists to work on and evaluate.

The Euclid Consortium team will carry out an accurate analysis of the images and distances of 1.5 billion galaxies, over one-third of the sky. To do this, the teams will measure an effect called gravitational lensing from Euclid’s sample to a precision of 1/100,000, helping to reveal the nature of dark matter.

It doesn’t stop there. Euclid will also measure the spectrum of light from over 35 million galaxies to determine their distance from Earth. It will do this using two state-of-the-art instruments: an optical camera (VIS) and a Near-Infrared (NISP) camera.

The VIS Instrument will take images as sharp as those from the Hubble Space Telescope to measure the gravitational lensing distortions, while the NISP Instrument will take multicolour images and identify the spectrum of light of galaxies – allowing their distance from Earth to be precisely measured and documented.

Impressively, because of its wide field of view and large instruments, Euclid will be able to picture more area of sky in one day than Hubble in its first 25 years.

An illustration of the joint statistics of foreground galaxy counts and the weak lensing of background galaxy shapes by the dark matter in the foreground. Gravitational clustering causes a skewed distribution of matter in the Universe: most regions have densities below average (dashed line), while some regions feature concentrated structures with much higher densities than average. Made by: Dr Lina Castiblanco Tolosa.

What’s been involved in getting Euclid off the ground?

To carry out the ambitious mission, more than 2,000 scientists from Europe - along with the ESA and industrial teams - have come together to design, build and analyse the data from the space telescope.

From co-leading the teams defining the programme and observational strategy, and managing the construction of the VIS Instrument, to leading the gravitational lensing data analysis and production of its high-level data products, as well as coordinating the analysis for Euclid - the UK has played an important role in the entire design and build process.

What’s more – with the help of the STFC Centre for Doctoral Training in Data Intensive Science, known as NUdata - members of Newcastle University’s research groups for Cosmology and Observational Astronomy are involved in developing new methods for extracting Euclid’s data.

The team at Newcastle University, including Dr Cora Uhlemann (Reader in Cosmology), Dr Joachim Harnois-Déraps (STFC Ernest Rutherford Fellow) and Dr Lina Castiblanco Tolosa (STFC-funded Research Associate), will work on establishing new statistics and ways to extract fundamental physics from Euclid’s data for galaxy clustering and weak gravitational lensing.

What do our researchers have to say?

Dr Cora Uhlemann of Newcastle University, who co-leads the Additional Galaxy Clustering Probes work package in Euclid, said:

"This is an exciting time for cosmology and astronomy more broadly. Combining the exquisite Euclid data with theoretical models and numerical simulations will allow us to answer some of the biggest questions we have about the Universe and its future. It’s remarkable what the international collaboration of Euclid’s many scientists and engineers has achieved, and Euclid’s results could change our understanding of nature."

You might also like:

• Updates about the first few months of Euclid’s journey, from the European Space Agency
• Explore the work done by our School of Mathematics, Statistics and Physics
• Press release giving more insight into the STFC Centre for Doctoral Training in Data Intensive Science, NUdata
• The latest research stories and topical pieces on our FROM Blog
• The press release about the Euclid mission

Header image credit: ESA/Euclid/Euclid Consortium/NASA. Background galaxies: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team, CC BY-SA 3.0 IGO