Web-like structures, rogue planets, and the light from lonely stars

23 May 2024

Searching for dark energy: the Euclid space telescope supplies astonishingly detailed cosmic views

ESA’s Euclid space mission has released five new, stunningly detailed views of the universe. With these images, scientists will be able to explore the evolution of the universe with greater precision and study the mysterious phenomena of dark matter and dark energy. The new images are part of Euclid’s Early Release Observations. They accompany the mission’s first scientific data, which is now available for researchers to work with, and initial science papers, to which numerous LMU scientists have contributed.

This breathtaking image features Messier 78, a vibrant star nursery enveloped in interstellar dust.

© ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, G. Anselmi.

“The Early Release Observations reveal the excellence of the instruments on board the Euclid satellite,” says LMU physicist Jochen Weller, member in the cluster of excellence ORIGINS. “These early showcase projects impressively demonstrate what we can expect from the mission as a whole: first-rate images that will illuminate our understanding of the universe and in particular the puzzle of its accelerated expansion.”

The space telescope observed 17 astronomical objects, from nearby clouds of gas and dust to distant clusters of galaxies, ahead of Euclid’s upcoming main survey. This survey aims to uncover the secrets of the dark cosmos and reveal how and why the universe looks as it does today. “This space telescope intends to tackle the biggest open questions in cosmology,” says Valeria Pettorino, ESA’s Euclid Project Scientist. “And these early observations clearly demonstrate that Euclid is more than up to the task.”

Messier 78, a vibrant star nursery enveloped in interstellar dust.

Euclid peered deep into Messier 78 using its infrared camera, exposing hidden regions of star formation, mapping its complex filaments of gas and dust in unprecedented detail, and uncovering newly formed stars and planets.

© ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, G. Anselmi.

Web-like structures

Euclid will trace the hidden web-like foundations of the cosmos, map billions of galaxies across more than one-third of the sky, explore how our universe formed and evolved over cosmic history, and study the most mysterious of its fundamental components: dark energy and dark matter.

The images obtained by Euclid are at least four times sharper than is possible with ground-based telescopes. They cover large patches of sky at unrivalled depth, looking far into the distant universe using both visible and infrared light.

“The beauty of Euclid is that it covers large regions of the sky in great detail and depth, and can capture a wide range of different objects all in the same image – from faint to bright, from distant to nearby, from the most massive of galaxy clusters to small planets,” says ESA Director of Science, Prof. Carole Mundell. “We get both a very detailed and very wide view all at once.”

More than beautiful snapshots

Far more than beautiful snapshots, however, the images reveal new physical properties of the universe thanks to Euclid’s novel and unique observing capabilities. Euclid produced this new catalogue in just a single day, revealing over 11 million objects in visible light and 5 million more in infrared light. These scientific secrets are detailed further in a number of accompanying papers released by the Euclid collaboration.

NGC 6744, an archetype of the kind of galaxy currently forming most of the stars in the local Universe

Euclid’s large field-of-view covers the entire galaxy, capturing not only spiral structure on larger scales but also exquisite detail on small spatial scales. This includes feather-like lanes of dust emerging as ‘spurs’ from the spiral arms, shown here with incredible clarity.


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“With Euclid, we see diffuse light that is up to 100,000 times fainter than the darkest night sky on Earth,” says Matthias Kluge, who did his doctorate on this subject with images from the Wendelstein Observatory at LMU and now leads one of the studies. From the Euclid images, his team ascertained that this diffuse starlight in the Perseus galaxy cluster comes from galaxies that were completely torn apart by tidal forces in some cases. Other galaxies were more fortunate: “We were able to demonstrate the existence of 1,100 dwarf galaxies that were still intact, including hundreds with much fainter luminosity than ever before detected in the Perseus galaxy cluster,” reports LMU doctoral student Raphael Zöller, who played a major role in the measurement of these galaxies. “This was possible thanks to the dark image background, the high definition of the images, and the wide field of view.”

The early findings showcase Euclid’s ability to search star-forming regions for free-floating ‘rogue’ planets just four times the mass of Jupiter; study the outer regions of star clusters in unprecedented detail; and map different star populations to explore how galaxies have evolved over time. It can even see the light from stars ripped away from their parent galaxies.

Euclid is a space mission of the European Space Agency (ESA). German participants include LMU, the Max Planck Institute for Astronomy (MPIA) in Heidelberg, the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, the University of Bonn (UB), Ruhr University Bochum (RUB) and the German Space Agency at the German Aerospace Center (DLR) in Bonn.

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