On Thursday (May 23), the European Space Agency (ESA) and its collaborators released a series of five images taken by the revolutionary Euclid space telescope. The Euclid consortium had previously released five images from the space telescope on November 7, 2023.
Euclid has been called Europe’s ‘detective of the dark universe’ because its wide field of view allows it to track billions of galaxies over ten billion years of cosmic history, giving astronomers tools that can reveal more about two mysterious elements of our cosmos: dark energy and dark matter.
Even before he started collecting scientific data to unravel the mysteries of dark energy and dark matter, collectively called the “dark universe,” Euclid demonstrated his potential with these two incredible sets of images.
That’s why Space.com asked several scientists in different fields to explain which of Euclid’s images from the two releases are their favorites so far, and why.
Related: The Euclid ‘dark universe detective’ telescope has revealed new images of the cosmos – and they’re remarkable
But first, dark universe 101
Dark energy is the temporary name given to the force that accelerates the expansion of the universe, pushing galaxies away from each other faster and faster. So looking at galaxies that existed when the 13.8 billion-year-old universe was only about 4 billion years old could reveal how this force has evolved over time, helping to understand its true nature determine.
Dark matter, on the other hand, is a form in the universe that is virtually invisible because it does not interact with light. This means that it cannot be made up of the particles that make up ‘ordinary’ matter. However, because dark matter halos do have a gravitational influence, they have influenced the development of the largest structures in the universe. Euclid’s field of view is wide enough to capture these structures in a single image, meaning it could help solve the question of how dark matter has influenced galactic evolution.
Dark energy accounts for about 67% of the universe’s energy and matter budget, while dark matter accounts for about 27%. That means the ‘dark universe’ collectively accounts for about 95% of the universe’s contents, including stars, planets, the moon, people, cats, and the rest of the mundane ‘stuff’ we understand (maybe not cats , to be honest) account for only 5% of the universe. That makes the ‘dark universe’, to put it lightly, a major problem.
Euclid takes a walk on the dark side
Luz Ángela García Peñaloza is a cosmologist at Universidad ECCI in Columbia who studies the mystery of dark energy and its influence on cosmic evolution. This means that she has followed Euclid’s development with great interest.
“Euclids observes the universe in a completely new way, and it will provide a gigantic census of the galaxies. Personally, I find it fascinating how beautiful these first photos look, as well as all the amazing information they will reveal,” García Peñaloza told Space.com . “I had to take a deep breath when I saw the images because of their beauty and because of their high resolution.”
When García Peñaloza was asked to choose her favorite image from the Euclid releases, she chose one of the galaxy clusters Abell 2390 (below).
“It’s just breathtaking,” she said. “Any image that reveals information about the distribution of galaxies in the large-scale structure of the universe will provide a handful of information about the nature of the ‘dark side’ of the cosmos.”
Italian astrophysicist Andrea Botteon of the Istituto di Radioastronomia: IRA (INAF-IRA) also selected the Abell 2390 image as his favorite from Euclid’s new set.
“As an astrophysicist who works on galaxy clusters, I can tell you that my favorite of the new release is the image of Abell 2390,” Botteon said. “Along with the previously released image of the Perseus Cluster [below]it demonstrates Euclid’s ability to recover the very low surface brightness emission from galaxies and especially the light within the clusters!”
Amateur astronomer Giuseppe Donatiello has discovered eleven galaxies in astronomical survey data, nine of which are named after him, cementing his place in astronomy textbooks. He explained that each expert will choose a different image of Euclid as their favorite based on their field of expertise. He definitely has a top pick himself, and this one is from Euclid’s November 2023 series of images.
“As a fan of local group and dwarf galaxies in the local universe, I was impressed by the detail in NGC 6822,” Donatiello told Space.com. ‘I have seen images of that galaxy taken with the most powerful ground-based instruments, but the detail and depth of Euclid is at a much higher level. Clusters, nebulae and [globular clusters] are easily recognizable in the Euclid image instead of blurry details. I got lost in that field of view for hours!”
Donatiello also selected his favorite image from the latest Euclid releases.
“Of the new ones, NGC 6744 is the most interesting to me because of the fine details in the spiral arms of the galaxy,” Donatiello continued. “I also do work dealing with stellar flows [stars and gas pulled from their galaxies by tidal forces], and the Euclid images contain information about stellar flows that I just can’t get in lower resolution images. I hope the first public data release [DR1] of Euclid is just as useful as data from other in-depth studies.
“If that’s the case, I’ll have fun!”
David Kipping is an assistant professor of astronomy at Columbia University and studies the existence of moons around planets outside the solar system. He also chose an image from the previous release as his favorite Euclid photo to date.
“These are beautiful images that really show off the impressive field of view. The Horsehead Nebula has to be my favorite!” Kipping told Space.com. “Of course, these images are mainly intended for public consumption and not for science, so I am especially looking forward to the first scientific results.”
This new set of images and the previous set are part of Euclid’s Early Release Observations and were collected before February 14, 2023, when the space telescope began its main science operations. Both sets of spectacular images therefore represent only a small part of the observations that the telescope will make during its primary mission over the next six years.
Related stories:
— The ‘dark universe’ Euclid telescope is back on track after finding its guiding stars
– Who is the Euclid space telescope from the ‘dark universe’ named after?
– How will the European Euclid Space Telescope look into the dark universe?
García Peñaloza said that while these new images and the previous set show that Euclid is meeting expectations, the space telescope still has a lot to offer.
“This is just the beginning of what we will be able to see during Euclid’s lifetime,” concluded García Peñaloza. ‘I am convinced that Euclid will shed light on our understanding of many cosmic mysteries. The best is yet to come from Euclid!’