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Examining the Dark Universe, Euclid finds scenes of cosmic light By Katrina Miller
Euclid, a European Space Agency telescope launched into space last summer, finally showed what it is capable of with a series of breathtaking images and the first scientific results published Thursday.
The telescope will help astronomers make sense of two of the universe’s greatest mysteries: dark matter, the invisible glue that holds galaxies together, and dark energy, the force that pushes them apart.
“Before trying to understand what it is, we need to understand how it behaves,” said Jean-Charles Cuillandre, astronomer at CEA Paris-Saclay, referring to dark matter.
The mysterious substance causes light to bend and distort, an effect known as gravitational lensing. In extreme cases, the lens causes galaxies to appear warped and can even produce mirror images of a single source.
Euclid caught this effect while observing Abell 2390, a galaxy cluster located 2.7 billion light-years away. Ninety percent of the mass of this cluster is made up of dark matter.
Gravity causes dark matter to clump together, but dark energy counteracts this effect. Studying the density of dark matter in the cosmos will help astronomers understand how dark energy affects the structure of our universe.
Euclid’s specialty is capturing large portions of the sky in impressive detail. Galaxies that appear near bright stars like Beta Phoenicis may be impossible for some observers on Earth to see, but Euclid’s sharp eyes can resolve them.
The telescope’s sensors make it like a net for light, Dr. Cuillandre said. “Catch everything.”
In a series of articles, the Euclid team also shared discoveries of new dwarf galaxies, star clusters and floating planets. Astronomers say these show how the mission can go beyond its primary objectives.
“We call them legacy science, the things that Euclid can also do,” said Michael Seiffert, a cosmologist working on the mission at NASA’s Jet Propulsion Laboratory.
The telescope photographed these two galaxies brushing past each other 62 million light-years away, resulting in diffuse edges and tails.
Interactions like this are common. “It is very rare to find an isolated galaxy,” Dr Cuillandre said. “That’s what we’re finding.”
Euclid took this photo of the spiral galaxy NGC 6744, 30 million light-years from Earth.
Interstellar gas and dust come together in the rotation of a spiral galaxy, promoting star formation along its arms. Each blue speck in this image is a small, hot, massive star.
A nearby dwarf galaxy has ripped off one of NGC 6744’s arms. Galaxies also have scars, according to Dr. Cuillandre. “They keep track of what happened” over billions of years, he said.
Euclid also focused on Messier 78, a stellar nursery. With its near-infrared vision, the telescope can peer beyond clouds of gas and dust to reveal the bright blue newborn stars hiding within them.
Stars emit protons and neutrons, shaping surrounding dust and other material, not unlike how wind on Earth sculpts our clouds.
Eventually, cavities form around these stars, releasing their light to shine out into the universe.
The latest images come from just one day of observation. “We’re really just getting started,” Dr. Seiffert said.
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