The Euclid mission: its discovery could revolutionize our current understanding of the cosmos

Euclid 2

Ready for its journey, the Euclid Telescope will investigate the dark matter and energy of the universe

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The Euclid space telescope of the European Space Agency (ESA) will study the “dark universe”. THAT, CC BY-SA
Oscar del Barco Novillo, Zaragoza's University

The European Space Agency (ESA) has launched a Falcon 9 rocket from Cape Canaveral (Florida) carrying the Euclid space telescope. The mission of this new observatory will be to study the most elusive of the universe: dark matter and dark energy.

A month after launch, Euclid will orbit the second Sun-Earth Lagrange point (L2), one and a half million kilometers from our planet. It is a privileged location where the gravitational attractions of the Sun and the Earth “balance.” Once there, your sunshade will block light from the Sun, Earth and Moon, to ensure a high level of stability for your instruments.

Meanwhile, Euclid will begin to point towards the deep sky in an attempt to reveal some of the mysteries that the universe still entails. He will accompany in this position the James Webb Space Telescope, like perfect fellow traveler in this exciting new space age.

Dark matter and dark energy

It is no less curious that everything we have discovered in the universe (from our Solar System to the most distant galaxies) is made up of ordinary matter: elementary particles such as protons, electrons and quarks that come together to form atoms. However, this matter observable It constitutes exclusively the 5 % of the cosmos.

We must ask ourselves, then, the following question: what does the remaining 95 % of dark universe that still remains invisible to us? And even more, what is the evidence of that 95 % of unknown matter or energy in the cosmos?

Starting with the last question, scientists realized several significant facts. On the one hand, stars orbiting their galactic centers move faster than expected (that is, when only the ordinary matter “that we can see” is taken into account). On the other hand, this “observable” matter alone cannot provide enough gravity to maintain galaxy clusters.

This is when a kind of invisible matter comes into play that neither emits nor reflects light and would form the 25 % of the universe: dark matter.

How could dark matter be detected?

A method widely used by astronomers (and that could be used to detect dark matter) is based on the relativistic effect called gravitational lens. When a concentration of matter is placed in our line of sight it can act like a magnifying glass, distorting the light of the galaxies behind it.

In strong gravitational lenses (due to the presence of very massive objects such as galactic clusters or black holes), galactic deformations are very evident. The following animation describes this effect when a black hole moves in front of a galactic background.

When the distortions of the background sources are of lower magnitude we speak of a weak gravitational magnifying glass. In this case, deformations can only be detected by analyzing a large number of sources statistically.

In this sense, the Euclid space telescope will measure the distorted shape of billions of galaxies and create the most detailed and precise 3D map: scientists will be able to deduce how dark matter is distributed in the cosmos.

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Strong (left) and weak (right) gravitational magnifying effect due to the presence of dark matter between the emitting sources and the Earth. The center image shows a large number of undistorted emission sources. Credits: ESA. THAT, CC BY

And where is the 70 % of that one then? dark universe?

It is believed that this 70 % is formed by the so-called dark energy, a kind of “invisible force” not detected to date and that would explain why the expansion of the universe during the last five billion years has accelerated faster than expected. expected.

Euclid will map the last 11.7 billion years of cosmic history, right around the time when most stars were forming. This will allow us to study with extraordinary precision how the acceleration of the universe has changed in that period.

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Illustration of the expansion of the universe highlighting the increase in acceleration over the last 11.7 billion years. Credits: ESA.

The instruments aboard the Euclid

Like the Hubble or James Webb space telescopes, Euclid belongs to the type of reflecting telescopes. This means it uses mirrors to focus light and produce images. Its primary mirror measures 1.2 meters in diameter (half that of Hubble and about 5 times smaller than Webb) and its weight in orbit will be about 2 tons.

With these features, Euclid will achieve cover a third of the sky and measure the shape, position and distance of galaxies 10 billion light years away from us. In addition, it will create a detailed three-dimensional map of the cosmos.

To do this, Euclid has on board the VIS and NISP instruments that will analyze, respectively, the visible and infrared light of the early universe:

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VIS (visible light) and NISP (near infrared) instruments aboard the Euclid Space Telescope. Cretidos: THAT.
  1. The VIS camera It will record visible light from 550 nanometers (yellowish-green color) to the most extreme red. It is made up of a mosaic of 36 CCD sensors with a resolution capacity of 16 megapixels each. You will obtain very sharp images of galaxies, allowing you to measure their shape accurately.

  2. The NASP instrument It operates in the near infrared (like the James Webb) and has 16 detectors of 4 megapixels each. The NASP will measure the brightness and intensity of the light emitted by distant galaxies and will allow us to know their distances (through the effect known as red shift). In addition, it will provide the largest field of view in the infrared range from space (hundreds of times larger than the Webb).

What Euclid will be able to reveal about the universe

This new space observatory will be able to answer questions about the nature of dark matter and energy, the change in the acceleration of the universe, or even whether Einstein's general theory of relativity is valid at larger scales of the cosmos.

Once ready, Euclid will embark on a five-year study with a team of 2,000 scientists from around the world collecting data. It will not be a trivial task, since the analysis of this enormous amount of data could take another five years. That is, we will have to wait almost a decade to obtain results.

Meanwhile, the Euclid space telescope (in honor of the Greek mathematician Euclid, father of geometry) will try to unravel that fascinating dark universe, still invisible to us.The Conversation

Oscar del Barco Novillo, Assistant Professor Doctor. Department of Applied Physics, Zaragoza's University

This article was originally published in The Conversation. read the original.