Euclid: dive into 14 million galaxies, amid dark matter and energy
Zoom in the large Euclid field on a spiral galaxy (personal mosaic). © ESA / Euclid / Euclid Consortium / Nasa, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi CC BY-SA 3.0 IGO
Have you ever seen 14 million galaxies in one glance? Probably not, well here's some of it (all of it below):
Part of the 14 million galaxies (around 3 million) photographed by Euclid, view corresponding to one taken from the Southern Hemisphere of the Earth. We see a bluish nebulous veil on the left, the cluster Abell 3381 in the center right, and at the top a black rectangular area that Euclid probably did not image. © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
14 million galaxies, and me, and me, and me…
If you are looking for your place in the Universe, this is the place to look. We will present this sumptuous mosaic from the Euclid consortium and then detail the objective of this mission like no other.
208 gigapixels of galaxies in a single view!
Euclid's mosaic in a single image. © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
To begin with, here is a 360° panorama of the sky, or rather of space all around us, which dates from the Planck mission. The yellow area is the one photographed by Euclid over two weeks of work. It only represents 1% of its final objective. The black band of dust in the center of the panorama is our galaxy, the Milky Way.
360° view of the space created according to the missions Gaia and Planck. The small yellow area corresponds to the entire area presented by Euclid today, i.e. 260 observations over two weeks and which only represent 1% of the total work to be done! © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
Here are the 14 million galaxies! © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
We zoom in three times to obtain the image presented above, where we can see the famous cluster Abell 3381:
3x zoom on the full mosaic. © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
A 12x zoom allows us to obtain this narrower and more dizzying field (high resolution):
12x zoom: we can see the spiral galaxy NGC 2188 and the famous cluster Abell 3381. © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
We zoom in 36 times on the Abell 3381 cluster. The field here contains hundreds of galaxies of all shapes (giant ellipticals, lenticulars and spirals, as well as dwarf galaxies). © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
The 150x zoom plunges us into the middle of galaxies in full gravitational dance, a tango which will lead them to merge in a few million years:
By zooming in 150 times, we observe the merger of two galaxies. © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
And to finish this abysmal dive into the cosmos, a final 600x zoom on a spiral galaxy!
Spiral galaxy 420 million light years away. It now represents only 0.0003% of the 208 gigapixels of the original mosaic! © ESA / Euclid / Euclid Consortium / NASA, CEA Paris-Saclay, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi
Our heads are spinning, but what does Euclid have to teach us?
Euclid is the father of geometry. Reading his famous “elements” (reference work) would have turned Albert Einstein upside down. It was undoubtedly partly inspired by Euclid that Galileo said: “We must measure everything that can be measured and make measurable what is not.” This is the whole objective of the ESA Euclid mission.
This space telescope is a technological gem, because it photographs the Universe in visible light (550-900 nm) and near infrared (900-2000 nm) to capture the most distant and dust-obscured galaxies – which Infrared can pass through without difficulty. In addition, Euclid has a much wider field of observation than its space counterparts, approximately three times larger than Hubble's field of observation.
Euclid takes over from the Planck mission (ESA), which was one of the major missions of the early 21st century, having made it possible to map the Universe from the Cosmic Microwave Background (or fossil radiation) like never before.
Objectives: dark matter and dark energy, the two greatest mysteries…
By obtaining the most precise map ever made of galaxies and their interactions, its primary objective is to better understand dark matter to perhaps finally characterize it (because we will know better what we are looking for), as well as dark energy.
Dark matter is this gravitational component that we detect indirectly everywhere without being able to understand what it is, as if we saw tree branches moving without knowing the wind.
Dark energy acts on a larger scale. It has an anti-gravitational influence: instead of making objects attract each other, it makes them move away. It is she who is held responsible for the acceleration of the expansion of the Universe. If we kept the analogy with the trees and the earth, then it would be the tectonic movements of the plates which would cause the continents to move apart. By photographing galaxy clusters and measuring their speed, we hope to better characterize this powerful dark energy.
Finally, the galactic dive in video:
