Dark matter is a hypothetical form of matter that would make up 85% of the universe. It has never been observed directly – in fact, scientists need this dark matter to match observations of many galaxies with the state of our knowledge.
Indeed, when we look at certain spiral galaxies for example, such as the Milky Way, we quickly realize that the rotation speed of stars far from the center is much too fast. This speed actually depends on the total mass of the star cluster – the more massive the set, the faster the peripheral stars are supposed to orbit.
JWST makes it possible to study dark matter like never before
However, by even very generously estimating the mass of such galaxies, we quickly realize that a lot, really a lot of mass is missing to explain such characteristics. That’s why scientists came up with the concept of dark matter. And if it is called dark matter, it is precisely because it has never been detected directly – and even less observed at all.
In fact, everything indicates that this matter, if it exists, interacts very little with visible matter. Dark matter does not emit, absorb or reflect electromagnetic radiation. Which is a real headache to try to detect it because detecting particles normally amounts to studying their charge and mass.
However, because of its weak gravitational interaction, dark matter clusters end up affecting matter altogether, but only on a very large scale. This is why the phenomenon of gravitational lenses and intergalactic light are the subject of intense research at the moment.
Thanks to its unequaled definition, and its observation in the infrared band, JWST immediately enables a new step in the observation of intergalactic light. This allows us to finally “see” the arrangement of clusters of dark matter. Intergalactic light is a halo with very low luminosity which seems to form sorts of filaments between certain large clusters of galaxies.
This light is actually caused by stars being torn from their galaxies by what scientists believe is the gravitational effect of immense amounts of dark matter. Astronomers were already trying to observe this light with Hubble. But as you will see in the video at the end of the article, we have never seen the halo so distinctly.
You can even see its extent and its limits – the galactic cluster on the far right, for example, is not surrounded by this light, which suggests that it is not shrouded in dark matter (or that there is some). has comparatively very little).
