First Images of Dark Matter
An international team of astronomers from Japan, Britain and Taiwan just got, for first time, images that reflect the distribution of dark matter around 20 large clusters of galaxies. The finding confirms the theoretical predictions had been made so far. Dark matter is distributed around galaxies as halos of irregular shapes and often elongated. The research opens new avenues toward understanding the true nature of this enigmatic class of matter not composed of atoms. The results will be published in the monthly magazine of the Royal Astronomical Society.
What is dark matter? The answer to this question is still unknown and is one of the central problems of physics and modern astronomy. And it is that dark matter really does honor to its name in a number of different ways. It is undetectable in both the visible light range and the rest of the wavelengths that are able to solve the best telescopes. Neither in the infrared, or X-rays or ultraviolet dark matter has yet revealed his true nature.
That is precisely why, because it is invisible, its existence must be inferred from gravitational effects it causes in other objects that we can see, such as stars, galaxies and galaxy clusters. These kinds of “circumstantial evidence” have established that dark matter is relatively abundant in our universe. In reality much more abundant than the “normal” and that we can see.
If all the astronomers get to see through their telescopes altogether, that is, all the planets, stars and galaxies that exist, there are no more than a measly 4% of the total mass of the universe. Dark matter, by itself, accounts for another 23% of the total mass. The remaining 74% of the universe we live in is composed of an even more mysterious force that scientists have called dark energy.
But back to the dark matter is, as we have seen, up to five times more abundant than ordinary matter. This means that its contribution, for example, the formation and stability of galaxies must be absolutely necessary for the universe is as it is. Without dark matter, for example, galaxies would not have enough strength to “hold” their stars and manetnerse as stable structures.
In their attempts to unravel the mysteries of dark matter, and given the current inability to observe directly, astronomers try new approaches to the problem. Among them, getting to find out how dark matter is distributed around galaxies and check later if this distribution is consistent with theoretical models. And that is precisely what has made an international team of astronomers under the baton of Masamune Oguri, National Astronomical Observatory of Japan, and Masahiro Takada, University of Tokyo.
Using gravitational lensing, scientists have achieved their objective and have been able to show the first images that see dark matter. The general theory of relativity, Einstein predicted that light from a distant object be bent (due to gravity) as it passed very massive objects, such as a galaxy cluster of concentration of dark matter. This deflection of light is what is known as gravitational lensing and has been the case, measuring the distortion of light from many distant galaxies to Earth, as astronomers have been able to infer the presence, quantity and distribution of dark matter the regions chosen for study.
Using the telescope Subaru, twenty astronomers observed massive clusters of galaxies. This kind of clusters are ideal for this kind of research, since there contain thousands of individual galaxies and a large amount of invisible dark matter whose distribution is intended to measure. Delete observations with the Subaru-Cam galactic super clusters are very distant from us 3,000 million light years.
Analyzing the effect of gravitational lensing in these images, researchers found that overall, the distribution of dark matter around these twenty large clusters of galaxies do not have a spherical shape, but flat and elongated. As predicted by theoretical models.