In the vast cosmos, a remarkably dense galaxy draws the attention of astronomers. Located at more than seventeen billion light years from Earth, JWST-ER1, discovered thanks to the James Webb space telescope (JWST) of NASA, reveals clues to the enigmatic nature of dark matter.
What is an Einstein ring?
When the light from a distant source, like a galaxy, passes near a very dense mass such as another galaxy or a cluster of galaxies, the gravity of this mass acts as a lens which deforms the trajectory of light. This phenomenon, predicted by the theory of general relativity of Albert Einstein, is known as
gravitational lens.
In the particular case of JWST-ER1, this gravitational lens has created a remarkable effect called Einstein ring. Such a ring is formed when the light source, the gravitating lens and the observer are very precisely aligned. The light rays are then deflected around the intermediate mass and end up joining the other side, thus forming a circle of light.
A galaxy dense than it seems
By assessing the extent of the deformation of the space-time caused by JWST-ER1G, the researchers then estimated that the galaxy has a mass of approximately
650 billion times that of the sunwhich places it among the galaxies The densest for their size.
By removing the mass from the visible stars of this total estimate, the physicists were then able to quantify the contribution of the dark matter in the composition of the galaxy. According to the calculations, it could approximately fill half of the mass gap observedsuggesting that another mass source may be necessary to fully explain the results of the observed gravitational lens.
The JWST-ER1 galaxy, remarkably dense, and its Einstein ring, captured by the James Webb space telescope last year. Credits: P. Van Dokkum et al., Nature Astronomy, 2023
Several hypotheses, some of which are related to dark matter
The researchers advance several ideas to explain the nature of this additional mass. One possibility is that there is a Dense stars population that what was thought before in the JWST-ER1G galaxy. If this is the case, this could contribute to a part of the missing mass observed.
Another scenario envisaged is that where ordinary material (gas and stars) contracts and condenses in the halo of dark matter of JWST-ER1G. This contraction could increase the density of matter in the galaxy, thus contributing to the observed mass difference. This densification could occur on different scales, from localized regions of stellar formation to larger galactic structures such as spiral arms or active nuclei of galaxies.
Finally, a more daring hypothesis this time concerns the very nature of dark matter. Researchers are considering the possibility that this
interact with herselfthus creating self -contained processes that affect its density and distribution in the galaxy. This interaction could then explain the observed mass gap, as well as other intriguing characteristics of JWST-ER1G.
By combining additional observations with computer simulations and advanced theoretical models, the researchers hope to elucidate the origin of this additional mass and understand in detail the complex dynamics of JWST-ER1G. These in -depth investigations could not only enlighten our understanding of dark matter and the formation of galaxies, but also to open up new perspectives on the fundamental physics of the universe.
The study details are published in The Astrophysical Journal Letters.
