Scientists confounded by new findings on universe's mysterious dark matter

James Marshall
September 14, 2020

Dark matter makes up more than a quarter of the universe, scientists have realized, but they haven't yet learned how to see it directly. Importantly, the more dark matter that's around, the greater the observed lensing effect.

Dark matter accounts for approximately 85% of the matter in the Universe. The fact that these models get the big picture so right has been a strong argument in their favor.

However, a new study suggests that the same model misunderstands the details at scale. The models, however, were based on the researcher's best understanding of dark matter.

This effect in space that results from a star or even a galaxy curving space and thus bending the path of light as it passes the object. A handsome example of this is an Einstein ring, where a single object appears multiple times forming a ring-like arrangement. Its presence is only known through its gravitational pull on visible matter in space. In some cases, I even detected lenses with little problems. Solving the mystery of dark matter will require more observations of deep space and some effective number crunching.

The researchers set up a very simple test, at least conceptually, using a gravity lens.

The presence of something missing from our theories of dark matter and its behavior emerged from comparisons of observations of the dark matter concentrations in a sample of massive galaxy clusters and theoretical computer simulations of how dark matter should be distributed in such clusters. Dark matter in clusters is therefore distributed on both large and small scales.

The distribution of dark matter in clusters is mapped by measuring the bending of light - the gravitational lensing effect - that they produce.

According to this model, the universe was built hierarchically. By examining how light behaves in the images they gather, they have a reasonably good idea of exactly how much matter is in the universe. The rest of the matter out there is invisible. Over time, constant gravity brought the galaxies together to form a large star cluster.

Astronomers measured the amount of gravitational lensing caused by this cluster to produce a detailed map of the distribution of dark matter in it. Not only are they closely related to each other by the gravitational pull of dark matter, the individual cluster galaxies themselves are also filled with dark matter.

That distribution of dark matter can be viewed as a prediction of the models.

Meanwhile, in the real universe ... This evidence is based on unprecedentedly detailed observations of several massive galaxy clusters by NASA's Hubble Space Telescope and the European Southern Observatory's Very Large Telescope (VLT) in Chile. The greater the redshift, the farther the object is.

The reference: "An excess of micro-gravitational lenses observed in galaxy clusters" by Massimo Mingetti, Guido Davoli, Pietro Bergamini, Piero Rosati, Priamvada Natarajan, Carlo Giocoli, and Gabriel B. Kamenya, R., Francesco Calura, Claudio Grillo, Amata Mercurio and Eros Vanzella, 11 September 2020, Science.

The software package then used the data to generate mass distributions for each cluster. Galaxies in the three withdrawals are examples of these effects.

The researchers created 25 simulated clusters using the Universe simulator and performed a similar analysis with the clusters. In real space galaxies, much more than the model caused distortion.

"We were trying to understand what we assumed would be the standard model, and see if we were able to find a match between what the model was predicting between the mass function and the distribution", Meneghetti tells Inverse. Dark matter models predict that there should be more dwarf satellite galaxies around the Milky Way and that they should be wider than they are.

This is not the first contradiction of the type we have seen.

Dark matter is one of the most mysterious stuff in the universe. A team of researchers used nearly 200 images of distant galaxies, whose light has been bent and magnified by this huge cluster, combined with the depth of Hubble data to measure the total mass and dark matter content of this cluster more precisely than ever before. Here is what you need to know.

Researchers suggest that there are two explanations for this discrepancy: we do not appreciate all the properties of the dark matter, nor do we find any in the simulations of the evolution of the universe. Since both of those get the big picture of the Universe largely right, however, the issue is going to be a subtle one and consequently hard to identify, should these results get an independent confirmation. One possibility is that the problem appears to be in galactic regions with a lot of matter-dark matter interactions. If there is something more complicated, it could easily throw out the models.

However, for now, it is possible that there may already be teams with additional data capable of performing similar analyzes, so you will have to wait for these tasks to complete. The Hubble image reveals lensing features on large, distorted arcs (produced by dark matter) and the event produced by smaller-scaled dark matter clumps (shown in the thumbnail images).

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