Emerging: Proof of the existence of dark matter by statistical analysis?

[ack]

Today, scientists at the Institut d'Astrophysique Spatiale (CNRS/Université Paris-Saclay) may have detected, for the first time, this hidden matter through an innovative statistical analysis of 20-year-old data. Their findings are published on November 6, 2020 in Astronomy & Astrophysics.

Galaxies are distributed throughout the universe in the form of a complex network of nodes connected by filaments, which are in turn separated by voids. This is known as the cosmic web. The filaments are thought to contain almost all of the ordinary (so-called baryonic) matter of the universe in the form of a diffuse, hot gas. However, the signal emitted by this diffuse gas is so weak that in reality 40 to 50% of the baryons go undetected.

These are the missing baryons, hidden in the filamentary structure of the cosmic web, that Nabila Aghanim, a researcher at the Institut d'Astrophysique Spatiale (CNRS/Université Paris-Saclay) and Hideki Tanimura, a post-doctoral researcher, together with their colleagues, are attempting to detect. In a new study, funded by the ERC ByoPiC project, they present a statistical analysis that reveals, for the first time, the X-ray emission from the hot baryons in filaments.

This detection is based on the stacked X-ray signal, in the ROSAT2 survey data, from approximately 15,000 large-scale cosmic filaments identified in the SDSS3 galaxy survey. The team made use of the spatial correlation between the position of the filaments and the associated X-ray emission to provide evidence of the presence of hot gas in the cosmic web and for the first time, measure its temperature.


These findings confirm earlier analyses by the same research team, based on indirect detection of hot gas in the cosmic web through its effect on the cosmic microwave background. This paves the way for more detailed studies, using better quality data, to test the evolution of gas in the filamentary structure of the cosmic web.

Has the hidden matter of the universe been discovered?

Astrophysicists consider that around 40% of the ordinary matter that makes up stars, planets and galaxies remains undetected, concealed in the form of a hot gas in the complex cosmic web. Today, scientists at the Institut d'Astrophysique Spatiale (CNRS/Université Paris-Saclay) may have detected...

phys.org

 

[astrotoy]

Very interesting! This is one of two gigantic mysteries that has upended astronomy in the past half century. When Vera Rubin determined that much of the mass of a galaxy (determined by orbital speeds of stars around the center of a galaxy) was not visible (somewhere around 80%), the invisible matter was called "dark matter". If these observations are confirmed, it would mean that the "dark matter" has been essentially hiding in plain sight - not emitting enough energy to be visible.

The other, even bigger mystery, is why the universe is accelerating while it is expanding, and that has been called "dark energy". Nothing yet on the horizon of what it is or how is can be detected.

To give a perspective, after completing my studies in astronomy 40 plus years ago, astronomers were pretty confident that we could see or at least infer everything - 100% of the universe. With the implications of dark matter - the visible universe dropped to about 20%, with 80% dark matter. Then with the discovery of the acceleration of the expansion of the universe about 20 years ago, the implied "dark energy" would have to be 75% of the universe, dark matter 20% and the visible universe that we thought we knew was everything, down to 5%.

Larry

 

[ack]

Very well said, thanks. To be honest, after all the advancements in recent years, I am starting to give some serious thought to the wild suggestions that the Big Bang was the result of the merger of multiple black holes of gargantuan proportions from another universe or universes, the size of which may not be comprehensible by our rather minuscule brains. Color me any which way you want.

 

[steve williams]

Very well said, thanks. To be honest, after all the advancements in recent years, I am starting to give some serious thought to the wild suggestions that the Big Bang was the result of the merger of multiple black holes of gargantuan proportions from another universe or universes, the size of which may not be comprehensible by our rather minuscule brains. Color me any which way you want.

I still like the Big Crunch Theory

 

[BlueFox]

I wonder what we will know in 50 years.

 

[astrotoy]

I still like the Big Crunch Theory

Steve, when I was in grad school, the big question was whether the expansion of the universe was slowing down enough to stop, reverse, and end in a big crunch (and maybe another big bang), or slow down, but not enough to stop. After all it had to be one or the other - since gravity would be slowing it down. So when it was discovered that the universe was actually speeding up in its expansion, that fundamentally contradicted the standard accepted model of the universe. It also resulted in the Nobel Prize being given to the leaders of the two teams which made this discovery - one is Berkeley astronomer Saul Perlmutter. The concept of dark energy is required if Einstein's General Theory of Relativity is correct. Einstein's General Theory has been so well tested and shown to make exactly the correct predictions of experiments, that is is very hard to believe it is incorrect - hence the need for some sort of dark energy.

Larry