What is the universe made of?

December 02, 2015

Matter known as ordinary, which makes up everything we know, corresponds to only 5% of the Universe. Approximately half of this percentage still eluded detection. Numerical simulations made it possible to predict that the rest of this ordinary matter should be located in the large-scale structures that form the 'cosmic web' at temperatures between 100,000 and 10 million degrees. A team led by a researcher from the University of Geneva (UNIGE), Switzerland, observed this phenomenon directly. The research shows that the majority of the missing ordinary matter is found in the form of a very hot gas associated with intergalactic filaments. The article reporting this discovery is published in the journal Nature.

Galaxies are formed when ordinary matter collapses then cools down. In order to understand the origin of this formation, it was vital to discover in what form and where the ordinary matter that we do not perceive -- known as the 'missing baryons' -- is found. To do this, the astrophysicists from UNIGE and the Ecole polytechnique fédérale de Lausanne (EPFL) took an interest in Abell 2744, a massive cluster of galaxies with a complex distribution of dark and luminous matter at its center. They observed this cluster with the XMM space telescope, which is capable of detecting the signature of very hot gas due to its sensitivity to X-rays.

Hot gas at the core of the filaments

Large-scale galaxy surveys have shown that the distribution of ordinary matter in the Universe is not homogeneous. Instead, under the action of gravity, matter is concentrated into filamentary structures, forming a network of knots and links called the 'cosmic web'. The regions experiencing the highest gravitational force collapse and form the knots of the network, such as Abell 2744. Comparable to neural networks, these knots then connect to one another through filaments, wherein the researchers identified the presence of gas, and consequently, the missing baryons. The astrophysicists pointed XMM in the direction of the areas where they suspected to find the presence of filaments, and therefore, the presence of 10-million degree hot gas structures. For the first time, they were able to measure the temperature and density of these objects, and found that they corresponded to the predictions of the numerical models. For this reason, we now have a grasp of the form taken by the missing ordinary matter.

Will the amount of ordinary matter in the universe soon be known?

This research is a very significant validation of the models of galaxy formation in the Universe. "Now we must verify that the discovery of Abell 2744's missing baryons is applicable to the entire universe. This will consist in studying these filamentary regions in detail, and measuring their temperature distribution and the various atoms that compose them, in order to understand how many heavy elements there are in the universe," says Dominique Eckert, led scientist. In fact, if the researchers manage to measure the atoms in these filaments, they will be able to estimate the number of heavy nuclei formed by stars since the beginning of the universe. In order to deepen this research, the European Space Agency (ESA) is in the process of developing a new space telescope. Switzerland and the researchers from UNIGE are especially involved in this project. The telescope, named Athena, should be operational in the mid-2020s.
-end-


Université de Genève

Related Space Telescope Articles from Brightsurf:

Spitzer space telescope legacy chronicled in Nature Astronomy
A national team of scientists Thursday published in the journal Nature Astronomy two papers that provide an inventory of the major discoveries made possible thanks to Spitzer and offer guidance on where the next generation of explorers should point the James Webb Space Telescope (JWST) when it launches in October 2021.

Unveiling rogue planets with NASA's Roman Space Telescope
New simulations show that NASA's Nancy Grace Roman Space Telescope will be able to reveal myriad rogue planets - freely floating bodies that drift through our galaxy untethered to a star.

Hubble makes the first observation of a total lunar eclipse by a space telescope
Taking advantage of a total lunar eclipse, astronomers using the NASA/ESA Hubble Space Telescope have detected ozone in Earth's atmosphere.

Stunning space butterfly captured by ESO telescope
Resembling a butterfly with its symmetrical structure, beautiful colours, and intricate patterns, this striking bubble of gas -- known as NGC 2899 -- appears to float and flutter across the sky in this new picture from ESO's Very Large Telescope (VLT).

CHEOPS space telescope ready for scientific operation
CHEOPS has reached its next milestone: Following extensive tests in Earth's orbit, some of which the mission team was forced to carry out from home due to the coronavirus crisis, the space telescope has been declared ready for science.

Scientists build a 'Hubble Space Telescope' to study multiple genome sequences
Scientists can now simultaneously compare 1.4 million genetic sequences, helping classify how species are related to each other at far larger scales than previously possible.

James Webb Space Telescope could begin learning about TRAPPIST-1 atmospheres in a year
New research from astronomers at the University of Washington uses the intriguing TRAPPIST-1 planetary system as a kind of laboratory to model not the planets themselves, but how the coming James Webb Space Telescope might detect and study their atmospheres, on the path toward looking for life beyond Earth.

Kepler Space Telescope's first exoplanet candidate confirmed
An international team of astronomers announced the confirmation of the first exoplanet candidate identified by NASA's Kepler Mission.

Space telescope detects water in a number of asteroids
Using the infrared satellite AKARI, a Japanese research team has detected the existence of water in the form of hydrated minerals in a number of asteroids for the first time.

The Hubble Space Telescope discovers the most distant star ever observed
An international team, including researchers from the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL), participated in the discovery of a star at a distance of nine billion lightyears from Earth.

Read More: Space Telescope News and Space Telescope Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.