Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

In search of dark energy

16.12.2015

An international consortium of astrophysicists is currently measuring the three-dimensional structure of the Universe by means of an X-ray satellite. Among many exciting prospects, the project will provide new insights into the nature of dark energy. Dark energy is thought to cause the Universe to expand at an ever faster rate. A series of 13 articles appears in the ’Astronomy and Astrophysics’ journal in which the team presents their first results. The X-ray data processing was performed in Bonn.

Our Universe looks like a gigantic sponge: vast spaces (the holes of the sponge) are completely devoid of matter. Filaments made of galaxies and interstellar gas delineate the boundaries of the voids. These form the main structure of the sponge.


The XXL Project monitors two parts of the universe (XXL North and XXL South). The white dots show the galaxy clusters detected so far, the red dots the 100 brightest clusters.

(c) Project XXL - D. Pomarède (SDvision software)

Where filaments cross, the matter density is the largest: thousands of galaxies aggregate in small volumes. These are known as clusters of galaxies. Researchers from all over the world are currently busy measuring this structure.

Indeed, it provides a wealth of information on the origin of the Universe. In particular, scientists hope to shed light on a mysterious constituent of our Universe, the dark energy. This diffuse energy component essentially works like an interstellar baking powder: it drives the cosmos to inflate ever faster.

Dark matter and dark energy

Our ability to see the stars glow in a clear night sky results from a small irregularity. During the big-bang all the cosmic material was gathered into one huge gazeous cloud – almost uniformly, but not exactly: in certain places the cloud was a little bit denser than in others.

Hence, these overdense areas exerted a stronger gravitational pull and attracted the surrounding material to them. With time, more and more matter concentrated around these seeds. In contrast, the space between them became ever emptier. This is how the sponge structure that we now witness has taken shape over the past 13 billion years.

Some 40 years ago, observations revealed that galaxies spin so fast that they should lose the stars inside them due to the centrifugal force. An invisible substance seems to prevent this from happening by its gravitational attraction – the dark matter. About 85 percent of the matter in the Universe is composed of this exotic constituent. The dark matter also accelerated the formation of the sponge structure we see today.

The dark matter makes the Universe so heavy that it should significantly slow down the expansion of the Universe. Yet, this does not happen: according to recent observations, the expansion has actually sped up. The probable cause of this phenomenon is the dark energy. It is tearing appart the Universe in spite of the powerfull gravitational attraction. What exactly dark energy is made of remains unknown.

To help answer this question, an international team of researchers are using a satellite from the European Space Agency (ESA) that is capable of detecting X-rays to map a large area of the sky to an unprecedented depth. The hot gas in clusters of galaxies radiates X-ray emission and can therefore be observed with this satellite. The scientists intend to discover about 500 of these clusters of galaxies and to study them in detail.

Some of them are as far as 10 billion light-years away – 2/3rd of the size of the observable universe. With these clusters, they intend to map out the three dimensional structure of a representative portion of the Universe. By using clusters of galaxies to accurately trace the skeleton of this structure, the team can investigate the forces that gave it shape: both the gravitational pull induced by the distribution of regular and dark matter, but also the mysterious counteracting dark energy.

’We have processed the X-ray data at the University of Bonn’, explains Dr. Florian Pacaud from the Argelander-Institut für Astronomie. ’In the present series of publications, we present a first part of our results, the analysis of the 100 brightest clusters of galaxies’. With this, the scientists could already confirm a recent result that puzzled the cosmologists in the last couple of years: there seem to be significantly less clusters than expected. In addition, the researchers directly observed the process of structure formation in action: they found clear evidence for the existence of superclusters in their observations. Superclusters consist of several clusters of galaxies bound together by their respective gravity. They are expected to collapse into a larger cluster of galaxies in the near future.

More than 100 scientists from all over the globe collaborate in this large project entitled ’XXL’. The project is lead by Dr. Marguerite Pierre from the CEA/Saclay Institute in France. More details can be found on the dedicated website: http://irfu.cea.fr/xxl.

Publication: F. Pacaud et al.: The XXL Survey: II. The bright cluster sample - catalogue and luminosity function; Astronomy and Astrophysics

Contact:

Dr. Florian Pacaud
Argelander-Institut für Astronomie
University of Bonn
Tel. 0228/736788
Email: fpacaud@uni-bonn.de

Weitere Informationen:

http://arxiv.org/abs/1512.04264 Publication

Johannes Seiler | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>