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 UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

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: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>