Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Canadian team maps "dark matter" halos around galaxies

24.07.2003


Two University of Toronto astronomers and a U.S. colleague have made the first-ever measurements of the size and shape of massive dark matter halos that surround galaxies

‘Our findings give us the clearest picture yet of a very mysterious part of our universe,’ says principal investigator Henk Hoekstra, a post-doctoral fellow at University of Toronto’s Canadian Institute for Theoretical Astrophysics. ‘Using relatively simple physics, we can get our first direct glimpse of the size and shape of these halos which are more than fifty times more massive than the light-producing part of galaxies that we can see.’

Hoekstra and his team present their findings on July 25 at the 25th General Assembly of the International Astronomical Union in Sydney, Australia.



Their research indicates that dark matter halos extend more than five times further than the visible stars in a galaxy, says Hoekstra. In the case of our Milky Way galaxy, he says, the halo extends to more than 500,000 light-years away and weighs approximately 880 billion times more than the sun. The findings also provide strong support for the popular ‘cold dark matter’ model of the universe.

Dark matter emits no light and, therefore, cannot be seen directly, Hoekstra explains. The only evidence for its existence comes from its gravitational pull on stars, gas and light rays. Dark matter is believed to account for approximately 25 per cent of the total mass in the universe, with the rest of the universe composed of normal matter (five per cent) and dark energy (70 per cent).

To date, most information about dark matter has come from measurements of the motion of gas and stars in the inner regions of galaxies. Other important data have come from computer simulations of the formation of the universe’s structure. However, scientists can explain their findings about dark matter only if it is true that galaxies are surrounded by massive, three-dimensional halos.

The majority of astronomers believe in the so-called cold dark matter theory of the universe, which suggests these halos are slightly flattened. Hoekstra’s findings corroborate this. Using the relatively new technique of weak gravitational lensing which allows astronomers to study the size and shape of dark matter, the team measured the shapes of more than 1.5 million distant galaxies using the Canada-France-Hawaii Telescope in Hawaii. ‘The small changes in the shapes of the galaxies offered a strong indication to us that the halos are flattened, like a rubber ball compressed to half its size,’ Hoekstra says.

Their findings can also be applied to a larger scientific debate about the nature of the universe. Some scientists have developed theories about the universe using the assumption that dark matter does not exist and, as a result, they have proposed changes to the law of gravity. However, Hoekstra is confident that his team’s findings will refute these theories.

The research was conducted with Professor Howard Yee of University of Toronto’s Department of Astronomy and Astrophysics and Michael Gladders, a former University of Toronto graduate student now at the Observatories of the Carnegie Institution of Washington in Pasadena, Calif. It was funded by the Natural Sciences and Engineering Research Council of Canada and the University of Toronto.

Contacts:

Henk Hoekstra
Canadian Institute for Theoretical Astrophysics
phone: +1-416-978-8494
email: hoekstra@cita.utoronto.ca

Dr Hoekstra can be contacted through the Media Room
at the IAU General Assembly in Sydney, Australia,
in July 13-26, 2003:
Tel: +61-2-9282 5418, 5419, 5420
Fax: +61-2-9282 5421
Email: iaumedia@netscape.net


Howard K.C. Yee
Department of Astronomy and Astrophysics
University of Toronto
phone: +1-416-978-1771
email: hyee@astro.utoronto.ca

Michael D. Gladders
Observatories of the Carnegie Institution of Washington
phone: +1-626-304-0252
email: gladders@ociw.edu

Nicolle Wahl
University of Toronto Public Affairs
phone: +1-416-978-6974
email: nicolle.wahl@utoronto.ca

Helen Sim | alfa
Further information:
http://www.aao.gov.au

More articles from Physics and Astronomy:

nachricht Discovery of an Extragalactic Hot Molecular Core
29.09.2016 | National Astronomical Observatory of Japan

nachricht Swiss space research reaches for the sky
29.09.2016 | Schweizerischer Nationalfonds SNF

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: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

 
Latest News

New Multiferroic Materials from Building Blocks

29.09.2016 | Materials Sciences

Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”

29.09.2016 | Materials Sciences

X-shape Bio-inspired Structures

29.09.2016 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>