Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hubble Provides New Evidence for Dark Matter Around Small Galaxies

13.03.2009
The Hubble Space Telescope has uncovered a strong new line of evidence that galaxies are embedded in halos of dark matter. Peering into the tumultuous heart of the nearby Perseus galaxy cluster, Hubble's sharp view resolved a large population of small galaxies that have remained intact while larger galaxies around them are being ripped apart by the gravitational tug of other galaxies. The dwarf elliptical galaxies' "invisible shield" is a robust halo of dark matter that keeps them intact despite a several-billion-year-long bumper-car game inside the massive galaxy cluster.

NASA's Hubble Space Telescope has uncovered a strong new line of evidence that galaxies are embedded in halos of dark matter.

Peering into the tumultuous heart of the nearby Perseus galaxy cluster, Hubble discovered a large population of small galaxies that have remained intact while larger galaxies around them are being ripped apart by the gravitational tug of other galaxies.

Dark matter is an invisible form of matter that accounts for most of the universe's mass. Astronomers have deduced the existence of dark matter by observing its gravitational influence on normal matter, consisting of stars, gas, and dust.

The Hubble images provide further evidence that the undisturbed galaxies are enshrouded by a "cushion" of dark matter, which protects them from their rough-and-tumble neighborhood.

"We were surprised to find so many dwarf galaxies in the core of this cluster that were so smooth and round and had no evidence at all of any kind of disturbance," says astronomer Christopher Conselice of the University of Nottingham, U.K., and leader of the Hubble observations. "These dwarfs are very old galaxies that have been in the cluster a long time. So if something was going to disrupt them, it would have happened by now. They must be very, very dark-matter-dominated galaxies."

The dwarf galaxies may have an even higher amount of dark matter than spiral galaxies. "With these results, we cannot say whether the dark-matter content of the dwarfs is higher than in the Milky Way Galaxy," Conselice says. "Although, the fact that spiral galaxies are destroyed in clusters, while the dwarfs are not, suggests that is indeed the case."

First proposed about 80 years ago, dark matter is thought to be the "glue" that holds galaxies together. Astronomers suggest that dark matter provides a vital "scaffolding" for the universe, forming a framework for the formation of galaxies through gravitational attraction. Previous studies with Hubble and NASA's Chandra X-ray Observatory found evidence of dark matter in entire clusters of galaxies such as the Bullet Cluster. The new Hubble observations continue the search for dark matter in individual galaxies.

Observations by Hubble's Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus Cluster, located 250 million light-years away and one of the closest galaxy clusters to Earth. Of those galaxies, 17 are new discoveries.

Because dark matter cannot be seen, astronomers detected its presence through indirect evidence. The most common method is by measuring the velocities of individual stars or groups of stars as they move randomly in the galaxy or as they rotate around the galaxy. The Perseus Cluster is too far away for telescopes to resolve individual stars and measure their motions. So Conselice and his team derived a new technique for uncovering dark matter in these dwarf galaxies by determining the minimum mass the dwarfs must have to protect them from being disrupted by the strong, tidal pull of gravity from larger galaxies.

Studying these small galaxies in detail was possible only because of the sharpness of Hubble's Advanced Camera for Surveys. Conselice and his team first spied the galaxies with the WIYN Telescope at Kitt Peak National Observatory outside Tucson, Ariz. Those observations, Conselice says, only hinted that many of the galaxies were smooth and therefore dark-matter dominated. "Those ground-based observations could not resolve the galaxies, so we needed Hubble imaging to nail it," he says.

The Hubble results appeared in the March 1 issue of the Monthly Notices of the Royal Astronomical Society.

Other team members are Samantha J. Penny of the University of Nottingham; Sven De Rijcke of the University of Ghent in Belgium; and Enrico Held of the University of Padua in Italy.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA) and is managed by NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Md. The Space Telescope Science Institute (STScI) conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.

STScI is an International Year of Astronomy 2009 (IYA 2009) program partner.

Donna Weaver | Newswise Science News
Further information:
http://hubblesite.org/news/2009/11
http://www.spacetelescope.org/news/html/heic0903.html

More articles from Physics and Astronomy:

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

How gut bacteria can make us ill

18.01.2017 | Life Sciences

On track to heal leukaemia

18.01.2017 | Health and Medicine

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>