Hubble provides new evidence for dark matter around small galaxiesMarch 13th, 2009 - 1:52 pm ICT by ANI
Washington, March 13 (ANI): The NASA/ESA Hubble Space Telescope has uncovered a strong new line of evidence that halos of dark matter are embedded around small galaxies.
Looking into the turbulent center 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.
The Hubble images provide further evidence that the undisturbed galaxies are enshrouded by a cushion of dark matter that protects them from their rough-and-tumble neighborhood.
Dark matter is an invisible form of matter that accounts for most of the Universes mass.
Astronomers have deduced the existence of dark matter by observing its gravitational influence on normal matter, such as stars, gas and dust.
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, said astronomer Christopher Conselice of the University of Nottingham, UK, and leader of the team that made the Hubble observations.
These dwarfs are very old galaxies that have been in the cluster for 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, he added.
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 said.
Although, the fact that spiral galaxies are destroyed in clusters, while the dwarfs are not, suggests that this is indeed the case, he added.
First proposed about 80 years ago by Swiss astronomer Fritz Zwicky, 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.
Observations by Hubbles 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.
Because dark matter cannot be seen, astronomers detected its presence through indirect evidence.
Conselice and his team derived a new technique for uncovering dark matter in these dwarf galaxies by determining the minimum additional mass contribution from dark matter that the dwarfs must have to protect them from being disrupted by the strong, tidal pull of gravity from larger galaxies. (ANI)
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Tags: dark matter content, dwarf galaxies, dwarfs, evidence for dark matter, fritz zwicky, galaxy cluster, gravitational influence, gravitational tug, halos, hubble images, hubble observations, hubble space telescope, milky way galaxy, nasa, perseus, rough and tumble, spiral galaxies, swiss astronomer, university of nottingham, university of nottingham uk