Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny galaxies once roared in the universe, say scientists

26.05.2003


Astronomers led by the University of Colorado and Carnegie Observatories have shown that a miniature galaxy less than one-hundredth the size of the Milky Way is ejecting large quantities of gas and energy into huge regions of intergalactic space.



“This discovery suggests tiny galaxies that appear very faint and dormant today were once much brighter and more active,” said CU-Boulder graduate student Brian Keeney. “It also indicates similar galaxy systems may have been primarily responsible for the chemical evolution of the universe in the very early stages of galaxy evolution,” said Keeney, who presented the results of the research at the American Astronomical Society Meeting held in Nashville, Tenn., May 25 through May 29.

CU-Boulder teamed up with the Carnegie Institution in Washington, D.C., and East Tennessee State University using the Hubble Space Telescope and ground-based telescopes to make a series of observations. Ray Weymann of the Carnegie Institution led a team that used the electromagnetic spectrum from the brightest quasar in the sky, 3C273, to discover a dense cloud of gas in the far reaches of intergalactic space.


Subsequent observations of the cloud showed it contained elements formed in stars and ejected into space by supernova explosions, he said. There was no known source nearby that could have contributed the ancient elements to this gas.

After several years of searching for the source of this intergalactic “pollution”, a team led by CU-Boulder Professor John Stocke and Weymann discovered a tiny “dwarf galaxy” so small that it had been previously overlooked.

Better images and a detailed spectral analysis obtained by Stocke and Keeney at the Apache Point 3.5-meter Telescope in New Mexico showed strong evidence that this tiny galaxy was responsible for forming the gas cloud.

Some of the strongest evidence is the abundance of elements in the gas cloud and of the stars in the galaxy match, Keeney said.

In addition, an unusual “overabundance” of the element silicon in the gas cloud suggests that thousands of supernovas -- the type created when massive stars die --were the source of the gas cloud. A spectral analysis of the dwarf galaxy by Stocke and Keeney showed the dwarf galaxy probably experienced a massive “burst” of star formation some 2 billion to 3 billion years ago, and the ejected gas cloud has since traveled 250,000 light-years to to the location where it is today.

The event may have created thousands of supernovas of the type that create the overabundance of silicon, said Keeney. “Two to three billion years is plenty of time for stars in the ‘starburst galaxy’ to die and create supernovas, and for the gas to reach its current location between us and 3C273.

“Because the large numbers of supernovas made by the dwarf’s starburst blew all of the gas into the surrounding intergalactic space, there likely will be no further star formation in the galaxy,” Keeney said. Theoretical models predict the dwarf galaxy will continue to fade to only about 10 percent of its current brightness. After another few billion years, the dwarf is expected to be so faint that it will be comparable to the smallest and faintest galaxies, known as “dwarf spheroidals.”

Not only are these small objects the most numerous of all galaxy types today, but there also may have been a much larger number of them in the past, said Stocke. Current theories of galaxy formation suggest in the early history of the universe, all stars were formed in tiny galaxies like this one, most of which then merged together and became incorporated into larger galaxies.

“So our own Milky Way probably was created by mergers of smaller galaxies like this one,” said Keeney. “If this is correct, and if all dwarf spheroidals went through an active starburst phase, a large portion of intergalactic space could have been enriched with gas without any help from more massive galaxies like the Milky Way.

“They may be tiny,” Keeney said, “but they are so numerous that their collective effects may be more important in the chemical evolution of the universe than much larger galaxies like our own.”

Project team members include Keeney, Stocke and Kevin McLin of CU-Boulder’s astrophysical and planetary sciences department, Weymann of the Carnegie Institution and Professor Mark Giroux of East Tennessee State University.

Additional observations were made with the Carnegie Institution’s Las Campanas 2.6-meter telescope in Chile and the Wiyna 3.5-meter telescope at Kitt Peak, Ariz.

Brian Keeney | EurekAlert!
Further information:
http://www.colorado.edu/

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

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: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

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....

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

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>