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 Porous graphene ribbons doped with nitrogen for electronics and quantum computing
09.07.2020 | University of Basel

nachricht Rock 'n' control
09.07.2020 | University of Göttingen

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: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Porous graphene ribbons doped with nitrogen for electronics and quantum computing

09.07.2020 | Physics and Astronomy

Record efficiency for printed solar cells

09.07.2020 | Power and Electrical Engineering

Rock 'n' control

09.07.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>