JENAM: New Results on Dwarf Galaxy Evolution

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JENAM: New Results on Dwarf Galaxy Evolution

Post by bystander » Fri Sep 10, 2010 9:28 pm

New Results on Dwarf Galaxy Evolution
Joint European and National Astronomy Meeting 2010 | 10 Sept 2010

The 'Local Cosmology from Isolated Dwarfs (LCID)' team showed their most recent results that suggest that reionization alone is not able to stop star formation in Dwarf Galaxies, as had been expected. The results were presented yesterday during the European Week of Astronomy and Space Sciences.


The Big Bang model predicts that the universe started out as completely ionized plasma, which later cooled and allowed all of the atoms to recombine into neutral atoms. The first generation of stars and galaxies formed from this neutral material and produced high energy radiation which then ¨reionized¨ the universe. This period of reionization ended approximately 1 billion years after the Big Bang.

LCID has used over 100 orbits of the Hubble Space Telescope (HST) observing time with the ACS camera in order to obtain detailed star formation histories for six Local Group dwarf galaxies, which include details about early star formation. ...

The smallest galaxies represent important probes of the conditions of the early Universe, since their early star formation can be strongly influenced by cosmic reionization. The most common prediction of models of dwarf galaxy evolution is that the early ionization of the gas in these galaxies by the cosmic UV background should have halted and prevented any subsequent star formation in them after about 12.5 Gyr ago. The paper was published this week in the Astrophysical Journal.

Credit: NASA/LCID
The ACS LCID Project. III. The Star Formation History of the
Cetus dSph Galaxy: A Post-reionization Fossil
- M Monelli et al

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