Monster galaxies’ blasts superheated early universe
By ANISaturday, October 9, 2010
WASHINGTON - New Hubble observations have suggested that monster galaxies with supermassive black hole hearts released fierce blasts that superheated the early universe.
The scorching conditions also stunted the growth of smaller dwarf galaxies, the new research has shown.
Between 11.7 to 11.3 billion years ago, ultraviolet (UV) light emitted by quasars-enormous galaxies with supermassive black holes at their centers-stripped electrons of cosmic helium, according to observations made with the Cosmic Origins Spectrograph (COS) on NASA’s Hubble Space Telescope.
The big bang that created our universe occurred around 13.7 billion years ago.
The electron-stripping process, known as ionization, heated the helium gas from 18,000 to nearly 40,000 degrees Fahrenheit (10,000 to 22,000 degrees Celsius).
Warm gas moves faster than cool gas, and the heated helium sped free of the gravitational clutch of so-called dwarf galaxies.
“During this time, dwarf galaxies didn’t get fed very well,” the National Geographic News quoted study leader Michael Shull as saying.
With Hubble’s help, Shull and his team detected a specific wavelength of UV light emitted from distant quasars about 11 billion years ago.
Light emitted from farther away, and thus older, quasars lacked this wavelength, because the light was getting absorbed by neutral helium as well as helium with a single ion-or charged particle.
The helium gas became transparent to the UV light only when the helium became double ionized. By determining when this transition took place, scientists can pin down the start date of the helium-ionization era.
“A lot of them held on to their cores, and they had to wait until this period was done before they could start bringing in gas again,” said Shull.
A similar phenomenon happens to the planets of our solar system, Shull added.
The research would be published in The Astrophysical Journal. (ANI)