Wednesday, October 27, 2010
Reduce Excema Redness
If you think global warming is hard, does 11,000 million years across the universe went through what we might call a universal warming. The consequence of this initial heating was that ferocious blasts of radiation from black holes voracious stunted the growth of some small galaxies over a period of 500 million years. This is the conclusion reached by a group of astronomers led by the University of Colorado at Boulder, who used the new capabilities of the Hubble Space Telescope NASA to study the universe invisible and remote.
Using the newly installed Cosmic Origins Spectrograph, or COS, the team identified an age ago 11700 to 11.3 billion years ago when the universe started electrons primordial helium atoms - a process known as ionization. This process prevented heated intergalactic gas that collapse gravitationally to form a new generation of stars in some galaxies small. Less massive galaxies were unable even to maintain their gas, and escaped back into intergalactic space.
Professor of CU-Boulder, Michael Shull, the department of astrophysics and planetary sciences and his team were able to find the telltale sign of spectral absorption lines of helium in the ultraviolet light from a quasar - the bright core of active galaxies. The quasar shines through the clouds middle of what would be otherwise invisible gas, such as a streetlight shining through the fog. The beam allows for a core sample of the gas clouds that lie between the galaxies in the early universe.
The universe went through a wave of initial heat for about 13 billion years, when the energy from the first stars ionized hydrogen mass from the Big Bang. This time period is known as the time of Re-ionization, because hydrogen nuclei were originally in an ionized state shortly after the Big Bang, says Shull, a member of the faculty of the Center for Astrophysics and Space Astronomy CU-Boulder, or CASA.
A published article on the subject in the October 20 issue of the journal Astrophysical Journal
. The co-authors include researchers associated with France and CASA Kevin Charles Danforth, the researcher HOME postdoctoral Britton Smith and Jason Tumlinson of the Space Telescope Science Institute in Baltimore.
but Hubble data indicated that it would take another 2000 million years before the universe of ultraviolet radiation sources produce enough energy to perform the task of re-ionize the primordial helium that had been warmed by the Big Bang .
This radiation did not come from the stars, but of quasars, said Shull. In fact, the era in which the helium began to re-ionization corresponds to a transitional period in the history of the universe in which the quasars were plentiful.
The universe was a busy place then, said Shull. Galaxies that collided with increased frequency and supermassive black holes at the cores of galaxies with gas falling inside. Black holes became wildly part of the gravitational energy of this mighty mass of far-ultraviolet radiation that would be thrown out of galaxies. This heated the intergalactic helium from 8000 levels to almost 22000.
After helium reionization, the intergalactic gas was cooled again and the dwarf galaxies could continue its normal assembly. "I imagine that could have formed a few dwarf galaxies if there were no taken place re-ionization of helium, "said Shull.
So far, Shull and his team have only one line of sight from Hubble to measure the transition of helium, but the COS science team plans to use Hubble to look in other directions and see if the re-ionization of helium took place uniformly throughout the universe.
Author: Jim Scott
Original Date: October 7, 2010 Original Link
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