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 NASA Hubble Space Telescope Collection |
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The universe is expanding, and from far, far away in space and time, astronomers can see the formation of massive galaxies. These bright clusters of stars more than a few million light years away appear redder (or redshifted) than closer stars which helps in determining their distance and thus, time, in the development of the universe. Astronomers study these distant massive galaxies to better understand the timescale of galaxy formation and how galaxy shapes are formed, such as disks and bulges.
Observation of some of these massive galaxies in the early Universe (known as sub-millimeter galaxies due to their wavelength, or high redshift) has revealed a very high rate of star formation, higher than expected from models. One hypothesis for this fast rate is the possibility of the merging of two gas-rich galaxies. Direct examination of the star-forming regions of these very distant galaxies has been difficult due to the limitations of modern-day telescopes.
In a paper published this week online in Nature, a group of scientists, including two from the Department of Astronomy at the University of Maryland, use a unique solution to study one of these massive galaxies from the young Universe. By studying a sub-millimeter galaxy (known as SMMJ2135-0102), they took advantage of strong gravitational lensing that magnifies the galaxy from the bending of light by massive galaxy clusters that lie behind them. With this magnification, they then used high-resolution sub-millimeter imaging to resolve the star-forming regions at a linear scale of only 100 parsecs (one parsec is about 3.26 light years or 31 trillion kilometers), only slightly higher than the resolution of viewing giant molecular clouds in our own Milky Way.
By comparing brightness and size between the high redshift galaxy and local galaxies and molecular clouds in the present-day Universe, the researchers found that the star forming region was not only 100 times larger, but also 100,000,000 times brighter. And although the star-forming energetics are much higher than local galaxies, the underlying physics of the processes are the same. Because the physics are similar, this means that techniques used for star-forming processes in the Milky Way can be used for sub-millimeter galaxies.
So physics has not changed between the early Universe and the present-day Universe — young Universe galaxies are just really, really big, bright, and productive.
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