A team of astronomers looking deep into the skies has found the earliest, most distant galaxy yet, which is at only 670 million years from the big bang.
The discovery, described in Astrophysical Journal Letters, shows a surprisingly bright and active galaxy near the dawn of the universe that could answer questions on what the cosmos, which is 13.8 billion years old, looked like in its young years.
“We’re actually looking back through 95% of all time to see this galaxy. It’s really a galaxy in its infancy, when the universe was in its infancy,” said study coauthor Garth Illingworth, an astronomer at UC Santa Cruz.
Capturing an snapshot from a far-off light source is a form of looking back in time. When we gaze at the sun, we see an image of what the star looked like eight minutes ago. The same principle is valid for the light emitted by the galaxy called EGS-zs8-1, which makes the snapshot roughly 13.1 billion years old.
EGS-zs8-1 is so distant in space that the light which was caught by scientists is very faint. However, compared with other far away galaxies, it’s surprisingly bright and active, creating stars at more than 80 times the pace the Milky Way does right now. This little galaxy has built up approximately 8 billion suns’ worth of mass, 15% more than the mass of the Milky Way.
“If it was a galaxy near the Milky Way [today], it would be this vivid blue color, just because it’s forming so many stars,” Illingworth said.
One of the many problems with the search for such faint distant galaxies is that it’s very difficult to tell if they’re bright and far away, or dim and close. Astronomers can usually understand more about these galaxies by measuring the level of stretching of the distant starlight, which is “red-shifted” from higher-energy light like ultraviolet down to optical and ultimately infrared wavelengths. The cosmos is expanding faster and faster. Scientists discovered that the farther away a galaxy is right now, the faster it is moving and the wavelength of light it will be more stretched in its case.
The astronomers examined the faint light from EGS-zs8-1 galaxy using NASA’s Spitzer and Hubble space telescopes. Early galaxies, such as this one, are “probably the source of ultraviolet radiation that ionized the whole universe,” Illingworth said.
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