STATES CHRONICLE – Astronomers discovered that ancient stardust might help them reveal how the first stars managed to form. They used ALMA in the Chilean Andes. ALMA represents the Atacama Large Millimeter/submillimeter Array which has helped astronomers make several groundbreaking findings since it was brought online back in 2011. ALMA is bound to provide images of the sky at submillimeter and millimeter wavelengths, tracing emissions which are associated with dust and molecular gas.
These celestial objects are cold and can be hard or impossible to be detected at other wavelengths. By implementing this ability, ALMA had tracked gas and dust in a galaxy which formed when our universe was only 4% of the age it is now. The galaxy is known as A2744_YD4 being the most distant galaxy which was ever discovered by ALMA.
It appears at a redshift of 8.38, which is related to a time when the universe was only six hundred million years old. Redshift is bound to measure the amount by which the light of a faraway object is stretched by the expansion of the universe. Celestial objects which have a higher redshift appear to be farther away. Thus, we see them as they were in the past.
In the nearby universe, cosmic objects seem to have a redshift close to zero. A galaxy like A2744_YD4 has situated very far away, the exact distance depending on the universe’s expansion history. Scientists highlight the idea that redshifts are not linear. Those redshifts which measure 0-1 are known to be relatively close while the ones of 8-9 are among the farthest objects we can see when looking back at the early formation stages of the universe.
The cosmic microwave background was developed at a redshift of approximately 1,000. A2744_YD4’s cosmological mark as provided by its redshifts is categorized as being included in the Epoch of Reionization. That age occurred around a redshift of 10 when the universe was approximately four hundred million years old. The Epoch of Reionization is when the first sources of light of the universe, such as galaxies, quasars, and stars, had ionized neutral hydrogen atoms.
Neutral becomes opaque in front of short wavelengths of light. This means that it absorbs the wavelengths very easy in such a way that the light is not able to pass through.
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