Astronomers Measure All Of The Starlight Produced By Observable Universe

Posted: Dec 1 2018, 4:07pm CST | by , Updated: Dec 1 2018, 4:17pm CST, in Latest Science News


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Astronomers Measure All of the Starlight Produced by Observable Universe
This map of the entire sky shows the location of 739 blazars used in the Fermi Gamma-ray Space Telescope's measurement. Credit: NASA/DOE/Fermi LAT Collaboration

Data from Fermi telescope allow researches to measure the entire amount of starlight ever emitted.

Researchers using data from NASA's Fermi Gamma-ray Space Telescope have measured all of the starlight ever produced in the observable universe. The results provide new insight into the formation of stars and could help us explore how the first stars were born in the universe.

It is believed that universe is about 13.7 billion years old and that the first stars would have been born about 100 million years after the universe began. The formation of those first stars and the light produced by them had a dramatic effect on the universe. There are now about a trillion-trillion stars and two trillion galaxies.

"From data collected by the Fermi telescope, we were able to measure the entire amount of starlight ever emitted. This has never been done before," said lead author and Clemson College of Science astrophysicist Marco Ajello. "Most of this light is emitted by stars that live in galaxies. And so, this has allowed us to better understand the stellar-evolution process and gain captivating insights into how the universe produced its luminous content."

The light emitted by objects like stars and galaxies continues to travel throughout the universe but it is impossible to directly measure it due to the luminosity of our own sun and Galaxy. Besides our galaxy, the rest of the starlight that reaches Earth is exceedingly dim. It is equivalent to a 60-watt light bulb viewed in complete darkness from about 2.5 miles away.

In order to establish the total amount of light from all of the stars in the observable universe, researchers make use of most energetic form of light called gamma rays which provide an alternative, indirect method of measuring starlight.

NASA's Fermi Gamma-ray Space Telescope, launched in 2008, observes the entire sky in high-energy gamma rays and provides enormous amounts of data on gamma rays and their interaction with the extragalactic background light (EBL), a kind of cosmic fog. When gamma ray photons produced by blazars or galaxies containing supermassive black holes collide with the cosmic fog, they leave an observable imprint. By measuring how many gamma rays photons have been absorbed, researchers measured how thick the fog was and how much visible and ultraviolet light emitted by stars was there.

In the latest effort, researchers performed the gamma ray analysis of all 739 blazars, whose black holes are millions to billions of times more massive than our sun.

“By using blazars at different distances from us, we measured the total starlight at different time periods," said researcher Vaidehi Paliya of the department of physics and astronomy. "We measured the total starlight of each epoch—one billion years ago, two billion years ago, six billion years ago, etc. - all the way back to when stars were first formed. This allowed us to reconstruct the EBL and determine the star-formation history of the universe in a more effective manner than had been achieved before."

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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