From their labs on a rocky planet rooted in the vast universe, Clemson University scientists managed to measure all the stars that were ever created in the history of the observable universe.
Astrophysicists believe that our universe, which is about 13.7 billion years old, began to create the first stars when it was several hundred million years old. Since then, the universe has become a star tour. There are now about two billion galaxies and trillion trillion stars. Using new methods of stellar field measurement, Clemson College of Astronomy astronomer Marco Ajello and his team have analyzed NASA's Fermi Gamma-ray Space Telescope, which has identified the history of star formation for most of the life of the universe.
A joint article titled "Determining gamma radiation in the history of stars of the universe" was published in the journal. Science and describes the results and consequences of the new measurement process in the team.
"From the data collected by the Fermi telescope, we were able to measure the whole number of stars that were ever broadcast, and that never happened," said Ajello, who is the lead author of the work. "Most of this light is radiated by the stars that live in the galaxies, allowing us to better understand the process of stellar evolution and gain a fascinating insight into how the universe produces its light content."
Entering a number of stars that have ever been produced has several variables that make it difficult to quantify in simple terms. But according to the new measurement, the number of photons (particles of visible light) that escaped into space after the radiation of the stars was transferred to 4 × 10 ^ 84.
Or else: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 photons.
Despite this incredibly large number, it is interesting to note that, except for light coming from our own sun and galaxy, the rest of the light that falls on Earth is extremely subdued – the equivalent 60-watt bulb displayed in full darkness about 2.5 km away . This is because the universe is almost incomprehensibly enormous. That's why the night sky is dark except the light of the moon, the visible stars, and the dim light of the Milky Way.
The Fermi Gamma-ray Space Telescope was launched in a low orbit on June 11, 2008, and recently labeled its ten-year anniversary. It is a powerful observatory that has provided a huge amount of gamma radiation data (the most energetic form of light) and their interaction with extragalactic light background (EBL), a cosmic mist composed of all ultraviolet, visible and infrared lights emitted by stars or dust around them . Ajello and postdoctoral worker Vaidehi Paliya analyzed nearly nine years of gamma ray data from 739 blazars.
Blazars are galaxies containing supermassive black holes that are capable of releasing tightly collimated nozzles of energy particles that leap from their galaxies and intersect the universe at almost the speed of light. When one of these nozzles is directed directly to Earth, it is discovered even though it comes from far away. Gamma photons produced in nozzles eventually collide with cosmic fog and leave an observable impression. This allowed Ajell's team to measure the density of fog not only at the site but also at some point in the history of the universe.
"Gamma photons that pass through the fog of stellar light are very likely to be absorbed," said Ajello, an assistant professor at the Department of Physics and Astronomy. "By measuring how many photons we were absorbed, we were able to figure out how dense the fog was, and also measured as a function of time how much light was in the entire wavelength range."
Using galaxy research, the history of the stars of the universe has been studied for decades. One obstacle, however, faced by previous research was that some galaxies were too far or too weak to detect all of today's telescopes. This forced scientist estimates the light of the stars that produce these distant galaxies, rather than directly record them.
The Ajello team was able to circumvent this fact using Fermi's large telescope data to analyze the extragalactic background. Starlight, which escapes galaxies, including the farthest, will eventually become part of the EBL. Therefore, the accurate measurements of this recent cosmic mist eliminated the need to estimate light emissions from ultra-distant galaxies.
Palija analyzed gamma rays of all 739 blazars whose black holes are millions to billions of times more massive than our sun.
"Using lightning at different distances from us, we measure the overall star at different times," says Paliya of the Department of Physics and Astronomy. "We measured the total star of each epoch – one billion years ago, two billion years ago, six billion years ago – until the stars were created for the first time. This allowed us to reconstruct the EBL and determine the history of the star creation of the universe more efficiently than before . "
When gamma high energy collides with visible low-energy light, they transform into pairs of electrons and positrons. According to NASA, Fermi's ability to detect gamma rays across a wide range of energies, which is unique for space fog mapping. These particle interactions appear at huge cosmic distances, allowing the Ajell Group to probe deeper than ever in space-starring productivity.
"Scientists have been trying to measure the EBL for a long time, but a very clear foreground, such as the zodiac light (which is light scattered by the dust in the solar system), has made this measurement very demanding," said co-author Abhishek Desai, physics and astronomy. "Our technique is insensitive to any foreground and so overcomes all these problems at once."
Star formation, which occurs when dense areas of molecular clouds collapse and form stars, peaked about 11 billion years ago. Although the birth of new stars has slowed down since then, it has never stopped. For example, about seven new stars are created in our Milky Way Galaxy each year.
Determining not only the current EBL, but revealing its development in space history is a significant breakthrough in this area, says Diete Hartmann, a professor at the Department of Physics and Astronomy.
"Star formation is a great cosmic cycle and the recycling of energy, matter and metals, and it is the engine of the universe," said Hartmann. "Without the evolution of the stars, we would not have the essential elements necessary for the existence of life."
Understanding the origins of stars also has implications for other areas of astronomical study, including cosmic dust research, evolution of galaxies and dark matter. The team's analysis will provide future missions with guidelines for exploring the earliest days of stellar development – such as the upcoming James Webbu Space Telescope, commissioned in 2021, to enable scientists to drive initial galaxies.
"The first billion years of the history of our universe is a very interesting epoch that has not yet been explored by current satellites," concluded Ajello. "Our measurements allow us to look into it, maybe one day we'll find a way to look back to the Big Bang, that's our ultimate goal."