The telescope project led by Texas astronomers will change the way we look at the universe-Texas Monthly

2021-11-25 09:37:06 By : Mr. Hua er

Caitlin Casey of UT will use the Webb telescope to observe conditions nearly 14 billion years ago.

In March last year, astronomer Dr. Caitlin Casey of the University of Texas at Austin was holding a two-month-old baby under the haze of early pregnancy when she received an email similar to winning a prize. The "First Cycle JWST Notification Letter" is the subject line. Opening it, she read: "We are pleased to inform you that your proposal for the first cycle of the James Webb Space Telescope title Universe Webb has been approved..." 

She doesn't need to read on anymore. Officially recognized! She knows what it means. She slammed her laptop shut and sent a message to her colleague Jeyhan Kartaltepe, an astrophysicist at Rochester Institute of Technology. "We got it—oh my god, we got it," Casey typed.

"No!" Kartaltepe replied, dumbfounded.

What Casey gets is the long-awaited largest project of the new James Webb Space Telescope, which is scheduled to launch from French Guiana on December 18. Weber, the world's most powerful telescope, promises to change the way we understand the universe. Naturally, astronomers from all over the world, hoping to obtain valuable research time, submitted proposals to the Space Telescope Science Institute (STScI). In an email in March, the center gave Casey and her team more time than any other team.

At the age of 36 when he received his Ph.D. in 11 years, Casey is relatively young and can receive such an honor. But she has other reasons to be surprised. Her proposal, COSMOS-Webb — which she and Kartaltepe co-authored during the pandemic in a Zoom conversation with dozens of colleagues around the world who will be participating with them on the project — is almost absurdly ambitious. The traditional view of the Webb telescope is to observe a small part of the sky deeply, one arm apart as large as the tip of a needle, while Casey and Kartaltepe asked to see a much larger patch, an average of three per night. The size of the full moon. STScI granted them 218 hours or approximately eight days of telescope time. ("Most shows are within 6 hours," she said.) If all goes well, the generated images and data will directly reach the door of the big bang nearly 14 billion years ago, showing a magical but mysterious period. The dark, turbid atoms are ionized by the first light sources.

In October last year, I met Casey in Casey’s small office. She is located on the 16th floor of UT’s towering Physics, Mathematics and Astronomy Building. There is a huge dry erase board that covers almost half of the wall and is full of equations. She teaches very quickly and can easily draw metaphors that laymen can understand, exuding excitement that a few cups of coffee can't make, smiling like sharing exciting gossip, and saying, "We are starting to think about the beginning of time, right Bar?"

When Casey received her PhD at Cambridge University in 2010, when she first focused on the blurry early universe, most of what we know was shaped by NASA’s Hubble Space Telescope-this is the main A pioneering device for measuring starlight. Using Hubble, astronomers can clearly see starlight in the observable universe, including images almost dating back to the Big Bang. But it is far from enough to see those earliest years. (One of the more exciting things about powerful telescopes is that they allow a kind of time travel: Since light from faraway places takes many years to reach the earth, and the universe is expanding, Weber will show us the history of images from the universe, Because it explores space more and more deeply.) "We think we have a good understanding of the past 1 to 11 billion years," Casey said. "But in the first billions of years, you start to encounter really interesting problems that challenge our view of how physics works. Many macro problems are a bit like chicken and egg problems."

In the universe, the problem of chickens and eggs is this: we know that stars are born from gas, and when stars die, gas will condense and start the cycle again. However, scientists want to know, how did this process begin? Hubble provides images of some early galaxies—the oldest galaxies are 400 million years after the Big Bang—giving astronomers a glimpse of what that era might be like. Nevertheless, the sample is too small to draw a clear conclusion. To further explore that period, astronomers need a telescope that works mainly at infrared wavelengths, because the light from distant galaxies is stretched, or "redshifted" into infrared light during its journey to us. 

Enter the revolutionary James Webb Space Telescope. In 1996, Casey was about 11 years old, when scientists formally recommended the infrared telescope as NASA's next major project. In the following decades, a team of more than 1,200 scientists and engineers from 14 countries has been pushing the limits of technology to create it. The $9.7 billion observatory is operating in the cold minus 370 degrees Fahrenheit so that its infrared sensors can work properly. After launch, it will settle in space and unfold its 18-sided gilded six sides at a distance of 1 million miles from the earth. Shaped mirror. It must work perfectly; if there is any problem, the telescope is too far away to be repaired. "We are all very nervous about this," Casey said, noting that the binoculars' shading layer can block the sun's light and heat and is as thin as a person's hair. "Oh, my goodness, this is terrible for me. Yes, I'm glad I didn't work for it, and I don't have to think about it." 

Like all astronomers, Casey has been looking forward to Webb's arrival for many years. Weber will multiply by the order of magnitude the number of star coefficients we can see from the earliest era of the universe. It will also provide clearer data on some of the biggest astronomical issues, such as questions about the life cycle of stars, the behavior of galaxies over time, planets outside the solar system, and evidence of life beyond Earth. Using the telescope as expected, most of the research will focus on tiny points and go as deep as possible. (This is the case with Casey’s UT colleague Steven Finkelstein, who will investigate the early era of light for approximately one hundred hours for the Webb Deep Extragalactic Exploration Public [WDEEP].)

But Casey's unconventional proposal promotes the idea that instead of going narrowly to the ground, it is important to have more background and investigative vast areas to piece together mosaics. She described the structure of the universe as spongy, and she explained that some regions are like pockets, or voids without galaxies, while other regions are like knots with thousands of dense galaxies. Without a broader view, a point in space may lead to wrong conclusions. "You might think,'Well, oh, you know, galaxies didn't exist at that time in the history of the universe,'" she said. "But you could have landed in the void." 

Although most of her observation plans will not take place until April 2023, Casey's preparations are underway. She will collect data from observatories around the world and prepare for receiving the long-awaited images and data. She predicts that when the survey is conducted on eight key days, she will discover about one million galaxies-four to five thousand of which formed during the reionization era. Hundreds of millions of years after the Big Bang, when the universe is mainly composed of neutral hydrogen, cooling and expanding, gas clouds begin to collapse under their own gravity and form stars, slowly but surely turning a very foggy place into a clearer place The place where there is light to travel freely. "We can use this data to refine our model of how we think the universe actually formed," Casey said. "Yes. This is a big deal."

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