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Early discoveries from the HERA telescope promise a deeper understanding of the dawn of the universe.

Part of the HERA radio interferometer array in the Karoo Desert, South Africa, under early construction in 2016, taking pictures with the on-site crew. Credit: Kathryn Rosie

Throughout history, humans have created and shared stories that ponder the creation of stars — what they are and what the first stars have become. With new results from the hydrogen epoch (HERA) of the reionization array, a radio telescope now in the Karoo Astronomy Reserve in South Africa, MIT scientists have taken a small but important step in understanding its history. I did.


HERA researchers are looking for the earliest signs of star formation and galaxy structure. Specifically, scientists, including Jacqueline Hewitt, MIT’s professor of physics Julius A. Stratton, will understand what happened at what was called the dawn of the universe, about 400 million years after the Big Bang. It is said that. In early fall 2021, Hewitt, Nicholas Kern, MIT Kaburi Astrophysics and Space Institute Physics Paparald Fellow, and other researchers in international cooperation have long-awaited collection and analysis over a four-year period in the first phase. Completed the result. Of the structure of the telescope.Their study was published on February 7th Astrophysical JournalPresents a new upper limit to Wireless signal From hydrogen in space. This shows early star formation and provides scientists with a clearer image of when the first stars and galaxies were formed. These discoveries narrow down theoretical models that assume the origin of the dawn of the universe.

The findings of HERA were partly very important as they were collected very early in the development of HERA. The telescope, which acts as a series of radio dishes, is currently located in only a small part of its final size. Data was collected from 39 of HERA’s 52 deployed antennas. In full form, there are a total of 350 antennas. When fully constructed, HERA can go back in time because it is sensitive enough to collect larger datasets and information from a distance.

“We haven’t done everything we can yet,” says Khan, the lead author of the paper. “This result is a demonstration of the telescope as an entity. It is a demonstration of the first path in the analysis of data. It is a kind of framework and the basis for all future analyzes.”

Seeking a signal

To look back at the dawn of the universe, HERA uses low-frequency radio waves to identify signals that are not easily observable. This is unlike other telescopes that observe galaxy-like structures that make up only 5% of the observable matter in space, such as the Hubble Space Telescope. The other 95% of matter is between galaxies containing low-density hydrogen. With HERA, scientists look at what’s happening between galaxies and use that information to see what unobservable galaxies are doing and how galaxy formation affects the surrounding space. You can guess if you want to.

To understand this period in the history of the universe, scientists are looking for a “spin flip signal,” also known as the 21-centimeter line, which is the wavelength of neutral hydrogen gas. This radio signal originates from the intergalactic medium between galaxies and is generated by the emission and / or absorption of hydrogen atoms emitted by this transition.

“What we see at HERA is what spinflip signals look like in this era.” Principal theorist at the HERA project and associate professor of physics and astronomy at the University of California, Los Angeles. Steve Furlanetto says.

He says it’s important to identify the era of reionization of the universe, when signals are observed. “We want to know [the signal] During absorption, that is, before X-rays, or during emission, that is, after X-rays. And I want to see if it disappears due to reionization. ”

The signal has two signatures or processes that can be captured. When the star heats the hydrogen gas, the signal changes first. The second part HERA has been looking for so far is the loss of the 21 cm signal. This occurs when hydrogen is ionized by the energy generated by the additional star formation. This signature indicates that the star has been created.

21 cm line from The dawn of the universe Not yet clearly detected. However, HERA’s new results provide data on the nature of spinflip signals since the universe was 500 million years ago (10 times more sensitive than previous results).

Glimpse

These results provided evidence that the HERA team ruled out some possible theories about galaxy formation. Most notably, the data show that there must have been some mechanism for heating hydrogen in the universe. That is, the galaxy must have a black hole.

“If you have a galaxy without a black hole, that’s basically something you can exclude,” says Furnaletto. “Heating is required. This means that in the context of these models, there must be a black hole near where the X-rays are generated.”

Funded by the Gordon and Betty Moore Foundation and the National Science Foundation, HERA operates with 350 antennas and a new antenna design that allows the telescope to capture lower frequency radio waves and display points at higher red shifts. increase. time.

Hewitt, project leader on HERA’s signal capacity expansion, has been addressing the question of when the earliest stars were formed since 2004. She is leading the prototyping of new low frequency components and is developing more techniques for analyzing current and future datasets. .. The new antenna design at the University of Cambridge will be installed by early 2022, dramatically expanding the range of information available.

“The expansion to this low frequency is important because it takes us this period before the first star,” Hewitt said, explaining that expanding the range helps to learn more about the early stages of space history. To do.

“It’s amazing how it works. You’re a little tired, but sometimes I stop and think,” I’m making an instrument that looks back 13 billion years ago. ” Do you know? Hewitt said. “It’s kind of amazing that we can actually do that.”


Incredible adventure of spatula mission


For more information:
Zara Abdurashidova et al, first result of HERA Phase I: upper limit 21 cm power spectrum in the era of reionization, Astrophysical Journal (2022). DOI: 10.3847 / 1538-4357 / ac1c78

Quote: Early discoveries from the HERA Telescope were taken from https://phys.org/news/2022-02-early-hera-telescope-deeper-cosmic.html on February 11, 2022 (Dawn of the Universe). Promises a deeper understanding of (February 11, 2022)

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Early discoveries from the HERA telescope promise a deeper understanding of the dawn of the universe.

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