Astronomers said on April 7, 2022, that they had discovered the most distant astronomical object ever observed. They believe that this object is a galaxy and, if so, it is the most distant known at the moment. The item is labeled HD1. It is 13.5 billion light-years away. Because light does not travel infinitely fast, but takes time to travel in space to us, looking out into space is the same as looking back in time. So, said these astronomers, we are looking at this object as it existed in the distant past, just 300 million years after the Big Bang in which our universe was born. Yuichi Harikane of the University of Tokyo discovered the galaxy. He said: It was very hard work to find HD1 from more than 700,000 items. The red color of HD1 matched the expected characteristics of a galaxy 13.5 billion light-years away, causing me to shudder when I found it. The scientists published their study of this new object, HD1, in the Monthly Notices of the Royal Astronomical Society Letters on January 3, 2022, and in the Astrophysical Journal on December 16, 2021.
The farthest object and the farthest galaxy
An international team of astronomers used a series of telescopes to locate this distant object. The Subaru Telescope, the VISTA Telescope, the United Kingdom Infrared Telescope, and the Spitzer Space Telescope all looked at the same point in space for a total of 1,200 hours. Once they located the dim red object shown in the image above, they made subsequent observations with the Atacama Large Millimeter / submillimeter Array (ALMA) array to confirm the distance. The previous record holder for the farthest object went to GN-z11, a galaxy we see in the direction of the Big Dipper. Shifting to red z = 11.09, GN-z11 is 13.4 billion light-years away. It exists about 400 million years after the Big Bang. HD1 is 100 million light-years away from GN-z11. View larger. | This timeline shows you how far back in time this recently observed galaxy was. We see it as it was almost 300 million years after the Big Bang. Image via RAS.
An ultraviolet-bright object
Scientists believe that this object, the most distant ever seen in space, is a galaxy in the infant universe. We can see the object because it is extremely bright at ultraviolet (UV) wavelengths. Why is it so bright in ultraviolet light? Astronomers have two ideas.
Idea 1: Population III starred in the most distant galaxy
First, the galaxy can form stars at a furious rate. These could be some of the first stars in the universe. Astronomers would categorize these early stars as Population III stars. Population III stars are a hypothetical category because they have never been observed to be so far back in time. They would be extremely massive, hot, bright stars that created the first chemical elements heavier than hydrogen. Scientists estimate that HD1 forms more than 100 stars each year. This rate is at least 10 times higher than a normal galaxy with a stellar explosion. This is one of the reasons why the galaxy does not form “normal” stars. Lead author Fabio Pacucci of Harvard University and the Smithsonian Astrophysical Observatory said: The first star population to form in the universe was larger, brighter, and warmer than modern stars. If we assume that the stars produced in HD1 are these first stars or Population III, then its properties could be more easily explained. In fact, the stars of Population III are capable of producing more ultraviolet light than normal stars, which could clarify the extreme ultraviolet brightness of HD1.
Idea 2: An oversized black hole in the most distant galaxy
Second, the galaxy may be home to an oversized black hole. It should be about 100 million times the mass of our sun. Compare that to the oversized black hole at the center of our galaxy, which is about 4 million times the mass of our sun. The oversized black hole will eat up the surrounding material and, in the process, emit high energy photons. If it were an oversized black hole, it would be the earliest ever seen, much closer in time to the Big Bang than the current record holder. Harvard Avi Loeb commented: Formed a few hundred million years after the Big Bang, a black hole in HD1 must have grown from a huge seed at an unprecedented rate. Once again, nature seems to be more imaginative than we are.
Understanding an object from the whole universe
Pacucci explained how difficult it is to analyze an object that exists so far away. He said: Answering questions about the nature of a source so far away can be challenging. It is like guessing the nationality of a ship from the flag it carries, while it is on a distant shore, with the boat in the middle of a storm and dense fog. One can see some colors and shapes of the flag, but not all of them. It is, after all, a long game of analyzing and excluding improbable scenarios. The team hopes to use the Webb telescope to make subsequent observations and confirm the identity of HD1 as the most distant galaxy ever discovered. Conclusion: An international team of scientists has discovered the most distant astronomical object ever seen. HD1 – as it is called – is believed to be the most distant galaxy known to date. Source: A Search for H-Dropout Lyman Break Galaxies at z ~ 12-16 Source: Are the recently discovered sources of abandonment z ~ 13 Starburst galaxies or quasars? Through the Royal Astronomical Society
Kelly Kizer Whitt
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Kelly Kizer Whitt is a science writer specializing in astronomy for more than two decades. She started her career at Astronomy Magazine and has made regular contributions to AstronomyToday and the Sierra Club, among others. Her children’s picture book, Solar System Forecast, was published in 2012. She has also written a dystopian novel for young adults entitled A Different Sky. When she is not reading or writing about astronomy and looking at the stars, she enjoys traveling to national parks, creating crossword puzzles, running, tennis and paddleboarding. Kelly lives with her family in Wisconsin.
