2020-07-16

A distant gamma-ray burst was discovered 10 billion light years away, when the universe was only 3.8 billion years old

By yqqlm yqqlm

The greater the distance in the universe, the darker it looks, and some are even detectable through large telescopes. When the astrophysics team detected the afterglow of a gamma-ray burst (SGRB) 10 billion light years away, these Astronomers are surprised. After all, afterglow is already an incredibly weak and fast signal (sometimes only lasting a few hours). The gamma-ray burst named SGRB181123B occurred 3.8 billion years after the Big Bang (that is, 10 billion years ago).

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This is the second farthest detected so far Gamma ray burst is also the farthest event with optical afterglow. Senior author of the study, Fang Wenhui of Northwestern University said:Of course we did not expect to find distant gamma-ray bursts, because they are extremely rare and very weak, and use the telescope to”forensic” to understand its environment. , Because of the appearance of its parent galaxy, can tell us a lot of potential physical information about these systems, the study’s first author Kerry Paterson (Kerry Paterson) said:

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As far as the gamma ray burst is concerned, we are uncovering the tip of the iceberg, which prompts us to study further Past events, and pay close attention to future events, whose research was published in the journal Astrophysics. Wenhui Fang is an assistant professor of physics and astronomy at Northwestern University Weinberg School of Arts and Sciences, and a member of Ciera (Interdisciplinary Exploration and Research Center for Astrophysics). Patterson is a postdoctoral assistant to Siella. Gamma-ray bursts are some of the most powerful and brightest explosions in the universe, most likely when two neutron stars merge.

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This merger will cause a short burst of gamma rays, Gamma rays are the highest energy form of light. Astronomers can usually detect 7 to 8 well-positioned gamma-ray bursts each year for further observation. Since their afterglow usually disappears for at most a few hours, they rarely stay long enough, so it is difficult to collect more information. But with SGRB181123B, astronomers are lucky. NASA’s Neil Gales Swift Observatory detected this incident for the first time.

A glimpse of the noon of the universe

In a few hours, the Northwestern University research team used Gemini-North on the top of Mauna Kea, Hawaii The telescope remotely visited the International Gemini Observatory. Using this 8.1-meter telescope, the researchers measured the optical afterglow of the SGRB181123B gamma-ray burst. Through follow-up observations using the Chilean Gemini-South, Arizona MMT and Hawaii Keck telescopes, the researchers realized that SGRB181123B may be farther away than most stars.

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Only a few hours after the discovery of the short gamma ray burst He made an in-depth observation. The images observed by the Gemini Observatory are very clear, allowing astronomers to pinpoint the location of a particular galaxy in the universe. To reveal the distance between the gamma-ray burst and the Earth, the research team then visited a near-infrared spectrometer at the South Observatory in Gemini, which can detect redder wavelengths. By capturing the spectrum of the host galaxy, the researchers realized that they had accidentally discovered a distant gamma-ray burst.

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After determining the host galaxy and calculating the distance, study The team was able to determine the key attributes of the parent constellation in the galaxy that produced this event. Because when the sgrb181123b gamma ray burst appeared, the age of the universe was only 30%of its current age, this is a period called”noon of the universe”, which provides a rare opportunity to study the neutron star when the universe is still a”teenage” merge. When a gamma-ray burst occurs, the universe is very busy, with rapidly forming stars and rapidly growing galaxies.

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The birth, evolution and demise of massive double stars take time, Eventually it becomes a pair of neutron stars that eventually merge. How long it takes for neutron stars (especially those that produce gamma-ray bursts to merge) to be merged is unclear long ago. At this moment in the history of the universe, the discovery of gamma-ray bursts caused by the merger of neutron stars shows that When the universe is forming a large number of stars, the pair of neutron stars may have merged together quite quickly.

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Bokeyuan|Research/From:Northwest University

Reference periodical “arXiv” and “Astrophysics”

Cite:arXiv:2007.03715

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