Why do ancient and distant gamma-ray bursts help explore the early universe?

Astronomers discover ancient, distant gamma-ray burst

An image taken by the X-Shooter instrument shows a gamma-ray burst observed by the Very Large Telescope, the red dot in the center of the image.

In September 2021, the Neil Gehrels Swift Observatory observed a gamma-ray burst that occurred in the early days of the universe while the observatory was observing the universe billions of years ago.

The event, now designated GRB210905A, occurred when the universe was barely formed, because the light from the burst took 12.8 billion years to reach Earth. Because the intense light from a gamma-ray burst and its afterglow fade quickly, astronomers quickly began to capture its residual signal, which is usually seen as an orange-red dot. According to a report, astronomers used several instruments at the Southern Observatory to capture the residual signal, such as the Very Large Telescope and X-ray Spectrometer in Chile, and the programmable telescope at the La Silla Observatory, also in Chile.

Gamma rays come from collisions between certain particles and from the nuclear decay of radioactive materials (which explains why nuclear waste is so dangerous). Astronomers believe that these powerful bursts of electromagnetic radiation occur at least once a day in the dark universe, and gamma-ray bursts are the brightest of these phenomena, but they usually don't last long.

Although gamma-ray bursts are visible to the naked eye, astronomers carefully measure how much light of different wavelengths is emitted during a burst. Like light sources in space, the light signals from a gamma-ray burst shift toward the red end of the spectrum as it travels through a vacuum. This is called a redshift. The size of the shift indicates how far away the light was, so very distant signals are converted to infrared light. This instrument allows scientists to calculate how far away the burst is and how long it took for the light to reach Earth. Such distant bursts are usually difficult to see because they are too faint, but gamma-ray bursts like GRB 210905A are very bright. If their signals are captured quickly and imaged, they will be visible.

"Gamma-ray bursts this distant are quite rare ... but they will only be a small fraction of what future missions will discover," said team leader Andrea Ross, an astronomer at Italy's National Institute for Astrophysics. Ross and his colleagues published a study on the observations on Sept. 21 in the journal Astronomy & Astrophysics.

So where does this mysterious light come from? Scientists believe that the light of this gamma-ray burst comes from matter sucked in by the huge gravity of the black hole, and have ruled out the possibility that the light comes from a magnetar. Magnetars are dead cores left behind after the death of giant stars. They are highly dense and have strong magnetic energy. The reason for this is that the energy contained in GRB210905A far exceeds the range of magnetars.

The more we know about gamma-ray bursts, the clearer our understanding of the early universe will be.

Related knowledge

Earth is the third planet from the Sun and is home to all known life in the universe. Although there is a lot of water in the solar system, only Earth's surface has liquid water. About 70.8% of the Earth's surface is made up of oceans. The rest of the rivers, lakes and polar glaciers are nothing in comparison. The remaining 29.2% is land, including continents and islands. The surface layer is made up of several slowly moving plates. These plates interact with each other, forming mountains, volcanoes, and terrible earthquakes. At the same time, the Earth's liquid outer core generates a magnetic field, which supports the entire Earth's magnetosphere and protects us from the solar wind.

La Silla Observatory is located in Chile and has three astronomical telescopes built and operated by the Southern Observatory. There are also several other telescopes located here, which are partially maintained by the Southern Observatory. La Silla Observatory is one of the largest observatories in the Southern Hemisphere and the first observatory used by the Southern Observatory in Chile.

BY: Elizabeth Rayne

FY: taokesasi

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