It's Supernatural

Author: Bryan Lin

Editors: Misha Wichita and Ruoxi Lin

Artist: Kevin Lin

As the most powerful phenomenon in the Universe, gamma-ray bursts are both a magnificent once-in-a-lifetime event and a valuable tool in expanding our knowledge of the universe. Gamma-ray bursts are short explosions of high-energy light that produce an afterglow of different types of electromagnetic radiation. Yet, what precisely is a gamma-ray burst? How do these bursts impact us and how do they assist astronomers in charting our galaxy?

First observed in 1900 by French chemist Paul Villard, gamma-ray bursts are a brief expulsion of energetic gamma-rays that causes an explosion whose brightness is akin to a million suns. This explosion emits such an astonishing quantity of energy in just a matter of seconds yet manages to surpass the sun's energy production over a span of 10 billion years. Astronomers at NASA and across the world believe that these bursts are the effect of a supermassive star’s core running out of fuel and collapsing in on itself, forming a black hole. Typically, stars gradually consume the fuel that prevents them from collapsing under their gravity as they age. But when they can no longer produce enough fuel, gravity emerges victorious. The hot gas star then condenses into an even hotter, denser state from its inward collapsing, causing the gamma-ray burst. While the collapse of a massive star is not the only cosmic event that can cause these powerful gamma-ray bursts (the collision of two neutron stars can also result in this), it's undoubtedly the most powerful. It is important to note that while the collapse of massive stars causes gamma-ray bursts, not every death of a massive star will cause them.

Given its immense power, you may wonder why a gamma-ray burst has not already destroyed Earth. Unfortunately, it is not because Earth possesses a kind of immunity against these bursts, but rather because they have yet to come close enough to have a significant impact on the planet so far. It is known that gamma-ray bursts can vaporize anything within 200 light-years of them, but the closest occurrence of a burst to Earth is approximately 1300 million light-years away. However, if Earth were to be caught in the path of a gamma-ray burst, the consequences would be devastating. A continuous beam of gamma-rays would result in sterilizing all matter it comes in contact with; resembling a disinfectant, it would eradicate DNA and inflict harm upon tissue, like a UV wand eliminates germs on medical equipment. Essentially, no living thing above ground would survive, and familiar ecosystems would suffer severe damage if the planet had not already vaporized in the wake of the explosion. Despite the distance between these bursts and Earth, some questions remain about if the planet has remained completely unscathed by these intense gamma rays. The infamous Ice Age, which wiped out two-thirds of animal life, is one event in our history that may have resulted from a gamma-ray burst. Furthermore, while Earth's atmosphere serves as a protective barrier against a significant amount of radiation, it is not entirely immune to gamma-rays. When exposed to gamma radiation, oxygen and nitrogen molecules can become ionized which leads to increased levels of nitrous oxides. This particular gas is believed to block out sunlight and have a cooling effect on the planet millions of years ago during the Ice Age.

Despite gamma-ray bursts being able to annihilate the Earth, they are not entirely negative, as astronomers and astrophysicists can use the x-ray emissions they give off to map out our galaxy. As x-rays travel towards Earth, a portion of them bounce off dust layers which results in "light echoes" of the original explosion in the shape of expanding X-ray rings forming from the source of the burst. Scientists can use such light echoes to search for distant dust clouds within our galaxy. They can also use these x-rays to understand better where these dust clouds are located. The European Space Agency (ESA) has discovered the existence of 21 different dust clouds with this method and shows how gamma ray bursts have expanded knowledge of our galaxy. Additionally, since the light created from such a burst takes millions of years to travel to Earth, scientists can study the past by analyzing the illuminated sky. Since gamma-ray bursts originate from massive stars, they provide valuable information about the rate at which stars were formed in the early times of the universe.

Gamma-ray bursts are dangerous, beautiful, and scary, yet necessary. While we certainly would not want to be in the vicinity of such a powerful and rare event, it contributes to our understanding of the galaxy, such as occurrences like the conclusion of life for massive stars and the development of black holes in galaxies located far away.

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