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SNHS Spotlight: Quasar P172+18

Astronomers discovered the universe’s oldest known source of radio emission located 13 billion light years away. This source is known as a quasar. Quasars make up the cores of galaxies where a black holes devour all of the matter that is unable to escape its gravitational grasp. While this is occurring, an immense amount of radiation is emitted. This amount of radiation is over a trillion times brighter than the brightest stars, which makes quasars the brightest objects in the known universe.

Satellite image of Quasar P172+18 credits to

The Big Bang Theory is the leading explanation about how the universe began. It states that the universe began with a small singularity, then expanded over 13.8 billion years to the cosmos that we know today. The discovered quasar, named P172+18, is from around 780 million years after
the Big Bang. It reveals clues about the “epoch of re-ionization”, one of the earliest stages of the universe. Re-ionization is the process by which matter in the universe was re-ionized. At the beginning of this period, the universe was surrounded by a cloud of hydrogen gas and was extremely dark because most light was quickly absorbed by the neutrally charged gas. Over time, gravity caused the gas to collapse, forming stars and quasars which allow light to pass through.

An astronomer at the European Southern Observatory in Chile named Mazzuchelli and an astronomer at the Max Planck Institute for Astronomy in Germany named Bañados first spotted the quasar while using the Magellan Telescopes at Las Campanas Observatory in Chile. They observed the radio signature left by powerful jets of particles erupting from above and below the black hole. The particles emit a tremendous amount of radio waves.

P172+18 is nearly 300 million times bigger than the sun and is among the fastest-growing quasars ever discovered. Scientists don’t know how a black hole became so massive this early on in the universe. The radio jets are a possible explanation.

“Theoretical studies say that the presence of radio jets can increase the speed of which the black hole eats matter, which means that they can allow for a black hole to grow much faster and might explain why [the black holes] are so massive so early,” Mazzucchelli said. “At the same time radio jets may also impact the galaxy surrounding the quasar by influencing how stars form.” When the astronomers compared their most recent observations to a survey of the sky taken more than two decades before, they discovered that the quasar had lost half its brightness, hinting that the quasar was possibly reaching the last stages of its life.

Works Cited

By: Abby Benus’ 22, SNHS Member

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