When the universe was only a billion years old, a galaxy spewed a gigantic, fast-moving beam of radiation and plasma into the cosmos. Almost 13 billion years later, that jet is visible to humans in the form of a blazar. The jet has recently been imaged and analyzed by a team of Italian astronomers. Their findings, which give an idea of the jet’s length and speed, were recently published in the journal Astronomy and Astrophysics.
Viewed by the Very long baseline array—A formation of 10 radio telescope antennas stretching from St. Croix in the Atlantic to Hawai’i’s Mauna Kea in the Pacific – the blazar looks like a galactic smear of tomato sauce on the cosmic lens. However, what is captured in the false-color image is a bright orange beam of plasma roughly pointed towards us and about 1,600 light-years long, a distance that defies any Earth analogy.
According to Cristiana Spingola, an astronomer at the University of Bologna and lead author of the recent paper, scientists don’t see as many blazars as would be expected in the early universe.
“Between the different scenarios, this discrepancy may be due to the distant blazars having different characteristics from the local blazar population, such as the jet moving slower than what is happening locally,” Spingola wrote in an email. “This is what our findings suggest. If confirmed, we would have found that the local and distant blazars are different beasts. “
Such jets are emitted from the centers of galaxies by supermassive black holes. The black holes collect discs of matter around them and sometimes eject jets of material at extraordinary speed. These galactic centers, called active galactic nuclei, are all known as quasars; when the rays they cast are directed towards us, they are called blazars.
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A few years ago, blazars turned out to be the sources of cosmic ultra-high energy, transforming them from an object of intrigue into a compelling source of information about the early universe. The recently described blazar, PSO J030947.49 + 271757.31 (graciously abbreviated to PSO J0309 + 27), was first discovered in March 2020 and is located in the constellation of Aries, about 12.8 billion light-years from Earth. The blazar is the brightest in radio waves and the second brightest in X-rays from when the Universe was less than a billion years old. It is also the most distant galaxy from us to have ever seen such a fighter jet, making it the oldest blazar ever seen.
“These properties make it an ideal object to study [active galactic nuclei] at cosmological distances, ”Spingola wrote. “We know very little about the young universe, so new information is crucial to better understand that era.”
The team found that the Blazar jet moved three-quarters of the speed of light; an extraordinary pace, though not the fastest, as other blazars have been recorded at more than 90% the speed of light.
The beautiful stripe you see is actually an image created by integrating three different observations of the jet, taken at different radio frequencies, to evoke structures of the jet that are invisible on the other. All told, the image shows a blazar beam extending up into the empty black, with the brightest part toward the bottom, where the core of the blazar lies.