(ORDO NEWS) — Astronomers from the University of Western Sydney have discovered one of the largest relativistic jets in the sky.
More than a million light-years long from start to finish, the jet poured out of the black hole with tremendous energy and almost at the speed of light. But in the vast expanse between galaxies, it is not always possible to achieve your goal.
A Closer Look The
galaxy NGC2663 is only 93 million light-years away. From a cosmic point of view, if our galaxy were home, NGC2663 would be one or two districts away from us.
Looking at its stellar glow through a conventional telescope, we see the familiar oval shape of a “typical” elliptical galaxy, where there are about ten times more stars than in the Milky Way.
The galaxy looked typical until NGC2663 was viewed with the ASKAP (Australian Square Kilometer Array Pathfinder) CSIRO telescope in Western Australia, a network of 36 linked radio dishes that form a single super telescope.
Radio waves helped detect a jet of matter ejected from the galaxy’s central black hole. This powerful stream of matter is about 50 times larger than the galaxy itself: if our eyes could see it in the night sky, it would be larger than the moon.
Although astronomers have found such relativistic jets before, NGC2663’s sheer size (more than a million light-years away) and relative proximity make it one of the largest known jets in the sky.
So, what did we see in the “close-up” of this jet, thanks to the accuracy and power of ASKAP?
The study is led by doctoral student Velibor Velovic of the University of Western Sydney and has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.
The Evolutionary Map of the Universe (EMU) survey shows how matter between galaxies presses on the jet from the sides.
This process is similar to the effect seen in jet engines. As the exhaust plume breaks through the atmosphere, it is pushed away from the walls by ambient pressure. This causes the jet to expand and contract, pulsing as it moves.
Bright spots, known as “Mach Disks”, can be seen in the jet. As the compression progresses, the stream glows brighter.
The largest in history
As with jet engines, Mach disks have also been seen in smaller jets. When such jets crash into dense clouds of gas, it illuminates them as they pass. But side compression of the jet is a more subtle effect that makes it difficult to see.
However, before NGC2663, we did not observe this effect on such a huge scale.
This tells us that there is enough matter in the intergalactic space around NGC2663 to push against the jet from the sides. In turn, the jet heats and densifies matter.
This is a vicious circle: intergalactic matter enters the galaxy, the galaxy forms a black hole, the black hole releases a jet, the jet slows down the flow of intergalactic matter into the galaxy.
These jets affect how gas turns into galaxies as the universe evolves. It is amazing to see such a direct illustration of this interaction.
The EMU study, which is also responsible for identifying a mysterious new type of astronomical object called the “weird radio circle”, continues to scan the sky. This wonderful jet will soon be joined by many other discoveries.
As these discoveries emerge, we begin to better understand how black holes form galaxies around them.
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