The Milky Way is a giant among galaxies – a hundred thousand light-years in diameter. But a few galaxies make the Milky Way look like a mere bauble by comparison. They span millions of light-years – puffed up by the action of supermassive black holes.
These monsters are known as giant radio galaxies. Not only are they large, but they produce enormous amounts of radio waves.
The black hole in such a galaxy’s heart is encircled by a massive disk. As material in the disk spirals into the black hole, magnetic fields fire “jets” of some of its particles like water from a firehose. These jets can streak far into space. They end as they plow into the material between galaxies, forming “lobes” that are bright sources of radio waves.
A recent study found 15 of these giants. They’re in the constellation Sculptor, which creeps low across the south on October evenings.
The largest of them spans more than 12 million light-years. The galaxy itself is wider and heavier than the Milky Way. But the jets puff up its overall size.
It actually has two sets of jets – one nested inside the other. The longer set is older – powered up by the black hole millions of years ago. But the black hole might have slowed down its eating for a while, shutting off that flow of particles. Later, it started chowing down again, powering the second set of jets, which continue to expand – sustaining this galactic monster.
Script by Damond Benningfield

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