active galactic nuclei (AGN)
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Active Galaxies Demystified
Active galaxies are, without a doubt, absolutely spectacular. Though rare, they tell a critical part of the story of galaxies — and of the universe as a whole. And we’ve spent the last few posts exploring them in depth. But…
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A Full Story of Galactic Evolution
Over the course of the last few posts, we’ve explored different types of active galactic nuclei: Seyfert galaxies, double-lobed radio sources, and quasars. At the heart of each of these galaxies lies a supermassive black hole, feeding off an energy…
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Why Galactic Nuclei Erupt
Astronomers know that when galaxies’ nuclei become active — releasing tremendous floods of energy — supermassive black holes are the ultimate culprit. We also know that supermassive black holes lurk at the hearts of most large galaxies. But most galaxies…
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How Supermassive Black Holes Work
We first took a peek at supermassive black holes back in our discussion of galaxies. But now that we’ve covered a few types of active galaxies, it’s time to take a deeper dive. Okay, I guess we won’t really be…
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What the Heck is a Quasar?
I’ll give you a hint: this is not an image of a quasar. This image is from a first-season Star Trek: The Original Series episode, “The Galileo Seven” — the original footage, before it was remastered (and before astronomers had…
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Exploring Radio Lobes
Meet galaxy NGC 5128, also known as Centaurus A. Anyone notice something weird going on here? If you’ve been following my recent posts on galaxies, you might notice that this does not look like a typical galaxy. It has a…
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What are Seyfert Galaxies?
Meet NGC 1566, an intermediate spiral galaxy in the constellation Fornax. To the human eye, this galaxy looks almost like any other spiral: It has a central nucleus and spiral arms, and it’s full of gas and dust. As an…
