quasar

Active Galaxies Demystified

/ Emma / 4 Comments

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 I know they can also be a bit perplexing. These are some of the most powerful and violent objects in the universe; it comes with the territory!

So, let’s boil this down to the basics and tie it all together. And let’s try not to get caught in a supermassive black hole in the process 😉

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Why Galactic Nuclei Erupt

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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 are not active; only a small percentage are. Our home galaxy is host to a supermassive black hole, but it’s not active. Neither is the black hole within the nucleus of our nearest galactic neighbor, Andromeda.

So, what makes a supermassive black hole erupt?

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How Supermassive Black Holes Work

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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 diving into a black hole…sorry to disappoint!

(Honestly, though, you really wouldn’t want to. It would be very uncomfortable, to say the least…and, of course, it’s a one-way trip.)

Supermassive holes are thought to lie at the hearts of most galaxies, including our own. They seem to be key to galactic structure. Most of them–including our own–are quiet. But a few percent of the galaxies in the universe emit titanic amounts of energy from their nuclei, and supermassive black holes are the ultimate culprit.

But how?

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What the Heck is a Quasar?

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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 clear images of actual quasars).

According to the story, the crew of the USS Enterprise had standing orders to investigate any quasar they came across. A landing party spent the episode struggling to survive after they crashed on a primitive planetary body within a strange nebulosity that they called a “quasar.”

At times like these, Star Trek provides a fun glimpse into the past. TOS aired in the 1960s, just as very strange “quasi-stellar objects” were being discovered. Dubbed “quasars” for short, they were a new frontier of research and discovery.

The remastered footage uses an actual (if substantially edited) image of a quasar. But the “quasar” portrayed in the story…well…yeah, not even close.

So…what are quasars, really?

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