What is an active galactic nucleus (AGN)?

An AGN is a growing supermassive black hole located at the center of a galaxy, actively consuming gas, and emitting light.

What is the relationship between quasars and AGNs?

Quasars are the brightest and most luminous subset of active galactic nuclei (AGNs).

How can we observe supermassive black holes?

By observing the light emitted by the gas that flows into the black hole and gets extremely hot outside the event horizon.

What happens when gas flows into a black hole?

The gas gets very hot as it approaches the event horizon, emitting a lot of light, indicating an active galactic nucleus.

What does QSO stand for?

QSO stands for quasi-stellar object, a term used historically when quasars were first discovered.

Astro101 - "What is the difference between an active galactic nucleus and a quasar?"

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https://www.youtube.com/watch?v=gFjUpGAW-7w

Ringkasan

TLDRThis passage explains the concept of supermassive black holes, particularly those designated as active galactic nuclei (AGN). These are black holes actively growing by consuming gas, causing them to emit substantial amounts of light, allowing astronomers to observe them. AGNs typically reside in the centers of galaxies, in their galactic nuclei. Quasars represent the brightest subset of AGNs, initially detected as quasi-stellar objects (QSO) due to their starlike appearance but significant differences, particularly at great distances. The passage also touches on the historical terminology and radio wavelength observations that helped classify these phenomena.

Takeaways

🌌 Active Galactic Nucleus: Describes growing black holes in galaxy centers.
🔭 Observation: Done through the light emitted by infalling gas.
📚 Quasars: Brightest subset of active galactic nuclei.
⚡ Energy Emission: Result of gas heating up as it nears the black hole.
🌟 Historical Term: Quasars were once called quasi-stellar objects.
🔍 QSO: An early term for quasars due to their star-like appearance.
📡 Radio Observations: Added to understanding of black holes and AGNs.
💡 Active Growth: Signified by constant gas flow into black holes.
🌀 Galactic Nucleus: Central region where AGNs reside in galaxies.
✨ High Luminosity: Key feature of quasars compared to other AGNs.

Garis waktu

00:00:00 - 00:02:30
An active galactic nucleus (AGN) is an actively growing supermassive black hole located at the center of a galaxy, and these can be observed by the light emitted from the gas flowing into it, which gets extremely hot. This makes the black hole active, as it grows by accumulating mass from the gas. The term AGN refers broadly to any such black hole, while a quasar is a highly luminous example of an AGN. Originally, these bright objects were identified as quasi-stellar objects (QSO) due to their star-like appearance at high distances. Over time, terminology evolved to describe various properties, including radio wave emissions and bright jets, associated with these luminous black holes.

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Video Tanya Jawab

What is an active galactic nucleus (AGN)?
An AGN is a growing supermassive black hole located at the center of a galaxy, actively consuming gas, and emitting light.
What is the relationship between quasars and AGNs?
Quasars are the brightest and most luminous subset of active galactic nuclei (AGNs).
How can we observe supermassive black holes?
By observing the light emitted by the gas that flows into the black hole and gets extremely hot outside the event horizon.
What happens when gas flows into a black hole?
The gas gets very hot as it approaches the event horizon, emitting a lot of light, indicating an active galactic nucleus.
What does QSO stand for?
QSO stands for quasi-stellar object, a term used historically when quasars were first discovered.

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Gulir Otomatis:

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in a supermassive black hole world the
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ones that we have the most success at
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observing are the ones that have gas
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flowing in to grow the black hole that
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gas that flows in gets really really
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really hot and as it's heated up it
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emits a lot of light and so we have the
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opportunity to observe that light from
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the gas that's flowing in that sits
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outside the event horizon so when you
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have that gas flowing in we call that
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black hole active because it's actively
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growing its mass that black hole
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typically in the months that we've been
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able to find sit in the Centers of
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galaxies and so they are in the galactic
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nucleus so when you take those two
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things you put them together you have an
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active nucleus and in general they live
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in galaxies so it's an active galactic
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nucleus so a GN is an active galactic
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nucleus and all that means is that it's
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a growing supermassive black hole that
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sits at the heart of a massive galaxy so
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that's the most big broad generic term
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any black hole that is actively growing
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and is sitting in the center of a galaxy
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is called an active galactic nucleus
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then you have a lot of other terminology
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so quasar is the brightest example of an
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active galactic nucleus so it still
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belongs to the class of active galactic
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nuclei or a GN but it's the really high
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luminosity subset of those objects and
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quasar actually comes out of some really
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interesting historical terminology
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originally when people found these
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growing super massive black holes they
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didn't know what they were they were at
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really high distances and so we couldn't
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see any features in their image they
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just looked like a point source and
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people thought well they look like stars
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but they kind of don't look like stars
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and so they started calling them quasi
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stellar objects and then that morphed
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into some other terms that are kind of
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like qso so qso is a quasi stellar
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object and then people started to see
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these same objects at radio wavelengths
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and a whole other suite of terminology
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built up around their radio properties
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whether they could throw out these
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really bright jets that we some see with
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some very luminous black holes etc etc
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but the two basic categories are active
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galactic nuclei that describe all
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growing supermassive black holes and
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quasars which are the brightest most new
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luminous subset of those growing black
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holes