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?"

00:02:30

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

Résumé

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.

A retenir

🌌 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.

Chronologie

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.

Carte mentale

Vidéo Q&R

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.

Voir plus de résumés vidéo

Accédez instantanément à des résumés vidéo gratuits sur YouTube grâce à l'IA !

Sous-titres

Défilement automatique:

00:00:00
in a supermassive black hole world the
00:00:03
ones that we have the most success at
00:00:05
observing are the ones that have gas
00:00:07
flowing in to grow the black hole that
00:00:10
gas that flows in gets really really
00:00:12
really hot and as it's heated up it
00:00:15
emits a lot of light and so we have the
00:00:17
opportunity to observe that light from
00:00:19
the gas that's flowing in that sits
00:00:20
outside the event horizon so when you
00:00:23
have that gas flowing in we call that
00:00:26
black hole active because it's actively
00:00:30
growing its mass that black hole
00:00:32
typically in the months that we've been
00:00:34
able to find sit in the Centers of
00:00:36
galaxies and so they are in the galactic
00:00:38
nucleus so when you take those two
00:00:40
things you put them together you have an
00:00:42
active nucleus and in general they live
00:00:46
in galaxies so it's an active galactic
00:00:48
nucleus so a GN is an active galactic
00:00:51
nucleus and all that means is that it's
00:00:53
a growing supermassive black hole that
00:00:55
sits at the heart of a massive galaxy so
00:00:59
that's the most big broad generic term
00:01:01
any black hole that is actively growing
00:01:03
and is sitting in the center of a galaxy
00:01:05
is called an active galactic nucleus
00:01:07
then you have a lot of other terminology
00:01:10
so quasar is the brightest example of an
00:01:15
active galactic nucleus so it still
00:01:17
belongs to the class of active galactic
00:01:19
nuclei or a GN but it's the really high
00:01:22
luminosity subset of those objects and
00:01:26
quasar actually comes out of some really
00:01:28
interesting historical terminology
00:01:31
originally when people found these
00:01:33
growing super massive black holes they
00:01:35
didn't know what they were they were at
00:01:37
really high distances and so we couldn't
00:01:39
see any features in their image they
00:01:42
just looked like a point source and
00:01:44
people thought well they look like stars
00:01:46
but they kind of don't look like stars
00:01:47
and so they started calling them quasi
00:01:49
stellar objects and then that morphed
00:01:52
into some other terms that are kind of
00:01:54
like qso so qso is a quasi stellar
00:01:58
object and then people started to see
00:02:02
these same objects at radio wavelengths
00:02:04
and a whole other suite of terminology
00:02:07
built up around their radio properties
00:02:08
whether they could throw out these
00:02:09
really bright jets that we some see with
00:02:12
some very luminous black holes etc etc
00:02:16
but the two basic categories are active
00:02:18
galactic nuclei that describe all
00:02:20
growing supermassive black holes and
00:02:22
quasars which are the brightest most new
00:02:24
luminous subset of those growing black
00:02:26
holes