As If you are using SpaceEngine or Not, But as a Space Enthusiast You know Almost Every Average Galaxy's Nuclei Contains At least One Supermassive Black hole Having Variety in Mass, In Characteristics, Structures and Several Aspects.

So Here We'll Focus Only its Distinctive Features and some bit of depth So that You know Its Basic Properties.


We will Categorize These Galaxies on the Basis of their Supermassive Black Holes.

The Central Bright Oval or Bar shaped Structure Called Galaxy's Nucleus Whose Stars Orbit in Planet Like Flat Plane(Spiral Galaxy) or In Every Possible Directions with Reference To an Ellipsoid Galaxy.

In these Regions, Stars are Closely Situated than outer parts of galactic regions. Sometimes It Contains Dense Molecular Clouds, So many Globular and open Clusters etc. This is a Rich Region of Stellar and Galactic Activity, However In most Cases it is faint in Elliptical Galaxies and Not Easily Visible.

We'll Discuss in the Guide Which are Important Points Of Confusion Among Space Lovers.

A Normal Galaxy Whose Central Black hole is Not Significantly Active

If a Galaxy's Nucleus is Not Remarkably Active Means It does Surrounded By Dust and Gas, Dark matter and Other Structures But Not Hold any Significance Characters Like Radio Emission and Jets Rather it has Mixture of Supernovae Old Stars, Dark matter, Large Nebulae, Interstellar Gas Dust etc. Supermassive Black Hole Doesn't Show Any Particular Activity, However It still Can Consume Dust, Stars, Black holes etc. which reach its very Near.

Our Milky Way Galaxy was Used to be an Active Galaxy in few Million Years past, Revealed By some Observations Of Its Gamma Ray and X-Ray Bubbles which are Extended up to 30,000 Light Years in Both Directions Up and Down Of its Galactic Plane. Their Supermassive Black holes are Millions times are massive than Sun.



Sagittarius A* - Milky way's Central Black Hole

An Active Galaxy : Messier 87

These Types of Galaxy's Nuclei Called AGN (Active Galactic Nucleus)

Supermassive Black Hole of these Galaxies, Collect A Large Amount of Gas and Dust, Compresses and Heat up the Gases, Form A Very Huge Accretion Disk By helping Gravity and Which Causes them To Glow Across Several Wavelength Infrared To X-Ray. It also Contains Cooler Ring of Dust and Gas Which is called Torus its Diameter is about Few Light Years. Close To black hole Some amount of Gas Also Moves Outward At nearly speed of light. Its Luminosity Varies By our Viewing Angle If These Jets Are Shooting To our Earth It'll Appear More Bright and Variable.



M 87 Supermassive Black Hole Vs Other Stars



An AGN's Black Hole



There are Mainly Two Types of Active Galaxies which are Radio Quiet or Loud AGNs which Indicates How Strong or Weak Radio wavelength They Emit , But Others are also Proposed Which Falls at least in those Two Categories.


These Are Basically Radio Loud Galaxies, Its AGN Creates a Bubble or Large Nebula like Structure called Lobe in their Host Galaxy Which Can Expand Several Light Years. For More Information You can Google The Hercules A Galaxy. This is Classified According to a Scheme Called Fanaroff-Riley Classification on How Bright Appear Those Radio Emission's Lobes As the Distance.

Remember : These Galactic Jets Are Not Considered as Galaxy's Parts Nor It is used to Measure Its Radius, Diameter, Surface Brightness etc.

a) FR - I

Its Jets Are More Diffused, Elongated and Low Brightness. Their Radio Lobes or Structures Lose their Brightness as The Distance Increases.

b) FR - II

It is The Most common type Radio Galaxy, its Jet often Create a Large and Bright Ellipsoidal Nebulous Structures on galaxy's Either Side.

Although There is Another Class Called Giant Radio Galaxy (GRG) Which are Just Larger Versions of Mentioned Above. Their Radio Emissions Can Reach Several Mega parsecs.

For Example. Alcyoneus Galaxy is an FR - II GRG whose Radio Lobes Are Extended almost 16 Million Light Years or 5 Mega parsec and 3C 236's Lobes are Expanded about 15 Million Light Years. Their Radio Emissions are Many Times Larger Than Its own Galaxy.



These Radio Quiet Galaxies are like Small Quasars Because They have a Very Bright Core. Their Host Galaxies are Clearly detectable and They Look like Normal Spiral Galaxies Though Their Radio Spectral Features make them Different.



These are Often Found in Elliptical Galaxies but rarely in Spirals, also They are Much Brighter Stronger Version of Seyfarts. They also Have Their Loud and Quiet Radio Variants. It is Basically a Nucleus of a galaxy which emits Extremely Luminous Electromagnetic Radiations That's Why It's Host Galaxies are Not Clearly Detectable. It Tremendous Power Comes from Ultra Giant Supermassive Black hole. They Are More Similar To Stars Rather than a Galactic Nuclei.

So all those Structures Are Created By Their Active Supermassive Black Holes But Our Supermassive Black hole (SMBH) is a Relatively Silent in some Respects. further You can Read Them in more Detail.

This Class is named After An American Scientist Carl Keenan Seyfart

These Active Galaxies Are Most Common, They Look like Normal Galaxies But Their Secret Reveals in Their Spectral Studies. Seyfart Class Galaxy Emit Their Radiation in Infrared at large amount, some also Radiate X-rays. Its Core's Brightness is Equal to All Brightness of Stars in Milky Way.

It is Divided in Two Sub classes :


These Galaxies Show Unusual Features in Visible Light, Their Accretion Disk Vicinity is in High Turbulence. It Moves at Very High speed.


These Are Just Opposite of Type I Class Which Bear Those Characteristics in Less. Also Their Accretion Disk is Relatively Quiet or in slower motion.

This is much Similar to Quasars which Are Second Type of AGNs. Unlike Quasars Its Host Galaxies Are Clearly Detectable.

Word Quasar is a Somehow Contraction of "Quasi-Stellar Radio Source". Sometimes It is Called QSO (Quasi-Stellar Object)

These Are one of the Most Powerful Objects in universe, It Can Emit Much more Energy Than A whole Milky way like Galaxies do. They are Extremely Luminous and Energetic Nuclei which is Powered By Supermassive Black holes (SMBH) Massive Than Several Billion Times That of sun. There Are almost 1 Million Quasars Are Discovered. Quasars Are Much more Brighter than Its Host Galaxy. This makes them Different Than Other AGNs.

There is Another Variant of Quasars other than Radio Loud and Quiet Types :


This Quasar Shoots Jets Approximately Direction of Earth and There is almost 2700 Known Blazars.

After Reading Above Sections, Here is The Brief and Easily Understandable Summary in Below's Image. In this image Has been Tried to Get rid of Common Confusing Objects Among Galaxies, AGN, Quasar, Blazar.

Just keep in mind The Two Red Words are Name of Classes, However The M87 Galaxy Does have Strong Radio Emission Nevertheless its not a Quasar According To Studies.