SUPERMASSIVE BLACK

HOLES

SRJC, Spring 2014-PHYS43

Thea Dumont

Kyle Cubba

They are a class of black holes

They are formidably larger than regular black holes

They are gigantic (100,000 X -- 1,000,000,000 X SOLAR MASS)

They are a source of quasars

They live in the center of galaxies

WHAT ARE THEY?

WOAH. THATS A LOT OF MASS!

but how big are they? _

For their mass, they’re Schwarzschild

radius (event horizon) is rather big.

Dividing the mass by the volume

defined by the Schwarzschild radius,

the density of most supermassive black

holes is less than that of water!

Schwarzschild radius is the radius at which light itself cannot escape

from the gravitational pull of the black hole. The surface this covers in

three dimensional space surrounding a black hole is known as its event

horizon.

The true density of any black hole is unknown, since it is impossible to

visually see what happens beyond the event horizon.

General relativity describes that there is a gravitational singularity at the

center of the black hole.

But then again, general relativity says a lot of things that no one seems

to know why.

Hippies say that they are wormholes to extradimensional universes.

black holes bend space-time

A normal star only curves space-time by a small amount;

But a black hole bends it to an asymptote.

Black Holes & Light Bending

Since black holes bend space-time, light

bends around black holes

Photon sphere

note the light

bending

occurring here

supermassive black hole

at the center of active galactic

nucleus

More examples of light bending

The “Einstein

Ring”

Proposed by

Albert Einstein

when coming

up with general

relativity.

Happens when a

bright object is

directly behind

massive object.

SUPERMASSIVE BLACK HOLES

& GALAXY FORMATION

Supermassive black holes are found in active galactic nuclei (AGN).

AGN is a compact center which emits high

intensity light of many wavelengths ranging

from radio to x-ray.

Quasars are a class of AGN species;

quasars have supermassive black holes at

their center and are surrounded by accretion

disks, relativistic jets spew from one or

either poles orthogonal to the disk plane.

Active galactic

nucleus

(AGN)

Ejected matter

The rotating speed of supermassive black holes and the rotating speed of

the AGN are the same. This leads to the mature formation of galactic

centers in host galaxies to supermassive black holes.

The presence of a supermassive black hole influences the galaxy to take

on a spheroidal shape (elliptical and spiral galaxies), as well as

condenses the galaxy. Influences galaxies to merge creating a spiral.

Galactic halo formation could also be explained by the presence of supermassive black holes.

The supermassive black hole in the sombrero galaxy (shown above) is measured to be1 billion times the mass of the sun, making it one of the largest known black holes!

How do we know this?

Black holes eject charged

particles in jets as they

accrete which we can spot.

When we inspect the nucleus of

galaxies, such as m87, and

there are these jets, this

implies there could be a

supermassive black hole

there.

Stars in the AGN seem to be

orbiting some unseen

massive object, this could

inferred to be a supermassive

black hole.

More material

being ejected

from a galactic

center. Notice

the accretion

disk around the

center.

Supermassive Black Holes & Light

Emission

Supermassive black holes can be found because of the large amount of

strong radio waves they emit because of the matter heating up in the

accretion

disk.

As the matter enters the black hole,

x-rays are produced; another way

researchers have to detect

supermassive black holes.

Sagittarius A* in the Milky Way

There is a supermassive

black hole in the central

bulge of the Milky Way,

located it the Sagittarius

constellation.

The supermassive black hole

is called Sagittarius A* or

Sgr A*

SGR A*

- is 40 million times more massive than our own sun

- has a radius of 6.7 light hours

- was first discovered in 1973 because of its large

amount of radio emissions

- is orbited by multiple star systems

Stars in orbit of

Sagittarius A*

Hurdling G2 Dust Cloud into

Supermassive black hole at Galactic

Center A dust cloud around 3

times the mass of the

earth is hurdling at

extremely high velocities

towards Sgr A*

Dust-Cloud Ripped Apart by Milky Way’s SMBH

What would it be like to

fall in one?

Most likely very unpleasant.

Risky: one wrong move

and you plunge into the

heart of a black hole

You’re probably cool

Done for: energy input is

required to keep you

from falling in

No escape: be prepared to

fall into an infinite abyss

You collapse into nothing

Spagettification

In a normal black hole, tidal

forces are strong and cause

elongation (spagettification)

because of the difference in

gravitational potential between

your feet and your head

Visualizing the Gravitational Vector Field

oh no!

The bright side:

at least you look trim

In a supermassive black hole, however, the tidal forces

are weaker since gravitational pull falls off at an inverse

square; you would be within the event horizon before

being pulled apart.

You never see the singularity, as the light falls into it and

never comes out.

BYE-BYE UNIVERSE

And

hello

Void!

The light

pouring in

from the

universe

collapses

into one

bright point

as you fall

into the

singularity

and are

obliterated

from history,

forever.

PURELY THEORETICALNO BASIS IN REALITY

end

Work Cited

1. Philip F. Hopkins et al. 2006 , “A Unified, Merger-driven Model of the Origin of Starbursts, Quasars, the Cosmic X-Ray Background,

Supermassive Black Holes, and Galaxy Spheroids,” Philip F. Hopkins et al. 2006 ApJS 163 1. Web, accessed 12 May 2014.

1. Marta Volonteri et al. (2003), “The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy

Formation.” ApJ, 583-599. Web, accessed 12 May 2014.

1. Haehnelt, M. G. and Kauffmann, G. (2000), “The correlation between black hole mass and bulge velocity dispersion in hierarchical

galaxy formation models.” Monthly Notices of Royal Astronomical Society. 318: L35-L38. Web, accessed 12 May 2014.

1. Jarrett L.Johnson et al. (2013), “Supermassive Seeds for Supermassive Black Holes.” The Astrophysical Journal, 771. Web, accessed

12 May 2014.

5. Ander Hamilton. http://jila.colorado.edu/~ajsh/insidebh/ Journey to the Schwarzschild Black Hole, 2014.Web, accessed 12 May14

6. http://csep10.phys.utk.edu/astr162/lect/active/smblack.html