PowerPoint Presentation - Super Massive Black Holes

Download Report

Transcript PowerPoint Presentation - Super Massive Black Holes

Black Holes
Earth & Space Science
March 2015
Black Holes: A Theoretical
Definition (A Review)
An area of space-time
with a gravitational field
so intense that its
escape velocity is equal
to or exceeds the speed
of light.
Types of Black Holes
“Normal Sized” Black
Microscopic (Primordial)
Super-Massive Black
Holes (On the order of
millions to billions of Solar
Estimated 4.1 million
solar masses for Milky
Way Black Hole
(Sagittarius A)
How Normal Black Holes Come
About (A Review)
Most Black Holes are
believed to come
about from the death
of massive stars.
When a sun the size of ours dies, it
becomes a white dwarf:
Image of Sirius A and Sirius B
taken by the Hubble Space Telescope.
Sirius B, which is a white dwarf, can be
seen as a faint pinprick of light to the
lower left of the much brighter Sirius A.
Located in Canis Major, Sirius is the
brightest star in the Earth’s night sky.
The distance between A and
B varies from 8 to 31 AU.
When a sun
1.5 to 3 times
the size of ours
dies, it
becomes a
Neutron Star.
Neutron stars are the densest and smallest
stars known to exist in the universe; with a
radius of only about 7 mi, they can have a
mass of about two times that of the Sun.
Neutron stars have been observed to "pulse" radio
and x-ray emissions. Through mechanisms not yet
entirely understood, these particles produce
coherent beams of radio emission.
The pulses come at the
same rate as the rotation
of the neutron star, and
thus, appear periodic.
Neutron stars which emit
such pulses are called
A pulsar is short for pulsating radio star
First detected in 1967
When a sun 10 times the size of our sun
dies, gravity crushes it causing a supernova:
SN 1604 Latest observed
supernova in our galaxy.
Maintained naked-eye
visibility for 18 months.
SN 1987A visible to the
Naked eye for over 3 months
When a sun 100 or more times the
size of our sun dies it sets off the
biggest explosion in the universe, a
hypernova, creating a Black Hole.
SN 2006gy occurred in a distant galaxy
approximately 238 million light years away.
Therefore, due to the time
it took light from the
supernova to reach
Earth, the event
occurred about 238
million years ago.
SN 2006gy was an extremely energetic
supernova, sometimes referred to as a hypernova
or quark-nova discovered on September 18, 2006.
Brightest ever recorded supernova.
Preliminary indications are that it was an unusually
high-energy supernova of a very large star, around
150 solar masses.
Neutron stars and black holes are among the
more exotic members of the vast population of
stars throughout the universe.
These objects represent the end states of
stellar systems, yet despite their bizarre
nature they do seem to fit quite well within
our models of stellar evolution.
This stunning image is
actually a composite of
three images taken by
telescopes in Earth orbit:
optical light (yellow)
observed with Hubble,
X-ray radiation (blue and
green) with Chandra and
infrared radiation (red) with Spitzer.
The object is
Cassiopeia A,
the remnant of a
supernova that
exploded about
300 years ago:
the small turquoise
dot at the center
may be a neutron
star. (NASA)
The Smithsonian's Astrophysical
Observatory in Cambridge, MA, hosts the
Chandra X-ray Center which operates the
satellite, processes the data, and distributes
it to scientists around the world for analysis
Where Could Super-Massive Black
Holes Exist?
The only known
places in the Universe
where there could be
enough mass in one
area is in the center
of massive galaxies
Not believed to be
anywhere else
Quasars: What are They?
In some places where point sources of radio waves were
found, no visible source other than a stellar-looking
object was found (it looked like a point of light --- like a
star does). These objects were called the "qausi-stellar
radio sources", or "quasars" for short.
Later, it was found these sources could not be stars in
our galaxy, but must be very far away --- as far as any of
the distant galaxies seen. We now think these objects
are the very bright centers of some distant galaxies,
where some sort of energetic action is occurring.
Active Galactic Nuclei
In some galaxies, known
as "active galactic nuclei"
(AGN), the nucleus (or
central core) produces
more radiation than the
entire rest of the galaxy!
Quasars are very distant
The magnetic fields
around black holes that
are thought to produce
the spectacular jets of
high-energy particles
rushing away from black
holes come from the disk
of hot gas around the
black hole, not the black
hole itself.
The jets are made by the
Magnetic field of the
matter before it goes in
the Black Hole.
The Chandra X-ray image
is of the quasar PKS
1127-145, a highly
luminous source of Xrays and visible light
about 10 billion light
years from Earth. An
enormous X-ray jet
extends at least a million
light years from the quasar.
Observations of Super Massive
Black Holes
Radio observations
by various radio
X-ray observations
from the orbital
Chandra Observatory
Optical Observations
from Hubble Space
NASA's Chandra X-ray Observatory is a
telescope specially designed to detect Xray emission from very hot regions of the
Universe such as exploded stars, clusters
of galaxies, and matter around black
Because X-rays are absorbed by Earth's
atmosphere, Chandra must orbit above it,
up to an altitude of 86,500 miles in space.
Abundance of elements
How and where did all the elements form?
Were they always present in the universe, or
were they created after the universe
Since the 1950s, astronomers have come to
realize that the hydrogen and most of the
helium in the universe are primordial—
that is, these elements date from the very
earliest times.
All other elements in our universe result
from stellar nucleosynthesis—that is, they
were formed by nuclear fusion in the hearts
of stars.
Therefore, all elements heavier than helium
formed by stellar nucleosynthesis.
The End