Black Holes. • Regions of space from which nothing, not even light, can escape because gravity is so strong. • First postulated in 1783 by John Michell • Term “black hole” coined in 1969 • Observational evidence starting in 1970s. We see the effects a black hole has on matter and radiation
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• Regions of space from which nothing, not even light,
can escape because gravity is so strong.
• First postulated in 1783 by John Michell
• Term “black hole” coined in 1969
• Observational evidence starting in 1970s
We see the effects a
black hole has on matter and radiation
near it; we have not yet seen
a black hole directly.
• Diagram of the effect of gravity
(gravitational potential well)
near the black hole on the fabric
• It is a 2-D depiction of a 3-D
Jets of fast moving particles
Disk of galaxy with
supermassive blackhole in center
Halo of gas, and dust
Quasars, Blazars, Seyferts, AGN, ….etc, etc, etc
(The Short, Short Story…)
• Black holes
• Active Galaxies
• Gamma-ray bursts
• Diffuse emission
Merging Neutron Stars
HETE II (launched 7 October 2000)
Our gamma-ray detector measures 5.27 x 10 -6 ergs/cm2
What’s so impressive about that?!??!!!
What was emitted
What you detect =
4 p D
v = Ho * d
Ho is called the Hubble constant. It is generally
believed to be around 65 km/sec/Mpc.
This is an optical spectrum of a GRB from Keck, the
world’s largest optical telescope. The locations of
several Doppler shifted spectral lines are shown.
Step-by-step power calculation:
1. Measure the redshift of three spectral lines
2. Take the average redshift, z
3. From this, calculate the velocity v=z*c
4. Using the Hubble Constant, get the distance
5. Convert distance in Mpc to distance in cm
6. Now, with the distance to the GRB, and the
value measured at our detector, calculate
power: P=4πd2*measured flux
1 Mpc ~ 3 x 10 19 km
L = 5.3 x 10-6 ergs/cm2
are the most
in the Universe!