Black Holes: physics and astronomy

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Black Holes physics and astronomy
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Black Holes in classical physics Given a mass M,
how compact (squished) does it have to be?

• Schwarzschild Radius

Rs 2GM
c2
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General Relativity and Black Holes

• General Relativity a theory of gravity
• Basic mathematical object 4 dimensional spacetime

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Basic Ingredients of General Relativity

• (A) Objects move between 2 points in spacetime on
  the shortest path between those points
  (geodesics)
• (B) The presence of mass warps or bends spacetime

The Einstein Field Equations
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General Relativistic Black Holes

• For sufficient concentration of mass in
  sufficiently small region, there is a rip or hole
  poked in spacetime

Schwarzschild Radius
DEMO with analogs
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Question Do black holes exist in nature?

• What would you look for? What kind of
  observation would reveal a black hole?

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Cygnus X-1 the prototype black hole
http//blackholes.stardate.org/directory/factsheet
.php?id13
Artistss conception of Cygnus X-1
http//blackholes.stardate.org/directory/image.php
?id13img90
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Where Cygnus X-1 is located
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An example of a black hole system

• Black hole and a red dwarf

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A key to black holes hot accretion disks
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Present knowledge about black holes

• 20 confirmed black hole systems
• Least massive 3.7 - 5.0 solar masses
• Most massive 10.0 - 18.0 solar masses
• Remember all pulsars have 1.4 solar masses

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Black holes on larger scales the center of the
Milky Way

• A black hole of 2.5 million solar masses, and
  more to come