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Neutron stars and beyond

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Presentation on theme: "Neutron stars and beyond"— Presentation transcript:

1 Neutron stars and beyond
There it is! Cassiopeia A…the remnant of the supernova of 1680

2 How many pulsars (neutron stars) are there in the sky?

3 Neutron stars: from exotica to numerous astronomical objects

4 A final mystery…pulsar masses are nearly all AT the Chandrasekhar Limit

5 Neutron Stars – Extreme Objects
Does it get any weirder?

6 Basic physics suggests a way: the maximum mass of a neutron star
What happens Here?

7 Black Holes in Theory: you check in, but you don’t check out
Theoretical ways of describing them (A) Classical physics: an object with escape speed greater than the speed of light (> c) (B) General Relativity and Black Holes

8 Black Holes in classical physics: Given a mass M, how compact (squished) does it have to be?
Schwarzschild Radius Rs = 2GM c2

9 Cramming something inside the Scharzschild Radius extreme matter
Example: Planet Earth M= 5.97E+24 kilograms Rs = 9E-03 meters = 0.9cm !!!! DEMO But always ask: do they exist?

10 General Relativity and Black Holes
General Relativity: a theory of gravity Basic mathematical object: 4 dimensional spacetime

11 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

12 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

13 But do they exist? Is nature capable of producing such strange objects?
Question: what kind of astronomical objects, with what kind of quantitative properties, would you look for?

14 They do exist, in two types
Little Ones……and……

15 ……Big Ones


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