neutron stars and beyond
DESCRIPTION
Neutron stars and beyond. There it is!. Cassiopeia A…the remnant of the supernova of 1680. How many pulsars (neutron stars) are there in the sky?. http://www.atnf.csiro.au/research/pulsar/psrcat. Neutron stars: from exotica to numerous astronomical objects. - PowerPoint PPT PresentationTRANSCRIPT
Neutron stars and beyond
There it is!
Cassiopeia A…the remnant of the supernova of 1680
How many pulsars (neutron stars) are there in the sky?
http://www.atnf.csiro.au/research/pulsar/psrcat
Neutron stars: from exotica to numerous astronomical objects
A final mystery…pulsar
masses are nearly all AT the Chandrasekhar
Limit
Neutron Stars – Extreme Objects
Does it get any weirder?
Basic physics suggests a way: the maximum mass of a neutron star
What happensHere?
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
Black Holes in classical physics: Given a mass M, how compact (squished) does it
have to be?
Schwarzschild Radius
Rs = 2GMc2
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?
General Relativity and Black Holes
General Relativity: a theory of gravity
Basic mathematical object: 4 dimensional spacetime
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
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
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?
They do exist, in two types
Little Ones……and……
……Big Ones