Black Holes

1. & Neutron Stars Black Holes

2. Los reviewos • Binary star- Two stars that orbit around a common center of mass. • White Dwarf- A star that has exhausted most of its nuclear fuel and has diminished in size. Has no atmosphere. • Solar Masses- A unit of mass equivalent to the mass of the Sun. • Neutron Star- The imploded core of a massive star produced by a supernova explosion.

3. Types of Supernovae Type 1a • Type 1a: This type of supernova results in binary star systems. This comes about when a white dwarf absorbs mass from a companion. So much mass piles up on the white dwarf that its core reaches critical density. This results in an uncontrolled fusion of carbon and oxygen, and the star detonates! • Type 2: These supernovae occur at the end of a massive star’s lifetime, when its nuclear fuel has been exhausted. Therefore, the star is no longer supported by the release of nuclear energy. If the star’s core is massive enough, it will collapse and become a supernova. http://geoweb.princeton.edu/students/courses/206/Slide1.gif Type 2 http://www.pnl.gov/energyscience/01-02/11-questions/supernova.jpg

4. Where does the Core go? • When the core is lighter than 5 solar masses, it is believed that the neutrons are successfully halting the star’s collapse, causing a neutron star. • When a core does collapse, the central core becomes so dense, that something would have to travel faster than the speed of light to escape! • This strong pull of gravity creates a black hole from the core of the original star. A Black Hole

5. What the heck are neutron stars? • Neutron stars are dense balls of neutrons that remain at the core of a star after a supernova explosion has destroyed the rest of the star. • Typical neutron stars are about 20 km wide big as Manhattan and contains more mass than the sun. muy dense!

6. PULSARS • A pulsar is a rapidly rotating highly magnetized neutron star, formed in the supernova of a massive star. • These charged particles flow along magnetic field lines, producing radiation that beams outward as the star spins on its axis. • Last about 100- 1,000 years.

7. Neutron stars and black holes are among the most exotic objects in the universe.A lump of neutron star matter the size of a sugar cube would weigh as much as all humanity, and the stars have magnetic fields a trillion times Earth's. . Recently the Rossi Explorer, a new X-ray satellite, discovered a remarkable new phenomenon of neutron stars that strip matter from their companion stars: their brightness varies almost periodically more than a thousand times per second.

8. Pulsars are like lighthouses because when the pulsar rotates the beams of light and radiation stretch across great distances at set timed intervals.

9. “Glitches“- small increases in a neutron star’s spin rate.

10. This is the youngest known pulsar and lies in the center of the Crab Nebula, the supernova remnant of its birth explosion, which was witnessed by Europeans and the Chinese in the year 1054 A.D. as a daytime light in the sky. The pulsar rotates about 30 times per second and it sounds like…

11. H E L P M E L B A C K A O hole T N I’M FALLING I

12. Who, What & Where • Black Holes trap everything they consume. • Light is no exception. • Hence the name. • So……….how can they be detected? • Two ways: A star rapidly orbiting around “nothing”. • X-Ray evidence of an accretion disk from a neighboring star.

13. Properties of black holes • A black hole is a region of space so densely packed with matter that nothing, not even light, can escape. • They have: Infinite density & zero volume. • Outside Horizon • Boring far away, Large tidal forces, Time slows down • Inside Horizon • Everything moves toward the center, Time and space interchange roles.

14. What is meant by escape velocity? • The minimum speed at which an object can move away from a source of a gravitational field. • Escape velocity is proportional to the square root of the mass divided by the square root of it radius. • If you have infinite mass and zero volume the escape velocity exceeds c. • See 22.5 in that black thing made of paper

15. E=mc…..squared • Just before matter is gobbled up by a hungry black hole, it's hurtling around the monster at nearly the speed of light. This heats up the material and it can release a tremendous amount of energy as X-rays. Different elements release energy with a specific fingerprint that astronomers can detect.

16. Evidence of Black Holes in Binary Systems • Just as with neutron stars, if a black hole is in a binary and it strips gas from its companion, we can detect X-rays from the resulting accretion disk. The light from accretion disks around a black hole looks very similar to the light from disks around neutron stars.

18. Why Cygnus? • Astronomers have a candidate for a black hole in the constellation Cygnus x-1 (X-ray source) • Discovered in the early 1970s • The X-ray emitting region is likely an accretion disk formed as matter drawn from the visible star is spiraled down onto the unseen component. • As the gas flows towards the black hole, it becomes superheated and emits the X-rays just before they are trapped forever below the event horizon.

19. Black Hole in the Constellation CYGNUS • Schematic of Cygnus

22. Schematic of an x-ray binary system viewed edge on. The orbital period of both objects can be easily determined as one body passes in front of the other.

23. Black holes are NOT cosmic vacuum cleaners—they will not consume everything! • One you step inside the event horizon, you are trapped there forever. • A human would be stretched apart if they went any closer this is known as spaghettification.

24. Last slide! Tales of a rogue monster…………..

26. Supermassive Black holes • Not ready 2 b cene

27. Evidence of Black Holes in the Centers of Galaxies • In the centers of galaxies, astronomers have found that stars and gas are moving extremely fast, orbiting some very massive, unseen object. • You can also understand the presence of a black hole in the center of some galaxies. This is done by observing stars near the center of the galaxy. If the stars are moving very rapidly around some unseen object, Kepler's laws can be used to estimate the mass in the center. In some cases the mass must be at least a hundred million times our Sun's mass, in a region only a few light years across. Astronomers are virtually certain that the only explanation is a black hole, but we lack the direct evidence. • Masses range from millions to billions of times greater than the sun. • Intense energy emission from the centers of these galaxies, and short-timescale fluctuations in that emission, suggest the presence of compact, massive objects. • Supermassive black holes are believed to exist at the center of most galaxies. There is evidence that our own galaxy, the Milky Way, harbors a 2.5 million solar mass black hole at its heart.

28. Super Massive Black Holes(SMBH)

30. Gravitational red-shift & time dialation Any clockwise rotation to the hole would appear to tick more slowly than an equivalent clock on board the spacecraft.

31. What is Singularity? • Singularity is a point in the universe where the density of matter and the gravitational field are infinite.

32. The Laws of Quantum Gravity must be understood to explain a black hole and singularity. • 2 Theories of Relativity: • The Special Theory of Relativity • Proposed by Einstein in 1905 • The general Relativity • What results when gravity is included in the framework of special relatiity.

33. Event horizon and Schwarzschild radius • The Schwarzschild radius is the radius at which the outermost boundaries of the black hole would start. • The event horizon of a black hole can only increase, not decrease.

34. The photon sphere • A ball of photons orbiting a black hole as a result of the gravity pulling in the photons.

35. STELLAR TRANSITS -To detect a black hole, we would have to observe it passing in front (transiting) of a star. -What happens is the starlight would be deflected when it passes the black hole on the way to earth. It’s almost like a solar eclipse, where there is a bending of starlight around the edge of the sun. Gravitational Light Deflection -The bend of the light around a black hole makes it almost impossible to observe. -The black hole is superimposed against the bright background of its star companion.

36. Gravity Waves • Gravity waves are ripples in the curvature of space-time continuum created by the movement of matter. • They move across the space-time continuum. This is the enmeshed combination of our 3 perceived physical dimensions + time. Thus the 4th dimension.

37. Gravity waves were first hypothesized by in Albert Einstein's general theory of relativity, which predicted that an accelerating mass would radiate gravitational waves as it lost energy. Example: It would be expected that 2 pulsars in orbit around each other should emanate gravity waves as their orbits decay.

38. Some suspitions • LMCX-3 • AO620-00 • …and a half dowzen other known objects in or near our galaxy that may turn out to be black holes…(However, Cygnus, LMCX-3, and AO620-00 are the strongest claims)

40. Glossary • Accretion disk: • the pattern of flow of matter from a normal star to a neutron star or black hole, which is flattened and thus disk-like. • Degeneracy pressure: • a quantum-mechanical phenomenon; fermions, such as electrons or neutrons, obey Pauli's exclusion principle, so that no two fermions can occupy the same state. Thus, if fermions are squeezed together they resist even if there is no temperature and no energy generation. This resistance to squeezing is degeneracy pressure. • Equation of state: • the relation between the pressure and density of a given type of matter, which is an indication of how the matter resists squeezing. If the matter resists squeezing strongly (e.g., water), the equation of state is stiff; if it resists squeezing only weakly (e.g., air), the equation of state is soft. • Event horizon: • in a black hole, the point beyond which events cannot be detected. This is the point of no return; an object that falls inside the event horizon can't get out. • Kepler's laws: • rules for the orbital motion of planets or anything else bound by gravity. The law of most interest here is that the square of the orbital period is proportional to the cube of the orbital separation, and inversely proportional to the mass. Thus, if we see an orbital period, we can estimate the mass or orbital separation and therefore constrain the mass and radius of a neutron star. • Singularity: • in a black hole, the "center point", at which densities, tidal forces, and other physical quantities become infinite. Our current physical theories break down at this point. • Tidal force: • the force an object feels because of the differential pull of gravity at different distances.