1. February 25, 2003Lynn Cominsky - Cosmology A3501 Professor Lynn Cominsky Department of Physics and Astronomy Offices: Darwin 329A and NASA EPO (707) 664-2655 Best way to reach me: lynnc@charmian.sonoma.edu Astronomy 350 Cosmology

2. February 25, 2003Lynn Cominsky - Cosmology A3502 Black Holes and Cosmology  BH are a possible endpoint of stellar evolution (from very massive stars)  BH warp space and time around them, thereby affecting the evolution of the galaxies  Central BH in galaxies may be the seeds that formed the galaxies and may be the only things left in the galaxies at the end of time  Central BH in galaxies are signposts that help us find the earliest galaxies

3. February 25, 2003Lynn Cominsky - Cosmology A3503 White Dwarfs, Neutron Stars and Black Holes  White dwarfs are the size of the Earth and about 1 M o  Neutron stars are 10 km in radius and about 1.4 M o  One teaspoon of NS material weighs 100 million tons!  After supernova, if cores are larger than 3 M o, a black hole will be formed

4. February 25, 2003Lynn Cominsky - Cosmology A3504 Masses of Black Holes  Primordial – can be any size, including very small (If <10 14 g, they would still exist)  “Stellar mass” black holes – must be at least 3 M o (~10 34 g) – many examples are known  Intermediate black holes – range from 100 to 1000 M o - located in normal galaxies – many seen  Massive black holes – about 10 6 M o – such as in the center of the Milky Way – many seen  Supermassive black holes – about 10 9-10 M o - located in Active Galactic Nuclei, often accompanied by jets – many seen

5. February 25, 2003Lynn Cominsky - Cosmology A3505 Black Hole Structure  Schwarzschild radius defines the event horizon  R sch = 2GM/c 2  Not even light can escape, once it has crossed the event horizon  Cosmic censorship prevails (you cannot see inside the event horizon) Schwarzschild BH

6. February 25, 2003Lynn Cominsky - Cosmology A3506 The First Black Hole  Cygnus X-1 binary system  Most likely mass is 16 (+/- 5) M o  Mass determined by Doppler shift measurements of optical lines

7. February 25, 2003Lynn Cominsky - Cosmology A3507 Journey to a black hole  This video is slightly out of date – new NASA missions are now being considered instead of ARISE

8. February 25, 2003Lynn Cominsky - Cosmology A3508 Binary star systems  Often stars are formed in binary systems  Since they have unequal masses, the more massive star will evolve faster - and reach the end of its main sequence lifetime  In some cases, the supernova of the primary star will not disrupt the binary system and a COMPACT BINARY is formed  Mass transfer can then occur from the main sequence star onto the collapsed, compact companion star - which can be a WHITE DWARF, NEUTRON STAR or BLACK HOLE

9. February 25, 2003Lynn Cominsky - Cosmology A3509 X-ray Binary movie

10. February 25, 2003Lynn Cominsky - Cosmology A35010 Measuring Mass  At least 6 stellar mass BH exist in our galaxy  Easiest to measure Doppler shift accurately when X-rays are not heating the accretion disk  X-ray “novae”

11. February 25, 2003Lynn Cominsky - Cosmology A35011 Rossi X-ray Timing Explorer  Launched in 1995 – still operational  Large area X-ray detectors to study timing details of material falling into black holes or onto the surfaces of neutron stars

12. February 25, 2003Lynn Cominsky - Cosmology A35012 “Old Faithful” Black Hole  Binary black hole system known as “microquasar”  Regular X-ray outbursts discovered with RXTE  Outbursts are linked to appearance of IR jets movie

13. February 25, 2003Lynn Cominsky - Cosmology A35013 Milky Way’s Black Hole  Best evidence comes from infrared measurements of stellar motion in central Milky Way by Ghez et al. and Genzel et al.  S2, the closest star to Sgr A* (the radio source at the exact center of the Milky Way) indicates a mass of 2.6 million +/- 0.2 M o  S2 is at a distance of 17 light- hours from Sgr A* - whose event horizon is 26 light seconds movie

14. February 25, 2003Lynn Cominsky - Cosmology A35014 NGC 4261 – best HST photo  100 million light years away  1.2 billion M o black hole in a region the size of our Solar System  Mass of disk is 100,000 M o  Disk is 800 light years across

15. February 25, 2003Lynn Cominsky - Cosmology A35015 Chandra X-ray Observatory  Launched on July 23, 1999, it is the “Hubble” of X-ray astronomy – best images ever!  Named after Subrahmanyan Chandrasekhar - Nobel prize winner who worked out the upper mass limit for white dwarfs (among many other things)

16. February 25, 2003Lynn Cominsky - Cosmology A35016 Deep Image Chandra finds black holes are everywhere! Black holes in quasars QSO Galaxy Empty Black holes in“normal” galaxies Black holes in empty space Chandra deep field

17. February 25, 2003Lynn Cominsky - Cosmology A35017 Albert Einstein  “I want to know God's thoughts...the rest are details.”  “Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.”  “With fame I become more and more stupid, which of course is a very common phenomenon.” “ God does not play dice with the Universe”

18. February 25, 2003Lynn Cominsky - Cosmology A35018 Einstein and Relativity  1905 – Theory of Special Relativity Applies to objects at a constant velocity Time dilation and length contraction Space and time are intertwined Matter and energy are equivalent  1916 – Theory of General Relativity Applies to objects that are accelerated Describes the effects of gravity on spacetime

19. February 25, 2003Lynn Cominsky - Cosmology A35019 Einstein’s equation G ab = 8  G T ab c 2 where G ab describes the geometry of spacetime and T ab describes the flow of energy and momentum through spacetime “Matter tells spacetime how to curve and spacetime tells matter how to move” -- J. A. Wheeler

20. February 25, 2003Lynn Cominsky - Cosmology A35020 Solutions to GR equations  Non-rotating, spherical black hole (Schwarzschild)  Rotating, axisymmetric BH (Kerr)  Wormholes

21. February 25, 2003Lynn Cominsky - Cosmology A35021 Andrew Hamilton’s BH Simulator  Black hole (Schwarzschild geometry) with a simplistic accretion disk, seen through a telescope. The disk, actually a ring, is at the innermost stable circular orbit, colored according to the redshift. Notice the multiple images of the accretion disk.

22. February 25, 2003Lynn Cominsky - Cosmology A35022 Andrew Hamilton’s black hole simulator  In orbit around a Schwarzschild black hole, shooting simple cubes at it. The probes appear correctly lensed, redshifted, and time-delayed. Some probes are still en route to the black hole, while others, the red ones, appear frozen at the horizon.

23. February 25, 2003Lynn Cominsky - Cosmology A35023 Hamilton’s black hole trajectory  Minimum stable orbit is at 3 Schwarzschild radii or 300 km for this 30 M o black hole  In order to orbit any closer, you must fire thrusters to maintain forward motion

24. February 25, 2003Lynn Cominsky - Cosmology A35024 Hamilton’s orbiting a black hole  Orbiting the black hole at close to the photon sphere. We are moving at almost the speed of light, so the relativistic beaming effects are quite strong.

25. February 25, 2003Lynn Cominsky - Cosmology A35025 Spacetime activity  Bedsheet, small balls and heavy weight  Try rolling the balls across the sheet with and without the weight  Can you make a small ball curve in an orbit around the weight?

26. February 25, 2003Lynn Cominsky - Cosmology A35026 Bob Nemiroff’s black hole movies  Approaching a black hole  Circling the black hole

27. February 25, 2003Lynn Cominsky - Cosmology A35027 Nemiroff’s black hole movies  Approaching the photon sphere  Circling the BH at the photon sphere

28. February 25, 2003Lynn Cominsky - Cosmology A35028 Hamilton’s Wormhole  Complete Schwarzschild geometry consists of a black hole, a white hole, and two Universes connected at their horizons by a wormhole, also known as the Einstein-Rosen bridge

29. February 25, 2003Lynn Cominsky - Cosmology A35029 Hamilton’s charged black hole passage  Passing inward through the inner horizon of a charged black hole. The point at the center of the black disk is an image of our Universe, infinitely blueshifted, and should appear as an infinitely bright flash of light. The entire history of the Universe passes in that point. The region around the black disk also appears blue-shifted and brightened.

30. February 25, 2003Lynn Cominsky - Cosmology A35030 Hamilton’s black hole into white hole  Passing back through the inner horizon of a charged BH, into a white hole. The point at the center of the black disk is an infinitely blueshifted image of our Universe, that appears as an infinitely bright flash of light. The entire future of the Universe passes in that point. The point where we entered the inner horizon is at the bottom, and the point where we are exiting the horizon is at the center of the black disk.

31. February 25, 2003Lynn Cominsky - Cosmology A35031 Hamilton’s white hole into new Universe  Exiting the white hole into a new Universe, which appears as an infinitely blueshifted, infinitely bright, point at the center of the black disk. We see the entire history of the new Universe in the point. The noise texture continues to show how gas accreting on to the black hole in our original Universe would appear lensed and redshifted.

32. February 25, 2003Lynn Cominsky - Cosmology A35032 Hamilton’s looking back on our Universe  We are now in the new Universe, looking back at the white hole from which we have emerged. The new Universe is painted with the 2MASS Milky Way image. The view is redshifted and dimmed by our motion away from the white hole. Through the white hole we see light from our original Universe, multiply imaged.

33. February 25, 2003Lynn Cominsky - Cosmology A35033 Hamilton’s escape from white hole universe  If we accelerate back towards the white hole, in a frantic attempt to get back to our own Universe, we find that the white hole spontaneously turns into a black hole as we approach it. The accretion disk has been turned off for clarity.

34. February 25, 2003Lynn Cominsky - Cosmology A35034 Gravitational Radiation The strongest signal comes from two black holes Black hole mergers in distant galaxies will test General Relativity in the extreme  General Relativity predicts the existence of gravitational radiation  waves of gravity that travel at the speed of light

35. February 25, 2003Lynn Cominsky - Cosmology A35035 LIGO Prototype Detector Laser Interferometric Gravitational Observatory Engineering tests in 2003

36. February 25, 2003Lynn Cominsky - Cosmology A35036 Measuring Black Holes  Mass and spin of black hole can be measured from the gravitational radiation patterns emitted in different situations Distorted Schwarzschild black hole Distorted Kerr black hole

37. February 25, 2003Lynn Cominsky - Cosmology A35037 Colliding Black Holes  Spiral waveform can be calculated reliably  Ringdown after merger tells you the mass  Larger computers needed to predict the actual collision waveforms

38. February 25, 2003Lynn Cominsky - Cosmology A35038 Colliding Black Holes  Movie shows the event horizons merging as two black holes collide to form one larger black hole movie

39. February 25, 2003Lynn Cominsky - Cosmology A35039 Colliding Black Holes  Movie shows the blue and yellow gravitational waves emitted as the green event horizons of two black holes collide to form one larger black hole movie

40. February 25, 2003Lynn Cominsky - Cosmology A35040 Laser Interferometer Space Antenna  BH binaries  BH collisions  Galactic binaries Launch 2010+

41. February 25, 2003Lynn Cominsky - Cosmology A35041 Image a Black Hole! 0.1 arc sec resolution HST ImageM87 MAXIM 0.1 micro arc sec resolution 4-8  arc sec Close to the event horizon the peak energy is emitted in X-rays Micro-Arcsecond X-ray Imaging Mission

42. February 25, 2003Lynn Cominsky - Cosmology A35042 MAXIM Concept 32 optics (300  10 cm) held in phase with 600 m baseline to give 0.3 micro arc sec 34 formation flying spacecraft 1 km Optics 10 km Combiner spacecraft 500 km Detector spacecraft Black hole image! System is adjustable on orbit to achieve larger baselines

43. February 25, 2003Lynn Cominsky - Cosmology A35043 Stephen Hawking  “God not only plays dice, he also sometimes throws the dice where they cannot be seen.”  “My goal is simple. It is complete understanding of the universe, why it is as it is and why it exists at all.”  “It is not clear that intelligence has any long-term survival value.”  Proved that if GR is true and the universe is expanding, then a singularity existed at the birth of the universe

44. February 25, 2003Lynn Cominsky - Cosmology A35044 Hawking Radiation  Hawking radiation results from the formation of virtual particle pairs near the black hole’s event horizon. The total energy of the pair, E 1 +E 2 =0.  According to quantum mechanics, virtual pairs of particles are always being created from the vacuum – they usually annihilate, disappearing back into the vacuum  However, if the pair is formed near a black hole, one particle can become real (E 1 >0) and escape, while the other falls into the black hole  The escaping particle makes Hawking radiation, while to conserve energy, the particle that falls in has to have E 2 <0, which lowers the energy of the black hole, and eventually causes it to evaporate.

45. February 25, 2003Lynn Cominsky - Cosmology A35045 Hawking Radiation  Hawking predicted that black holes should radiate due to the emission of charged particles  Bigger black holes are colder and fainter  Hawking radiation will eventually lead to the death of BH at the end of time Hawking radiation from a very small black hole Evaporation of mini- black hole in a gamma-ray burst

46. February 25, 2003Lynn Cominsky - Cosmology A35046 Frame Dragging  Predicted by Einstein’s theory of General Relativity  Rotating bodies drag space and time around themselves as they rotate – like a spinning object stuck in molasses  It may have been observed by RXTE in neutron star and black hole binaries in oscillations caused by matter in precessing accretion disks Precessing top

47. February 25, 2003Lynn Cominsky - Cosmology A35047 Frame Dragging  Gravity Probe B – to be launched in 2003  Will test 2 predictions of GR using 4 extremely accurate gyroscopes Measure space-time reference frame of Earth – gyroscopes will move 6.6 arcseconds per year Measure frame dragging of Earth – gyroscopes will move by 42 milliarcseconds per year These two effects are at right angles to each other

48. February 25, 2003Lynn Cominsky - Cosmology A35048 Frame dragging activity  Paper plate, honey, peppercorns, food dye, superball  What happens when the ball spins? movie

49. February 25, 2003Lynn Cominsky - Cosmology A35049 Web Resources  Pictures from the Hubble Space Telescope http://oposite.stsci.edu/pubinfo/pictures.html http://oposite.stsci.edu/pubinfo/pictures.html  Chris Hillman’s Relativity Page http://www.math.washington.edu/~hillman/relativity.html  Andrew Hamilton’s Black Hole Flight Simulator http://casa.colorado.edu/~ajsh/bhfs/screenshots/ http://casa.colorado.edu/~ajsh/bhfs/screenshots/  Stephen Hawking’s Home page http://www.hawking.org.uk/ http://www.hawking.org.uk/  Genzel Group Milky Way BH video http://www.eso.org/outreach/press-rel/pr-2002/pr-17- 02.html#vid-02-02

50. February 25, 2003Lynn Cominsky - Cosmology A35050 Web Resources  Rossi X-ray Timing Explorer http://oposite.stsci.edu/pubinfo/pictures.html http://oposite.stsci.edu/pubinfo/pictures.html  Gravity Probe B http://einstein.stanford.edu  Micro-Arcsecond X-ray Imaging Mission http://maxim.gsfc.nasa.gov http://maxim.gsfc.nasa.gov  Laser Interferometric Space Array http://lisa.nasa.gov http://lisa.nasa.gov  Bob Nemiroff’s black hole movies http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html