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The Search for Black Holes and Gravitational Waves: The Ultimate Tests of Einstein’s Relativity

The Search for Black Holes and Gravitational Waves: The Ultimate Tests of Einstein’s Relativity. Edmund Bertschinger MIT Department of Physics and Kavli Institute for Astrophysics and Space Research. What is a black hole?. A massive spacetime curvature singularity,

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The Search for Black Holes and Gravitational Waves: The Ultimate Tests of Einstein’s Relativity

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  1. The Search for Black Holes and Gravitational Waves:The Ultimate Tests of Einstein’s Relativity Edmund Bertschinger MIT Department of Physics and Kavli Institute for Astrophysics and Space Research

  2. What is a black hole? A massive spacetime curvature singularity, Surrounded by an event horizon (a point or ring of infinite density and tidal acceleration) (a spacetime boundary between causally disconnected regions of the universe)

  3. Einstein’s Strangest Theory:Curved Space, Warped Time The gravity of massive objects can make space non-Euclidean: Cosmology: Black hole:

  4. Are Black Holes Giant Spacetime Trampolines? What does Stephen Hawking say? Figure from NASA/GSFC Imagine

  5. ct y x Einsteinian time warps My worldline (trajectory) If you pass inside this cone, I can communicate with you! Minkowski diagram without a black hole

  6. i was considering howwithin night's loosesack a star'snibbling in- fin-i-tes-i-mal-ly devours darkness thehungry starwhichwill e.-ventu-al-ly jigglethe bait ofdawn and be jerked into eternity. when over my head ashootingstarBurs (tinto a stale shrieklike an alarm-clock) -- e.e. cummings Collapse through the horizon: N. Rumiano, http://nrumiano.free.fr/Eindex.html

  7. What happens at the event horizon? Classically, nothing — it’s just a dangerous border crossing. Quantum mechanically, Hawking radiation • Particle vacuum state fluctuates with creation/annihilation of virtual pairs of particles • Negative energy particles fall in, positive energy ones escape, black hole loses mass as blackbody radiation • Completely negligible for astrophysical black holes

  8. How can matter escape from a BH? Hawking radiation is extremely weak and may never be observed. Yet it raises profound questions of quantum gravity that perhaps only Superstring Theory will be able to answer! Quantum tunneling produces a Particle-Antiparticle pair from the vacuum! http://superstringtheory.com/blackh/blackh3.html

  9. Black holes in Nature The afterlife of giant stars Black hole masses 3-15 solar masses Giant sinkholes in galaxy centers Black hole masses million to billion solar masses

  10. How we find black holes (and neutron stars): X-rays! MIT-led Rossi X-Ray Timing Explorer satellite, launched 1995

  11. How do black holes emit X-rays? They get indigestion from eating a companion star, which gets compressed and heated in an accretion disk! Artistic conception 1 Artistic conception 2

  12. How can we prove these are the BH of Einstein’s theory? Measure the gravitational waves emitted as two black holes merge.

  13. Gravitational Radiation Newtonian gravity is action at a distance, in clear violation of the principle of relativity. How does general relativity fix this? • By adding WAVES that travel at the speed of light How are they produced and how are scientists preparing to detect them? • Produced by accelerating masses: for example, two black holes merging • Detected by their TINY effect on test masses, using LASERS bouncing back and forth between moving mirrors

  14. Gravitational waves — the Evidence Neutron Binary System – Hulse & Taylor (Nobel Prize) PSR 1913 + 16 -- Timing of pulsars 17 / sec · ~ 8 hr · • Neutron Binary System • separated by 106 miles • m1 = 1.4m; m2 = 1.36m; e = 0.617 • Prediction from general relativity • spiral in by 3 mm/orbit • rate of change orbital period

  15. Left: Artist’s conception of gravitational waves produced by a binary system Bottom: LIGO design http://www.ligo.caltech.edu/

  16. Effect of a GW on matter

  17. Global network of detectors GEO VIRGO LIGO TAMA AIGO LIGO • Detection confidence • Source polarization • Sky location LISA

  18. 3 0 3 ( ± 0 1 k 0 m m s ) LIGO: Laser Interferometer Gravitational-wave Observatory WA 4 km 2 km LA 4 km

  19. S2 2nd Science Run Feb - Apr 03 (59 days) S1 1st Science Run Sept 02 (17 days) Strain (1/rtHz) LIGO Target Sensitivity S3 3rd Science Run Nov 03 – Jan 04 (70 days) Frequency (Hz) Science Runs and Sensitivity DL = strain x 4000 m 10-18 m rms

  20. H1 strain sensitivity – S1 to S4+

  21. What’s the latest? S5 (goals) • Sensitivity (in terms of inspiral reach) • H1 11 Mpc (10 to 14 Mpc) • H2 5 Mpc (6 to 9 Mpc) • L1 11 Mpc (10 to 14 Mpc) • Stability and duty cycle • 70% individual • 40% triple coincidence • Schedule • Started in November, 2005 • Get 1 year of data at design sensitivity • Enhancements over next 3 years • Advanced LIGO: 2008, 15 times more sensitive than initial LIGO

  22. Laser Interferometer Space Antenna (LISA, 2013+) • Three spacecraft • triangular formation • separated by 5 million km • Formation trails Earth by 20° • Approx. constant arm-lengths • Constant solar illumination 1 AU = 1.5x108 km

  23. LISA and LIGO

  24. Ultimate success…New Instruments, New Field, the Unexpected…

  25. Special Thanks to Prof. Nergis Mavalvala and the LIGO Scientific Collaboration YOU can get involved in LIGO data analysis: “Einstein at Home” http://einstein.phys.uwm.edu/

  26. Additional Credits and Information Credits: Black hole animated gif courtesy Andrew J.S. Hamilton Rossi X-Ray Timing Explorer figure courtesy NASA/Goddard Space Flight Center LIGO and other gravitational wave images courtesy Nergis Mavalvala Stephen Hawking’s voice was simulated and used without permission. Books: The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, Brian Greene (more advanced than The Fabric of the Cosmos) Black Holes and Time Warps: Einstein’s Outrageous Legacy, Kip S. Thorne (more advanced)

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