1. 1 Welcome to LIGO!

2. What Does the Universe Look Like? 2

3. The Constellation Orion (The Hunter) Credit: thcphotography.com Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

4. Orion in the UV Credit: Midcourse Space Experiment, Johns Hopkins Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

5. Zoom in - The Orion Nebula through the Hubble Space Telescope Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

6. 6 Orion Nebula in the Infrared Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

7. 7 Orion Nebula in Radio Waves Credit: NRAO Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

8. Orion Nebula in X- rays Credit: NASA/CXC/Penn State/E.Feigelson & K.Getman et al Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

9. 9 What about Black Holes? Courtesy: Wikimedia Radio Waves Micro- waves InfraredVisibleUVX-rayGamma ??

10. 10 LIGO – A New Way to Look at (or Listen to) the Universe

11. 11

12. 12 The Heart of LIGO – Vacuum Equipment Areas View inside Corner Station Standing at vertex beam splitter

13. 13 Local sensors/actuators provide damping and control forces Mirror is balanced on 1/100 th inch diameter wire to 1/100 th degree of arc Optics suspended as simple pendulums Pendulum suspensions give mirrors freedom of movement in the LIGO frequency band

14. 14 LIGO (Washington)LIGO (Louisiana) The Laser Interferometer Gravitational-Wave Observatory Brought to you by the National Science Foundation; operated by Caltech and MIT; the research focus for about 500 LIGO Science Collaboration members worldwide.

15. 15 Part of Future International Detector Network LIGO Simultaneously detect signal (within msec) detection confidence locate the sources decompose the polarization of gravitational waves GEO Virgo TAMA AIGO

16. 16

17. 17

18. 18

19. 19

20. 20 Today’s Talk General relativity framework Some potential gravitational wave sources Overview of interferometer operations Enhanced LIGO improvements With thanks to Michael Landry, Fred Raab, Vern Sandberg, Kate Dooley Dale Ingram LIGO Hanford Observatory ingram_d@ligo-wa.caltech.edu

21. 21 Geometry lies at the heart of general relativity

22. 22 General relativity tells us that spacetime has measurable properties such as curvature and stiffness John Wheeler’s view of Einstein’s description of space, time and gravity

23. 23 Curvature is real! Not only the path of matter, but even the path of light is affected by gravity from massive objects Einstein Cross Photo credit: NASA and ESA A massive object shifts apparent position of a star

24. 24 LIGO hunts for ripples in the curvature of space – gravitational waves Gravitational waves are ripples in the fabric of space. These ripples come from rapid motions of large concentrations of matter or energy. Rendering of space stirred by two orbiting black holes: By the time gravitational waves pass the earth, their effects are vanishingly small. Our detector must be sensitive enough to measure these effects

25. 25 Sources of Gravitational Waves: Supernovae

26. 26 The Spinning of Neutron Star Pulsars

27. 27 Inspirals -- the Loudest Sources

28. 28 LIGO listens for ripples in the curvature of space. These will produce vibrations of the interference pattern in the interferometer. Photosensors will record the vibrations. Inspiraling Neutron Stars Inspiraling Black Holes What might be the “sound” of gravitational waves?

29. 29 Why use interferometers as gravitational wave detectors? Gravitational waves shrink space along one axis as they stretch space along a perpendicular axis. Both axes are perpendicular to the direction of propagation. Mark the space at (x) and (y); look for the lengths of the ellipse axes to fluctuate

30. 30 The basic Michelson design provides the ability to monitor a circle of space Laser Beam Splitter End Mirror Screen

31. 31 Fabry Perot cavities and power recycling provide additional sensitivity Laser signal

32. 32 “Sensitivity” means displacement sensitivity – the ability of the detector to sense differential motions of the mirrors How sensitive? 0. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 m a meter a centimeter a millimeter a human hair one wavelength of light diameter of an atom LIGO displacement sensitivity diameter of a nucleus

33. 33 Enhanced LIGO – transition from 10W to 35W of laser power Prepared by AEI/LZH (Germany) World-leading performance in frequency and amplitude stability Base unit for Advanced LIGO

34. 34 More laser power requires enhanced input optics Faraday isolator re-polarizes and dumps returning light before it enters the laser enclosure IO R&D from University of Florida

35. 35 Beam path from PSL through HAM1 and HAM2 The Input Optics include all the elements from the EOM to the Mode-Matching Telescope. 35 Laser Reference cavity Pre-Mode Cleaner EOM Mode Cleaner Faraday isolator Recycling mirror Mode matching telescope airvacuum

36. 36 Vacuum chambers provide quiet homes for the mirrors View inside Corner Station Standing at vertex beam splitter

37. 37 Evacuated Beam Tubes Provide Clear Path for Light

38. 38 Local sensors/actuators provide damping and control forces Mirror is balanced on 1/100 th inch diameter wire to 1/100 th degree of arc Optics suspended as simple pendulums Pendulum suspensions give mirrors freedom of movement in the LIGO frequency band

39. 39 Core Optics Substrates: SiO2 »25 cm Diameter, 10 cm thick »Homogeneity < 5 x 10-7 »Internal mode Q’s > 2 x 106 Polishing »Surface uniformity < 1 nm rms »Radii of curvature matched < 3% Coating »Scatter < 50 ppm »Absorption < 2 ppm »Uniformity <10-3 Production involved 6 companies, NIST, and LIGO

40. 40 Suspended Core Optic

41. 41 BSC Passive Vibration Isolation

42. 42 Active vibration isolation in HAM 6 (detection chamber) Signals from on- board sensors are used in the actuation scheme ISI will provide a quiet platform for GW photodiodes Stanford R&D

43. 1/22/200943 ISI Install

44. 44 Isolated and suspended output mode cleaner OMC will remove ‘junk’ from detection port light In-vacuum (isolated) photodiodes tuned for DC readout scheme OMC – Caltech, GEO

45. 45 Additional eLIGO changes Upgraded Thermal compensation on inner mirrors Replace viton stop tips with silica tips Replace selected control system magnets with lower- noise versions Mount baffles to reduce stray light Intense commissioning continues to precede the start of S6

46. 46 Projected strain sensitivity for eLIGO Enhanced LIGO

47. 47 LIGO is operated by Caltech and MIT for the National Science Foundation NSF Cooperative Agreement # NSF-PHY-0757058 LIGO’s research efforts are directed by the LIGO Scientific Collaboration, composed of roughly 600 researchers at more than 40 domestic and international institutions. Apply for a summer research internship!

48. 48 Welcome to LIGO!

49. 49 Courtesy SOHO/NASA/ESA The Sun in H-alpha (visible) Radio Waves Micro- waves InfraredVisibleUVX-rayGamma

50. 50 Image courtesy of Astro-1 and Robert Gendler M81 in UV and visible

51. 51 Image courtesy of ESA/ROSAT The Crab in X-ray