1. Searching for Gravitational Waves with Millisecond Pulsars: Dan Stinebring Oberlin College CWRU – May 21, 2009

2. George Greenstein (Amherst College)

3. Discovery of “Millisecond” Pulsars 1982 – Arecibo Observatory – Don Backer, Sri Kulkarni,... Spun-up by accretion in a binary system 10 8 – 10 10 years old (compared to 10 6 – 10 7 ) Timing precision < 1  s is possible in many cases (as opposed to ≈ 1 ms)

4. Millisecond Pulsar Spin-up

5. B0329+54 The Vela pulsar The first millisecond pulsar (1982, Backer & Kulkarni)

6. Arecibo Observatory – the world’s largest radio telescope

7. Black slide

8. Sky Distribution of Millisecond Pulsars P < 20 ms and not in globular clusters R. N. Manchester (ATNF)

9. space What is a gravitational wave? A 2-D analogy motion in this dimension is meaningless 2 free masses The masses track each other with lasers Ron Hellings (Montana SU)

10. The gravitational wave is a wave of curvature each slice is a section of an arc of constant radius Ron Hellings (Montana SU)

11. the free masses remain fixed at their coordinate points As a gravitational wave passes through the space... while the distance between them Ron Hellings (Montana SU)

12. increases due to the extra space in the curvature wave. The laser signal has to cover more distance and is delayed Ron Hellings (Montana SU)

13. Why are gravitational waves called “a strain in space”? points that are close have little space injected between them points that are further away have more space injected between them Ron Hellings (Montana SU)

14. Black slide [Markus Pössel, AEI http://www.einstein-online.info/en/spotlights/gw_waves/index.html

15. Black slide [Markus Pössel, AEI http://www.einstein-online.info/en/spotlights/gw_waves/index.html

16. Black slide [Markus Pössel, AEI http://www.einstein-online.info/en/spotlights/gw_waves/index.html

17. Detecting Gravitational Waves with Pulsars Observe the arrival times of pulsars with sub-microsecond precision. Correct for known effects (spin-down, position, proper motion,...) through a multi-parameter Model Fit. Look at the residuals (Observed - Model) for evidence of correlated timing noise between pulsars in different parts of the sky. Timing residuals for PSR B1855+09 Arecibo data

18. Black slide R. N. Manchester

19. Black slide Correlation Expected between Pulsars in Different Directions F. Jenet (UTB)

20. Fact of Life #1 The gravitational effect is due only to what happens at the two ends of the path: h(t then, x psr ) – h(t now, x Earth )

21. Fact of Life #2 Fitting for unknown pulsar parameters removes power from the data: (P, dP/dt, position, angular motion, binary orbit,...) Blandford, Narayan, and Romani 1984

22. Anne Archibald, McGill University Zaven Arzoumanian, Goddard Space Flight Center Don Backer, University of California, Berkeley Paul Demorest, National Radio Astronomy Observatory Rob Ferdman, CNRS, France Paulo Freire, NAIC Marjorie Gonzalez, University of British Columbia Rick Jenet, University of Texas, Brownsville, CGWA Victoria Kaspi, McGill University Vlad Kondratiev, West Virginia University Joseph Lazio, Naval Research Laboratories Andrea Lommen, Franklin and Marshall College Duncan Lorimer, West Virginia University Ryan Lynch, University of Virginia Maura McLaughlin, West Virginia University David Nice, Bryn Mawr College Scott Ransom, National Radio Astronomy Observatory Ryan Shannon, Cornell University Ingrid Stairs, University of British Columbia Dan Stinebring, Oberlin College

23. The Gravitational Wave Spectrum Spectrum R. N. Manchester (ATNF)

24. Figure by Paul Demorest (see arXiv:0902.2968)

26. Summary Pulsars are ideal for detecting the low frequency (nHz) end of the gravitational wave spectrum. This technique is complementary to the LIGO and LISA efforts. Arecibo is critical to detecting gravitational waves in the next decade. What is needed: more pulsars, more telescope time, reduction in systematics. Dan Stinebring Oberlin College dan.stinebring@oberlin.edu

27. Bertotti, Carr, & Rees (1983) (1)

28. Bertotti, Carr, & Rees (1983)

29. Compact object inspiral

33. Bertotti, Carr, & Rees (1983)

35. Quadrupole Gravitational Waves a ring of free test masses h+h+ less space Ron Hellings (Montana SU) more space

37. Lorimer&Kramer (LK) Fig. 4.2 Sketch showing inhomogeneities in the ISM that result in observed scattering and scintillation effects.

38. 1133+16 dyn & sec logarithmic grayscale linear grayscale

39. 1133+16 dyn & sec logarithmic grayscale linear grayscale dynamic (or primary) spectrum secondary spectrum

40. Cumulative Delay - Arclets

41. Hemberger & Stinebring 2008, ApJ, 674, L37

42. Black slide

43. Pulsars are different from VIRGO, etc. The only h (t, x) that matters is h (t emission, x pulsar ) and h (t arrival, x Earth ). We don’t track the electromagnetic phase, but we do track the pulsar rotational phase (in the best cases to 100 ns resolution). Pulsars are located all over the sky. This is a GOOD thing because each pair is a separate detector.

44. LIGO: Laser Interferometer Gravitational-wave Observatory US NSF project Two sites: Washington State and Louisiana Two 4-km vacuum arms, forming a laser interferometer Sensitive to GW signals in the 10 – 500 Hz range Initial phase now commissioning, Advanced LIGO ~ 2011 Most probable astrophysical source: merger of double neutron- star binary systems R. N. Manchester (ATNF)

45. LISA: Laser Interferometer Space Antenna ESA – NASA project Orbits Sun, 20 o behind the Earth Three spacecraft in triangle, 5 million km each side Sensitive to GW signals in the range 10 -4 – 10 -1 Hz Planned launch ~2015 Most probable astrophysical sources: Compact stellar binary systems in our Galaxy and merger of binary black holes in cores of galaxies R. N. Manchester (ATNF)

46. Detection of Gravitational Waves Prediction of general relativity and other theories of gravity Generated by acceleration of massive object(s) (K. Thorne, T. Carnahan, LISA Gallery) Astrophysical sources:  Inflation era  Cosmic strings  Galaxy formation  Binary black holes in galaxies  Neutron-star formation in supernovae  Coalescing neutron-star binaries  Compact X-ray binaries (NASA GSFC) R. N. Manchester (ATNF)

47. What we can measure... ISM impulse response function the autocorrelation of the impulse response At the moment, we use the centroid of

48. Comparison of Dyn/Sec spectra

49. Cumulative Delay - No Arclets

50. 1133+16 dyn & sec D. Hemberger

51. B1737+13 tau_ss + errors (36 epochs) D. Hemberger

52. Detecting Gravitational Waves with Pulsars Observed pulse periods affected by presence of gravitational waves in Galaxy (psr at time of emission; Earth at time of reception) For stochastic GW background, effects at pulsar and Earth are uncorrelated Use an array of pulsars to search for the GW background that is correlated because of its effect on the Earth (at time of reception) Best limits are obtained for GW frequencies ~ 1/T where T is length of data span Timing residuals for PSR B1855+09 R. N. Manchester (ATNF) Want to achieve < 1 us residuals for 10 pulsars for 5 years

53. R. N. Manchester Sept 2006

54. data: R. N. Manchester

55. What we measure... ISM impulse response function ISM the autocorrelation of the impulse response At the moment, we use the centroid of

56. A new result... 6 months of ~ weekly Arecibo observations of a moderate DM pulsar (B1737+13) 4 x 50 MHz bands near 21 cm Investigate time variability of ScintArc structure and its effect on pulsar timing

57. B1737+13 secondary spectrum movie

58. 1133+16 dyn & sec D. Hemberger

59. 1133+16 dyn & sec D. Hemberger

60. Timing Residuals (Observed – Model) for PSR B1855+09

61. “Deflection of Pulsar Signal Reveals Compact Structures in the Galaxy, ” A. S. Hill et al. 2005, 619, L17

62. The substructure persists and MOVES! Hill, A.S., Stinebring, D.R., et al. 2005, ApJ,619, L171 This is the angular velocity of the pulsar across the sky!

63. Brisken dyn + secondary 1.2 Walter Brisken (NRAO) et al. “Small Ionized and Neutral Structures,” Socorro, NM, 2006 May 23

64. How Does this Work?

65. Coherent radiation scatters off electron inhomogeneities ~ 1 kpc ~ 10 mas

66. Multi-path interference causes a random diffraction pattern

67. Relative transverse velocities produce a dynamic spectrum time

68. Scattering in a thin screen plus a simple core/halo model can explain the basics of scintillation arcs

69. Time variability of scintillation arcs will allow probing of the ISM on AU size scales

70. Kolmogorov vs. Gaussian PSF How to produce a “core/halo” psf? A Gaussian psf will NOT work: No halo.

71. Kolmogorov vs. Gaussian PSF Kolmogorov turbulence DOES work It produces a psf with broad wings

72. conjugate time axis Conjugate time axis (heuristic) d D y V incident plane wave ( )

73. conjugate freq axis Conjugate frequency axis (heuristic) D incident plane wave ( )

74. where do the parabolas come from ?” Where do the parabolas come from?

75. parabola eqn on data plot B2021+25

76. Walker et al. 2004 1d “image” on the sky where do the arclets come from ?” Where do the “arclets” (inverted parabolas) come from?

77. Some Observational Highlights...

78. The Earth Orbits the Sun !!

79. Effective Velocity Cordes and Rickett 1998, ApJ, 507, 846

80. 1929+10 velocity plot

81. Multiple Arcs —> Multiple “Screens”

82. “Screen” Locations f =  f t 2

83. PSR 1133+16 proper motion (2d) s=0s=1 f =  f t 2

86. Summary Pulsars are ideal probes of the ionized ISM New phenomena to explore and learn to interpret Pulsars may detect gravitational waves before the expensive detectors! Larger more sensitive telescopes will provide breakthroughs! LOFAR, SKA... Thanks to: Sterrewacht Leiden & NWO

87. Scintillation Arcs Underlie Other Scintillation Patterns

88. Tilted 0355a Roger Foster, GB 140 ft

89. Tilted 0355b Roger Foster, GB 140 ft

90. Tilted 0919a

91. Tilted 0919b

92. The Gravitational Wave Spectrum R. N. Manchester (ATNF)

93. Sky Distribution of Millisecond Pulsars P < 20 ms and not in globular clusters R. N. Manchester (ATNF)

94. Black slide [Markus Pössel, AEI http://www.einstein-online.info/en/spotlights/gw_waves/index.html

95. Black slide [Markus Pössel, AEI http://www.einstein-online.info/en/spotlights/gw_waves/index.html

96. Discovery of “Millisecond” pulsars in 1982 changed everythingBlack slide Timing residuals for PSR B1855+09

97. Black slide