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Searching for Gravitational Waves with Millisecond Pulsars:

Searching for Gravitational Waves with Millisecond Pulsars:. Dan Stinebring Oberlin College CWRU – May 21, 2009. George Greenstein (Amherst College). Discovery of “Millisecond” Pulsars. 1982 – Arecibo Observatory – Don Backer, Sri Kulkarni, ... Spun-up by accretion in a binary system

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Searching for Gravitational Waves with Millisecond Pulsars:

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  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 • 108 – 1010 years old (compared to 106 – 107) • Timing precision < 1 ms 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. 2 free masses space motion in this dimension is meaningless The masses track each other with lasers What is a gravitational wave? • A 2-D analogy

  10. each slice is a section of an arc of constant radius The gravitational wave is a wave of curvature

  11. As a gravitational wave passes through the space... the free masses remain fixed at their coordinate points while the distance between them

  12. increases due to the extra space in the curvature wave. The laser signal has to cover more distance and is delayed

  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

  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. Timing residuals for PSR B1855+09 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. 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(tthen, xpsr) – h(tnow, xEarth)

  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 ZavenArzoumanian, 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 VladKondratiev, 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)

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

  26. Dan Stinebring Oberlin College dan.stinebring@oberlin.edu 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 iscritical to detecting gravitational waves in the next decade. • What is needed: more pulsars, more telescope time, reduction in systematics.

  27. (1) Bertotti, Carr, & Rees (1983) Only get a non-oscillatory term when wuL << 1

  28. Bertotti, Carr, & Rees (1983)

  29. Compact object inspiral

  30. Bertotti, Carr, & Rees (1983)

  31. less space Quadrupole Gravitational Waves a ring of free test masses h+ more space

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

  33. 1133+16 dyn & sec linear grayscale logarithmic grayscale

  34. 1133+16 dyn & sec dynamic (or primary) spectrum secondary spectrum linear grayscale logarithmic grayscale

  35. Cumulative Delay - Arclets

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

  37. Black slide

  38. Pulsars are different from VIRGO, etc. • The only h (t, x) that matters is h (temission, xpulsar) and h (tarrival, xEarth). • 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.

  39. 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)

  40. LISA: Laser Interferometer Space Antenna • ESA – NASA project • Orbits Sun, 20o 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)

  41. Detection of Gravitational Waves (NASA GSFC) • Prediction of general relativity and other theories of gravity • Generated by acceleration of massive object(s) • 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 R. N. Manchester (ATNF) (K. Thorne, T. Carnahan, LISA Gallery)

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

  43. Comparison of Dyn/Sec spectra

  44. Cumulative Delay - No Arclets

  45. 1133+16 dyn & sec D. Hemberger

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