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Delensing Gravitational Wave Standard Sirens

Delensing Gravitational Wave Standard Sirens. Dr Martin Hendry Astronomy and Astrophysics Group, Institute for Gravitational Research Dept of Physics and Astronomy, University of Glasgow. Delensing Gravitational Wave Standard Sirens. Dr Martin Hendry

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Delensing Gravitational Wave Standard Sirens

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  1. Delensing Gravitational Wave Standard Sirens Dr Martin Hendry Astronomy and Astrophysics Group, Institute for Gravitational Research Dept of Physics and Astronomy, University of Glasgow

  2. Delensing Gravitational Wave Standard Sirens Dr Martin Hendry Astronomy and Astrophysics Group, Institute for Gravitational Research Dept of Physics and Astronomy, University of Glasgow With thanks to: David Bacon, Chaz Shapiro, Ben Hoyle ICG, Portsmouth See astro-ph/0907.3635; MNRAS in press

  3. Gravity in Einstein’s Universe “The greatest feat of human thinking about nature, the most amazing combination of philosophical penetration, physical intuition and mathematical skill.” Max Born Spacetime curvature Matter (and energy) Nottingham, March 2010

  4. Nottingham, March 2010

  5. Nottingham, March 2010 Gravity in Einstein’s Universe Spacetime tells matter how to move, and matter tells spacetime how to curve

  6. Nottingham, March 2010 Gravitational Waves • Produced by violent acceleration of mass in: • neutron star binary coalescences • black hole formation and interactions • cosmic string vibrations in the early universe (?) • and in less violent events: • pulsars • binary stars Gravitational waves • ‘ripples in the curvature of spacetime’ • that carry information about changing gravitational fields – or fluctuating strains in space of amplitude h where:

  7. Nottingham, March 2010 “Indirect” detection from orbital decay of binary pulsar: Hulse & Taylor Evidence for gravitational waves PSR 1913+16

  8. Nottingham, March 2010 Gravitational Waves: possible sources • Pulsed Compact Binary Coalescences: NS/NS; NS/BH; BH/BH Stellar Collapse (asymmetric) to NS or BH  • Continuous Wave Pulsars Low mass X-ray binaries (e.g. SCO X1) Modes and Instabilities of Neutron Stars  • Stochastic Inflation Cosmic Strings

  9. Nottingham, March 2010 Science goals of the gravitational wave field Fundamental physics and GR • What are the properties of gravitational waves? • Is general relativity the correct theory of gravity? • Is GR still valid under strong-gravity conditions? • Are Nature’s black holes the black holes of GR? • How does matter behave under extremes of density and pressure? Cosmology • What is the history of the accelerating expansion of the Universe? • Were there phase transitions in the early Universe?

  10. Nottingham, March 2010 Science goals of the gravitational wave field Astronomy and astrophysics • How abundant are stellar-mass black holes? • What is the central engine that powers GRBs? • Do intermediate mass black holes exist? • Where and when do massive black holes form and how are they connected to galaxy formation? • What happens when a massive star collapses? • Do spinning neutron stars emit gravitational waves? • What is the distribution of white dwarf and neutron star binaries in the galaxy? • How massive can a neutron star be? • What makes a pulsar glitch? • What causes intense flashes of X- and gamma- ray radiation in magnetars? • What is the star formation history of the Universe?

  11. Nottingham, March 2010 How can we detect them? • Gravitational wave amplitude h ~ L Sensing the induced excitations of a large bar is one way to measure this Field originated with J. Weber looking for the effect of strains in space on aluminium bars at room temperature Claim of coincident events between detectors at Argonne Lab and Maryland – subsequently shown to be false L + DL

  12. Nottingham, March 2010 VESF School on Gravitational Waves, Cascina May 25th - 29th 2009 How can we detect them? L + DL Jim Hough and Ron Drever, March 1978

  13. Nottingham, March 2010 31 yrs on - Interferometric ground-based detectors

  14. CONSTRUCTIVE (BRIGHT) + laser + DESTRUCTIVE (DARK) Nottingham, March 2010 It’s all done with mirrors Michelson Interferometer path 1 path 2

  15. Nottingham, March 2010 Detecting gravitational waves GW produces quadrupolar distortion of a ring of test particles Expect movements of less than 10-18 m over 4km Dimensionless strain

  16. GEO600 Nottingham, March 2010 Ground based Detector Network – audio frequency range LIGO Hanford TAMA, CLIO 300 m100 m 600 m 4 km2 km LIGO Livingston LIGO Livingston 3 km VIRGO 4 km P. Shawhan, LIGO-G0900080-v1

  17. Nottingham, March 2010 State of the Universe: March 2010 Some key questions for cosmology: • What is driving the cosmic • acceleration? • Why is 96% of the Universe • ‘strange’ matter and energy? • Is dark energy = Λ ? • How, and when, did galaxies • evolve? • Big bang + inflation + gravity = LSS?

  18. Nottingham, March 2010 State of the Universe: May 2010 WMAP5 BAO: 2dFGRS+SDSS SNIa: ‘union’ sample HSTKP From Kowalski et al (2008)

  19. Nottingham, March 2010 State of the Universe: March 2010 Some key questions for cosmology: • What is driving the cosmic • acceleration? • Why is 96% of the Universe • ‘strange’ matter and energy? • Is dark energy = Λ ? • How, and when, did galaxies • evolve? • Big bang + inflation + gravity = LSS? What rôle could gravitational waves play in answering these questions?

  20. Precision probe of relation on cosmological scales

  21. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Much recent interest in Following original idea in Schutz (1986); ‘Standard Sirens’ see also Cutler & Flanagan (1994) ‘Chirping’ waveform Chirp mass amplitude Measure time

  22. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Much recent interest in ‘Standard Sirens’: e.g. SMBHs at cosmological distances, for which DL can in principle be determined to exquisite accuracy. Inspiral waveform strongly dependent on SMBH masses. Since amplitude falls off linearly with (luminosity) distance, measured strain determines the distance of the source to high precision. Long tail due to parameter degeneracies Holz and Hughes 2005

  23. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes What could we do with standard sirens? • Completely independent, gravitational, calibration of • the distance scale and the Hubble parameter • Useful adjunct to existing constraints from CMBR, BAO, • subject to completely different systematic errors. • High precision probe of • Extension of beyond the reach of SNIe and BAO. Are these goals realistic?...

  24. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Currently three major issues: • Identification of E-M counterpart • Impact of weak lensing • Predicting merger event rates

  25. Nottingham, March 2010 Determining source directions Directions via 2 methods: AM & FM • FM: Frequency modulation due to orbital doppler shifts • Analogous to pulsar timing • gives best resolution for f > 1 mHz • AM: Amplitude modulation due to change in orientation of array with respect to source over the LISA orbit • AM gives best resolution for f < 1 mHz LISA will have sub-degree resolution for strong, SMBH sources See e.g. Cutler (98), Hughes (02), Cornish & Rubbo (03), Vecchio (04), Lang & Hughes (06)

  26. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Identifying an E-M counterpart: • GWs are redshifted, just like E-M radiation. • Hence we determine (very precisely) • If our goal is to probe e.g. how varies with • we can assume and break the • degeneracy. (See e.g. Hughes 02, Sesana et al. 07, 08) • If we want to use sirens to measure , • we must observe the E-M counterpart. • For this we need an accurate sky position!

  27. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Lang & Hughes (2006) include spin-induced precession of the SMBHs (See Vecchio 2004). This significantly improves estimation of sky position and .

  28. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Lang & Hughes (2006) include spin-induced precession of the SMBHs (See Vecchio 2004). This significantly improves estimation of sky position and .

  29. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes Lang & Hughes (2008) extend analysis to consider pre-merger evolution Sky position error ellipses shown at 28, 21, 14, 7, 4, 2, 1 and 0 days before the merger. Largest effect seen during final day – spin effects less important earlier. Similar analysis in Kocsis et al (2007)

  30. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes So what exactly can we do with sirens?.... Adapted from Holz & Hughes (2005)

  31. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes So what exactly can we do with sirens?.... Adapted from Holz & Hughes (2005)

  32. Nottingham, March 2010 Gravitational Wave Sources as Cosmological Probes GW sources will be (de-)magnified by weak lensing due to LSS. Same effect as for SN [ See e.g. Misner, Thorne & Wheeler; Varvella et al (2004), Takahashi (2006) ]. However, WL has much greater impact for sirens, because of their much smaller intrinsic scatter. Weak lensing may also limit identification of E-M counterpart

  33. Correcting for weak lensing?... Weak lensing by intervening large-scale structure distorts images of background galaxies Distortion matrix: Shear Convergence Following Refregier 2003

  34. Nottingham, March 2010 Correcting for weak lensing?... • Observed siren brightness • increased by magnification • What can we expect? • Can measure from shear • maps derived from simulations • Typically at • which means ~5% error in • Could we correct individual • sirens by mapping on small • angular scales?

  35. Nottingham, March 2010 Correcting for weak lensing?... • Dalal et al (2003) concluded • cosmic shear maps too noisy • on sub-arcminute scales. Unlensed Lensed

  36. Nottingham, March 2010 Correcting for weak lensing?... • Dalal et al (2003) concluded • cosmic shear maps too noisy • on sub-arcminute scales. • Following Bacon (2008): • → 3.8% at • Templating? Jönsson et al (2006) • Find galaxies near to line of sight to siren. • ‘Pin’ on realistic DM halos. → 2.5% • But what about ‘dark’ halos?...Systematics?... Unlensed Lensed

  37. Nottingham, March 2010 Correcting for weak lensing?...

  38. Nottingham, March 2010 Correcting for weak lensing?... • Shapiro et al (2009): Shear varies from place to place. • Gradient of shear → arcing, or flexion • see e.g. Bacon (2005) • Can measure flexion from galaxy survey, giving better estimate of • matter density on small angular scales. → 1.8% at • → 1.4% at

  39. Nottingham, March 2010 Correcting for weak lensing?... • Shapiro et al (2009): Shear varies from place to place. • Gradient of shear → arcing, or flexion • Can measure flexion from galaxy survey, giving better estimate of • matter density on small angular scales. → 1.8% at • → 1.4% at Major ‘multimessenger’ challenge

  40. Nottingham, March 2010 Correcting for weak lensing?... • Can measure flexion from galaxy survey, giving better estimate of • matter density on small angular scales. → 1.8% at • → 1.4% at No correction EUCLID Shear map only, ELT Shear + flexion, ELT + Space Shear + flexion, ELT EELT Major ‘multimessenger’ challenge

  41. Nottingham, March 2010 What could be done from the ground? Dalal et al. (2006): Short-duration GRBS, due to NS-NS mergers, will also be observed by ALIGO network. First optical observation of a NS-NS merger? GRB 080503 (Perley et al 2008)

  42. Nottingham, March 2010 What could be done from the ground? Dalal et al. (2006): Short-duration GRBS, due to NS-NS mergers, will also be observed by ALIGO network. Beaming of GRBs (blue curves), aligned with GW emission, could boost GW SNR. All-sky monitoring of GRBs + 1 year operation of ALIGO network  H0 to ~2% ?

  43. Nottingham, March 2010 What could be done from the ground? • Nissanke et al. (2009): • Very thorough treatment. • Considers impact of: • siren true distance; • no. of detectors in network; • Identifies strong degeneracy • between distance and inclination. • Need E-M observations / • beaming assumption to break this? • to 10 – 30% at 600 Mpc (NS-NS); 1400 Mpc (NS-BH). • Competitive with traditional ‘distance ladder’; probe of peculiar velocities?

  44. Nottingham, March 2010 Looking ahead to the Einstein Telescope… Third Generation Network — Incorporating Low Frequency Detectors • Third-generation underground facilities are aimed at having excellent sensitivity from ~1 Hz to ~104 Hz. • This will greatly expand the new frontier of gravitational wave astrophysics. Recently begun: Three year-long European design study, with EU funding, underway for a 3rd-generation gravitational wave facility, the Einstein Telescope (ET). Goal: 100 times better sensitivity than first generation instruments.

  45. Nottingham, March 2010 Looking ahead to the Einstein Telescope… Third Generation Network — Incorporating Low Frequency Detectors • Third-generation underground facilities are aimed at having excellent sensitivity from ~1 Hz to ~104 Hz. • This will greatly expand the new frontier of gravitational wave astrophysics. Recently begun: Three year-long European design study, with EU funding, underway for a 3rd-generation gravitational wave facility, the Einstein Telescope (ET). Goal: 100 times better sensitivity than first generation instruments.

  46. Nottingham, March 2010 Looking ahead to the Einstein Telescope… Sathyaprakash et al. (2009): ~106 NS-NS mergers observed by ET. Assume that E-M counterparts observed for ~1000 GRBs, 0 < z < 2. De-lensed Weak lensing Fit , , Competitive with ‘traditional’ methods

  47. …And even further ahead to BBO…

  48. Nottingham, March 2010 …And even further ahead to BBO… BBO schematic Cutler and Holz (2009): ~3 x 105 sirens observed, with unique E-M counterparts, for 0 < z < 5. Extremely good angular resolution, even at z = 5! Robust E-M identification of host galaxy, for determining redshift

  49. Nottingham, March 2010 …And even further ahead to BBO… Cutler and Holz (2009): ~3 x 105 sirens observed, with unique E-M counterparts, for 0 < z < 5. Simulated Hubble diagram, including effects of lensing

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