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Gravitational-wave spin measurements and massive black hole evolution

Gravitational-wave spin measurements and massive black hole evolution. Emanuele Berti, University of Mississippi CENTRA, Jul 9, 2009. Outline 1) Evidence for BHs and BH binaries 2) Spin in inspiral, merger, ringdown 3) Physics and astrophysics from spin measurements.

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Gravitational-wave spin measurements and massive black hole evolution

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  1. Gravitational-wave spin measurements and massive black hole evolution Emanuele Berti, University of Mississippi CENTRA, Jul 9, 2009

  2. Outline1) Evidence for BHs and BH binaries2) Spin in inspiral, merger, ringdown3) Physics and astrophysics from spin measurements

  3. The SMBH at the center of our Galaxy (Movie courtesy of Reinhard Genzel)

  4. SMBH spin estimates: efficiency and ISCO h=0.42 h=1-(8/9)1/2=0.057

  5. Continuum spectroscopy: in the “high soft state” gas is optically thick, radiates like a blackbody; from radiation flux, estimate Rincosi/D Line spectroscopy:X-ray observations of “skewing” of the Fe Ka Fluorescence line Large uncertainties! EB, Cardoso & Starinets 0905.2975 Gravitational wave observations can do better

  6. Radiative efficiency and SMBH spin (Wang, Hu, Li, Chen, King, Marconi, Ho, Yan, Staubert & Zhang, 0904.1896) Why the spindown? Chaotic accretion? Were mergers more common in the past?

  7. SMBH binary formation and event rates 1) Black holes sink to the center by dynamical friction 2)Gravitational slingshot interactions (or gas accretion) increase the binary’s binding energy 3)Gravitational radiation drives binary to merger: eccentric binaries coalesce faster 4)Gravitational-wave recoil for unequal-mass binaries may kick BHs out of the host galaxy Massive (M~30-300Msun), metal-free Pop III stars collapse forming primordial, massive BHs in the cores of massive dark-matter halos (Volonteri, Haardt, Madau, Rees) Alternative: Direct collapse of low-angular momentum material in protogalactic discs to form large-mass seeds at large z>12 (Koushiappas et al.) Bottom line: maybe 10 events/year at 2<z<6; possible SMBH background! Matsubayashi et al., Miller, Portegies-Zwart et al. 05: a few, or up to 100 IMBH-SMBH/yr (~1000+106 Msun)

  8. Close SMBH binary candidates • 2002: NGC6240: projected distance ~1kpc (Komossaet al., astro-ph/0212099) • 2006: Radio Galaxy 0402+379: Mtot~1.5x108, projected separation ~7.3pc • (Rodriguez et al., astro-ph/0604042) • 2008: SDSSJ092712.65+194344.0: quasar with two sets of narrow lines, Dv~2650km/s • (one with associated broad lines) • Initial interpretation: recoiling BH (Komossa, Zhou & Lu, 0804.4585) • Binary interpretations: • Blueshifted lines from accretion stream within the inner rim of a circumbinary diskq~0.1, m1~109 (Bogdanovicet al., 0809.3262) • Blueshifted lines from gas swirling around secondaryq~0.3, m1~2x109, a~0.34pc, P~370yrs (Dottiet al., 0809.3446) • Superposition of two AGN? (Shields et al., 0810.2563) • Analogous to NGC 1275, large and small galaxy interacting (Heckman et al., 0810.1244) • 2009: SDSSJ153636.22+044127.0:quasar with two sets of broad lines, Dv~3500km/s • (absoption lines at intermediate velocity) • Binary interpretation (Boroson & Lauer, 0901.3779): q=1/40, m1~8x108, a~0.1pc, P~100yrs, may coalesce within a Hubble time • No superposition of two AGNs • May be analogous to NGC 1275 ?

  9. OJ 287: a SMBH binary near merger? Sep 13, 2008 M1=1.8x1010 Msun ,M2=108Msun ,e=0.66, a~50M, Df=39° Consistent with gravitational wave emission within 10%,Tmerge=104yrs (Valtonen et al., Nature, 0809.1280)

  10. Spin in inspiral, merger and ringdown

  11. Inspiral, merger and ringdown

  12. LISA signal-to-noise ratio for inspiral and ringdown ~10000 @ z=0.54 ~300 @ z=10 (EB, Cardoso & Will 06)

  13. Inspiral: (circular) Post-Newtonian waveforms Standard Post-Newtonian terms in black can be used to test GR (more later..) Spin-orbit, 1.5PN Spin-spin, 2PN Brans-Dicke: dipole radiation - best bounds from NS-IMBH Massive graviton: D-dependent delay in wave propagation Best bounds from SMBH binaries

  14. Parameter estimation (in a nutshell) Gravitational-wave signal described by parameters{li} Inspiral: {li} = masses, spins, sky location, orbital orientation.. Ringdown: {li} = mass, angular momentum, spin orientation, sky location.. For high SNR, errors have a Gaussian distribution: where the Fisher matrix Errors on and correlations between parameters are given by the correlation matrix: (see Vallisneri 07 for caveats)

  15. Inspiral: tracking Msource(z), Jsource(z) LISA only measures redshifted combinations of masses and spins of the form M=(1+z)Msource J=(1+z)2Jsource Measuring luminosity distance DL(z,cosmology) and assuming cosmology is known, find z(DL) and remove degeneracy Luminosity distance Angular resolution (steradians) Reduced mass “Chirp” mass (EB, Buonanno & Will 05)

  16. Spin precession (Kidder 95)

  17. Simple precession vs. transitional precession (Apostolatos, Cutler, Sussman & Thorne 94)

  18. Spin-orbit induced alignment? (Schnittman 04)

  19. Ringdown: black hole spectroscopy wlmn=wR+iwI=2pf+i/t f= 0.012 (106Msun)/M Hz t = 55 M/(106Msun) s

  20. Spectroscopy of rotating (Kerr) black holes

  21. Mergers: kick velocities and final spin (EB et al. 2007; Rezzolla et al. 2007-2009) Kicks for spinning binaries as large as 4000 km/s (Campanelli et al., Jena group) Spin expansion: spin and kicks using symmetry arguments and a few simulations (Boyle, Kesden & Nissanke 2007) (Buonanno, Kidder & Lehner 2007) Very good agreement (~few %) between different models for aligned/antialigned spins

  22. Typical final spin from MBH mergers * Without alignment, isotropic mergers (on average) are unlikely to produce spins >0.7 * Alignment (presumably) requires torques from accretion disks (Bogdanovic et al., astro-ph/0703054)

  23. Physics and astrophysics from spin measurements

  24. (Lang & Hughes 06) Random spins m1=106 (solid) m2=3x105 (dashed) m1=106, m2=3x105 c1=c2=0.9 (solid) c1= c2=0.1 (dashed)

  25. Errors on single-mode detection with LISA DL=3Gpc, erd=3% Errors scale like SNR-1~erd-1/2 (EB, Cardoso & Will 06)

  26. f(M,j),t(M,j) M(f,t), j(f,t) Ringdown: no-hair tests • One-mode detection: • Measure of black hole’s mass and angular momentum (Echeverria 89, Finn 92) • Multi-mode detection: • First mode yields (M,j) • In GR, quasinormal frequencies depend only on M and j: second mode yields test that we are observing a rotating black hole • Under reasonable assumptions, the test requires SNR~10-100 (EB, Cardoso & Will 06) • Test similar in nature to “multipolar mapping” with EMRIs • Test should be possible both with LISA and with advanced LIGO (EB et al. 07)

  27. Spin distribution encodes merger history • Assume isotropy and zero spins for the “seed” black holes (for this plot only!) • Consider for simplicity three scenarios: • Inefficient accretion (evolution by mergers only): attractor at spin ~0.7 • Prolonged accretion (Bardeen-Petterson), producing spinup • Chaotic accretion (King & Pringle) , producing spindown (EB & Volonteri, 0802.0025)

  28. LISA science: parameter estimation accuracy Depends on descoping. We considered the 6-link and baseline designs (Arunet al., 0811.1011) May not lose much in terms of detected merger events, but dramatic loss for source localization and distance determination (and loss of EMRI science) Punchline: descopes would seriously damage the science you can do with LISA

  29. Fundamental physics: the graviton mass (EB, Buonanno & Will, gr-qc/0411129; Arun & Will, 0904.1190)

  30. Summary • EM observations yield model-dependent spin estimates • Inspiral/ringdown: measure spins with accuracy ~1% or better • Spin evolution encodes SMBH merger history • Seed formation scenarios determine mass evolution/event rates • Accretion (efficient/chaotic/inefficient) determines spin distribution • Astrophysics: how efficient is alignment? • Affects ejection rates (and LISA event rates) • Affects LISA parameter estimation accuracy/requirements • Fundamental physics with massive black hole binaries • Inspiral: graviton mass • Ringdown: no-hair tests • Inspiral+Ringdown: Hawking’s area theorem

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