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The Astrophysics of Gravitational Wave Sources

The Astrophysics of Gravitational Wave Sources. Conference Summary: Ground-Based Detectors (1-10 4 Hz) Kimberly New, LANL. Detection & Data Analysis: LIGO & GEO’s science runs Brady & Mavalvala. high sensitivity, large bandwidth, hours of coincident operation searches

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The Astrophysics of Gravitational Wave Sources

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  1. The Astrophysics of Gravitational Wave Sources Conference Summary: Ground-Based Detectors (1-104 Hz) Kimberly New, LANL

  2. Detection & Data Analysis: LIGO & GEO’s science runsBrady & Mavalvala • high sensitivity, large bandwidth, hours of coincident operation • searches • NS/NS chirps, bursts, known pulsars, stochastic bkgd. • techniques used • science implications

  3. Detection & Data Analysis: Detectors in 2012Finn • interferometers - sensitivity improvements • <50 Hz: improve seismic isolation • active isolation • multiple levels of suspension • 50-200 Hz: mitigate thermal noise • suspension system (increase mass, used fused silica ribbon) • test masses (sapphire) • >200 Hz: reduce shot noise • increase laser power

  4. Detection & Data Analysis: Detectors in 2012Finn • resonant acoustic detectors • current sensitivity 10-22 near 900 Hz (1 Hz bandwidth) • future • spheres, spheres within spheres • 100 Hz bandwidth near 1 KHz (with improved amplifiers) • gravitational wave astronomy • NS/NS coalescence to 400 Mpc • stellar BH/BH coalescence to z=0.5 • pulsars ( ~ 10-6 at 102 Hz)

  5. Sources: BinariesSchutz, Centrella, Bulik, Heyl • BH/BH Coalescence (Centrella, Schutz) • LIGO: stellar mass BH/BH binary final coalescence • signal will contain astrophysically rich info: spins, strong field GR • simulations of vacuum field eqns. scale w/ mass & spin • evolve single BHs for 103M ! • binary BHs for 102M (~orbital period) ! • “Discovery Channel” simulation of merger (AEI) • simulation of ringdown w/Lazarus perturbative code • remaining numerical issues • stability (formalism, gauge choices, boundary conditions) • physical initial data • waveform extraction

  6. Sources: BinariesSchutz, Centrella, Bulik, Heyl • chirp mass measurement could constrain binary evolution • parameter studies with population synthesis code (Bulik, Kalogera) • compact binary mass distribution: “fingerprints” • most evolution input parameters could be constrained with ~100 chirp mass observations • effects of r-mode instability on LMXBs (Heyl) • r-mode saturation • detection with LIGO? • EM signatures?

  7. Sources: Intermediate-Mass Black HolesMushotzky, van der Marel, Miller • observations suggest existence • formation channels: Pop III stars, cluster interactions • GWs • 10-50 M, 10s of LIGO II detections per year • > 100 M, frequency generally too low for LIGO (ringdown?)

  8. Sources: CollapseMezzacappa, Fryer • Core collapse supernovae • precision modeling of macro & micro physics is the goal • steps along the way indicate sensitivities (e.g., neutrino transport, EOS, general relativity) • multi-D simulations with multi-frequency neutrino transport don’t yet yield explosions • GW characteristics sensitive to EOS/GR (not as sensitive to neutrino transport) • new 3D SPH simulations of 15 M stars (Fryer & Warren) • GWs from bar instability detectable with LIGO II (100 cycles, 10Mpc) • GWs from proto-NS convection detectable for Galactic SNe

  9. Sources: CollapseMezzacappa, Fryer • Pop III, first generation stars • massive (no metallicity driven winds) • SPH collapse simulation of 300 M rotating star (Fryer et al.) • core rotating fast enough to develop dynamical bar instability • high redshift puts GWs from bars & BH ringing out of LIGO II range • fragmentation could be detectable with LIGO II (but does it occur?)

  10. Sources: GRBsMészáros, Norris • GWs from GRBs • long GRBs, strong association with collapse • short GRBs, binary merger? • GW and GRB emission polarized; observations with third generation detector could measure 1% polarization in a year (Kobayashi & Mészáros) • Nearby GRB/GW sources? (Norris) • class of nearby GRBs associated with Type Ic SNe? (long pulses, long lags, soft spectra, subluminous) • ex.: GRB 980425/ SN 1998bw (38 Mpc); GRB 030329 (680 Mpc) • concentrated near Supergalactic Plane; observed asymmetries • temporal separation of GRB and SNe? separate GW signatures? • could see 4 per year with LIGO II (50 Mpc, 100 cycle bar)

  11. Sources: unexpected • dark matter? • 30% of universe • couple to gravitational radiation • GW observations could determine if distribution is smooth

  12. In Summary • What information can we provide along the way to self-consistent simulations? (timing info, etc.) • Observation Informs - Finn • Is study of GWs from marginal sources worthwhile? • have “guaranteed” sources, “luxury” of studying others • often other drivers for study (SNe, GRBs, etc) • today’s marginal source can become tomorrow’s observed source (galactic supernova)

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