The Astrophysics of Gravitational Wave SourcesThe Astrophysics of Gravitational Wave Sources

Conference Summary:

Ground-Based Detectors(1-104 Hz)

Kimberly New, LANL

Detection & Data Analysis: Detection & Data Analysis: LIGO & GEO’s science runsLIGO & GEO’s science runs

Brady & MavalvalaBrady & Mavalvala

• high sensitivity, large bandwidth, hours of coincident operation

• searches– NS/NS chirps, bursts, known pulsars, stochastic bkgd.

• techniques used

• science implications

Detection & Data Analysis: Detection & Data Analysis: Detectors in 2012Detectors in 2012

FinnFinn

• 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

Detection & Data Analysis: Detection & Data Analysis: Detectors in 2012Detectors in 2012

FinnFinn

• 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)

Sources: Sources: BinariesBinariesSchutz, Centrella, Bulik, HeylSchutz, 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

Sources: Sources: BinariesBinariesSchutz, Centrella, Bulik, HeylSchutz, 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?

Sources: Sources: Intermediate-Mass Black HolesIntermediate-Mass Black HolesMushotzky, van der Marel, MillerMushotzky, 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?)

Sources: Sources: CollapseCollapseMezzacappa, FryerMezzacappa, 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

Sources: Sources: CollapseCollapseMezzacappa, FryerMezzacappa, 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?)

Sources: Sources: GRBsGRBsMMészáros, Norrisészáros, 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)

Sources: Sources: unexpectedunexpected

– dark matter?• 30% of universe

• couple to gravitational radiation

• GW observations could determine if distribution is smooth

In SummaryIn 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)