Stochastic gravitational wave and its spectral property Hyung Won Lee, Inje University 11 June, 2013 4th Japan-Korea Workshop, Osaka University

4th Japan-Korea Workshop, 10-11 June 2013 Contents Introduction Characters of stochastic GWs Sources of stochastic background of GWs Detection Remarks 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 GW Observatories 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Introduction New window onto the Universe Large scale Laser interferometer detector for Gravitational Wave(GW) LIGO, EGO-Virgo, GEO600, KAGRA LISA, ET, BBO Detecting known astrophysical sources Expect real detection around 2020 Possibly detect stochastic GW of cosmological origin A new window to study very early universe 4th Japan-Korea Workshop, 10-11 June 2013

Gravitational wave generation Triple time variation of quadruple moment Sources Man-made source (not possible to detect) Astrophysical Objects Burst from collapse Pulsar Binary system Quasinormal mode of black hole Stochastic background Cosmological background 4th Japan-Korea Workshop, 10-11 June 2013

Astrophysical Sources 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Gravitational wave Two polarization mode 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Detection of GW Large scale interferometer 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Matched filter 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Sensitivity 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Detection range 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Data Analysis GW detector is Omni-directional : all-sky search Interferometer is broad band GW is polarized : correlation measurement required Measure phase of GW Computationally intense 4th Japan-Korea Workshop, 10-11 June 2013

Characterization of stochastic backgrounds of GWs Isotropic, stationary, unpolarized Frequency spectrum is main property Energy density per unit log frequency, ℎ 0 2 Ω 𝐺𝑊 (𝑓) Spectral density of ensemble average the Fourier component of the metric, 𝑆 ℎ (𝑓) Characteristic amplitude of the stochastic background, ℎ 𝑐 (𝑓) 4th Japan-Korea Workshop, 10-11 June 2013

Energy density parameter Definition Ω 𝐺𝑊 𝑓 = 1 𝜌 𝑐 𝑑 𝜌 𝐺𝑊 𝑑 ln 𝑓 𝜌 𝑐 = 3 𝐻 0 2 8𝜋𝐺 , 𝐻 2 = 8𝜋𝐺 3 𝜌 (1st Hubble equation) 𝐻 0 = ℎ 0 ×100km/s∙Mpc, 0.5< ℎ 0 <0.65 ℎ 0 2 Ω 𝐺𝑊 (𝑓) independent of ℎ 0 Total density parameter for GW Ω 𝐺𝑊 = 0 ∞ Ω 𝐺𝑊 𝑓 𝑑 ln 𝑓 4th Japan-Korea Workshop, 10-11 June 2013

Sources of stochastic background of GWs(Allen, 1996) Inflation : Allen, et al. Cosmic String network : Vilenkin, et al. Bubbles from Phase transition : Kamionkowski, et al. Modified f(R) gravity : Capozziello, et al. Modified Chaplygyn Gas : Bouhmadi-Lopez, et al. New Idea? 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Spectrum by Inflation 4th Japan-Korea Workshop, 10-11 June 2013

Spectrum by Cosmic String 4th Japan-Korea Workshop, 10-11 June 2013

Spectrum by Bubbles from Phase tr. 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Modified f(R) gravity 4th Japan-Korea Workshop, 10-11 June 2013

Modified Chaplygin Gas 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 New Idea? Transplakian mechanism Quantum gravity effect Black body like spectrum for GWs 4th Japan-Korea Workshop, 10-11 June 2013

Detectability with Single Detector Noise spectrum Detectable if 4th Japan-Korea Workshop, 10-11 June 2013

Detection with Correlation 4th Italian-Pakistan Workshop, 15-17 Feb 2013

4th Japan-Korea Workshop, 10-11 June 2013 Sensitivity curve 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Stochastic signal From LIGO homepage 4th Japan-Korea Workshop, 10-11 June 2013

4th Japan-Korea Workshop, 10-11 June 2013 Remarks GW open a new window onto the Universe Hard to detect Specialized treatment for data Cross correlation between detectors Thermalisation like black-body radiation? Model dependent We need to see real GW data 4th Japan-Korea Workshop, 10-11 June 2013