Talk detail

Participant	Shinkai, Hisa-aki
Institution	Osaka Institute of Technology - Kitayama 1-79-1 - Osaka - Hirakata - Japan

Session	GW4	Accepted		Order	Time
Talk	Oral abstract	Title	Gravitational-wave detector using optical lattice clocks in space
Coauthors
Abstract	The new technique of measuring time by optical lattice clocks now approaches at the level of $\Delta t/t=10^{-18}$. We propose to place such precise clocks in space and to use Doppler tracking method for detecting low-frequency gravitational wave. Our plan is to locate three satellites at one A.U. distance (say at L1, L4 \& L5 of Sun-Earth orbit), and to apply reachable current technologies, then we obtain three or four order improvement ($10^{-17}$ level in $10^{-5}$Hz -- $1$ Hz) than the sensitivity of Cassini satellite in 2001. This sensitivity enables to search inspirals of inter-mediate black holes in $Gpc$ order. Based on the hierarchical growth model of black-holes in galaxies, we estimate the event rate of detections will be 20-30 for a year.
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Session	AT1	Accepted		Order	Time
Talk	Oral abstract	Title	Nonlinear Dynamics in the Einstein-Gauss-Bonnet gravity
Coauthors
Abstract	We numerically investigated how the nonlinear dynamics depends on the dimensionality and on the higher-order curvature corrections in the form of Gauss-Bonnet (GB) terms. We especially monitored the processes of appearances of a singularity (or black hole) in two models: (i) a perturbed wormhole throat in spherically symmetric space-time, and (ii) colliding scalar pulses in plane-symmetric space-time. We observed that the fate of a perturbed wormhole is either a black hole or an expanding throat depending on the total energy of the structure, and its threshold depends on the coupling constant of the GB terms ($\alpha_{\rm GB}$). We also observed that a collision of large scalar pulses will produce a large-curvature region, of which the magnitude also depends on $\alpha_{\rm GB}$. For both models, the normal corrections ($\alpha_{\rm GB}>0$) work for avoiding the appearance of singularity, although it is inevitable. We also found that in the critical situation for forming a black hole, the existence of the trapped region in the Einstein-GB gravity does not directly indicate the formation of a black hole. [PhysRevD.96.044009 (2017)]
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Session	BH2	Accepted		Order	Time
Talk	Oral abstract	Title	Autoregressive Approach to Extract Ring-down Gravitational Wave of Black-hole Merger
Coauthors
Abstract	We apply an autoregressive (AR) model for identifying the ring-down part of gravitational wave of binary black-hole mergers. This approach enables us to extract signals without templates, and is effective for short-period data. We obtain the ring-down frequency of the remnant black-hole of GW150914 as $305.94^{+18.68}_{-27.82}$ Hz (Hanford) and $300.02^{+17.49}_{-27.21}$ Hz (Livingston), and the damping frequency of it as $43.55^{+13.00}_{-17.99}$ Hz (Hanford) and $44.94^{+12.88}_{-18.30}$ Hz (Livingston). These results indicate the mass and spin of the black-hole, both of which are consistent with the values reported originally.
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