Tatsuya Narikawa

Constraint on the cosmological f (R) model from the multipole power spectrum of the SDSS luminous red galaxy sample and prospects for a future redshift survey

A constraint on the viable

Testing general scalar-tensor gravity and massive gravity with cluster lensing

f(R)

Testing gravity with halo density profiles observed through gravitational lensing

model is investigated by confronting theoretical predictions with the multipole power spectrum of the luminous red galaxy sample of the Sloan Digital Sky Survey, data release 7. We obtain a constraint on the Compton wavelength parameter of the

Detectability of bigravity with graviton oscillations using gravitational wave observations

f(R)

HALO MODELS IN MODIFIED GRAVITY THEORIES WITH SELF-ACCELERATED EXPANSION

model on the scales of cosmological large-scale structure. A prospect of constraining the Compton wavelength parameter with a future redshift survey is also investigated. The usefulness of the redshift-space distortion for testing the gravity theory on cosmological scales is demonstrated.

Optimal follow-up observations of gravitational wave events with small optical telescopes

We explore the possibility of testing modified gravity exhibiting the Vainshtein mechanism against observations of cluster lensing. We work in the most general scalar-tensor theory with second-order field equations (Horndeskis theory), and derive static and spherically symmetric solutions, for which the scalar field is screened below a certain radius. It is found that the essential structure of the problem in the most general case can be captured by the program of classifying Vainshtein solutions out of different solutions to a quintic equation, as has been performed in the context of massive gravity. The key effect on gravitational lensing is that the second derivative of the scalar field can substantially be large at the transition from screened to unscreened regions, leaving a dip in the convergence. This allows us to put observational constraints on parameters characterizing the general scalar-tensor modification of gravity. We demonstrate how this occurs in massive gravity as an example, and discuss its observational signatures in cluster lensing.

The potential of advanced ground-based gravitational wave detectors to detect generic deviations from general relativity

We present a new test of the modified gravity endowed with the Vainshtein mechanism with the density profile of a galaxy cluster halo observed through gravitational lensing. A scalar degree of freedom in the galileon modified gravity is screened by the Vainshtein mechanism to recover Newtonian gravity in high-density regions, however it might not be completely hidden on the outer side of a cluster of galaxies. Then the modified gravity might yield an observational signature in a surface mass density of a cluster of galaxies measured through gravitational lensing, since the scalar field could contribute to the lensing potential. We investigate how the transition in the Vainshtein mechanism affects the surface mass density observed through gravitational lensing, assuming that the density profile of a cluster of galaxies follows the original Navarro-Frenk-White (NFW) profile, the generalized NFW profile and the Einasto profile. We compare the theoretical predictions with observational results of the surface mass density reported recently by other researchers. We obtain constraints on the amplitude and the typical scale of the transition in the Vainshtein mechanism in a subclass of the generalized galileon model.

Characterising linear growth rate of cosmological density perturbations in f(R) model

The gravitational waveforms in the ghost-free bigravity theory exhibit deviations from those in general relativity. The main difference is caused by graviton oscillations in the bigravity theory. We investigate the prospects for the detection of the corrections to gravitational waveforms from coalescing compact binaries due to graviton oscillations and for constraining bigravity parameters with the gravitational wave observations. We consider the bigravity model discussed by the De Felice-Nakamura-Tanaka subset of the bigravity model, and the phenomenological model in which the bigravity parameters are treated as independent variables. In both models, the bigravity waveform shows strong amplitude modulation, and there can be a characteristic frequency of the largest peak of the amplitude, which depends on the bigravity parameters. We show that there is a detectable region of the bigravity parameters for the advanced ground-based laser interferometers, such as Advanced LIGO, Advanced Virgo, and KAGRA. This region corresponds to the effective graviton mass of

Erratum: Characterizing the linear growth rate of cosmological density perturbations in an f(R) model [Phys. Rev. D 81, 043528 (2010)]

\mu \geq 10^{-17}~{\rm cm}^{-1}

Development of KAGRA Algorithmic Library (KAGALI)

for