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The effect of our local motion on the Sandage-Loeb test of the cosmic expansion
Takuya Inoue, Eiichiro Komatsu, Wako Aoki +3
Redshifts of an astronomical body measured at multiple epochs (e.g., separated by 10 years) are different due to the cosmic expansion. This so-called Sandage-Loeb test offers a dir…
Probing the Universe through the Stochastic Gravitational Wave Background
Sachiko Kuroyanagi, Takeshi Chiba, Tomo Takahashi
Stochastic gravitational wave backgrounds, predicted in many models of the early universe and also generated by various astrophysical processes, are a powerful probe of the Univers…
Cosmological constraints on scalar-tensor gravity and the variation of the gravitational constant
Junpei Ooba, Kiyotomo Ichiki, Takeshi Chiba +1
We present cosmological constraints on the scalar-tensor theory of gravity by analyzing the angular power spectrum data of the cosmic microwave background obtained from the Planck…
Planck constraints on scalar-tensor cosmology and the variation of the gravitational constant
Junpei Ooba, Kiyotomo Ichiki, Takeshi Chiba +1
Cosmological constraints on the scalar-tensor theory of gravity by analyzing the angular power spectrum data of the cosmic microwave background (CMB) obtained from the Planck 2015…
Reconstructing the inflaton potential from the spectral index
Takeshi Chiba
Recent cosmological observations are in good agreement with the scalar spectral index with , where is the number of e-foldings. Quadratic chaotic model, S…
Consistency Relations for Large Field Inflation: Non-minimal Coupling
Takeshi Chiba, Kazunori Kohri
We derive the consistency relations for a chaotic inflation model with a non-minimal coupling to gravity. For a quadratic potential in the limit of a small non-minimal coupling par…
Consistency Relations for Large Field Inflation
Takeshi Chiba, Kazunori Kohri
Consistency relations for chaotic inflation with a monomial potential and natural inflation and hilltop inflation are given which involve the scalar spectral index , the tenso…
Implications of the B-mode Polarization Measurement for Direct Detection of Inflationary Gravitational Waves
Sachiko Kuroyanagi, Shinji Tsujikawa, Takeshi Chiba +1
The prospects for direct measurements of inflationary gravitational waves by next generation interferometric detectors inferred from the possible detection of B-mode polarization o…
Observational Constraints on Quintessence: Thawing, Tracker, and Scaling models
Takeshi Chiba, Antonio De Felice, Shinji Tsujikawa
For two types of quintessence models having thawing and tracking properties, there exist analytic solutions for the dark energy equation of state w expressed in terms of several fr…
LBQS 0103-2753: A Binary Quasar in a Major Merger
G. A. Shields, D. J. Rosario, V. Junkkarinen +3
We present HST and UKIRT spectra and images of the 2 kpc binary quasar LBQS 0103-2753 (z=0.858). The HST images (V- and I-band) show tidal features demonstrating that this system i…
Runaway Domain Wall and Space-time Varying alpha
Takeshi Chiba, Masahide Yamaguchi
Recently spatial as well as temporal variations of the fine structure constant alpha have been reported. We show that a "runaway domain wall", which arises for the scalar field pot…
Prospects for Direct Detection of Inflationary Gravitational Waves by Next Generation Interferometric Detectors
Sachiko Kuroyanagi, Takeshi Chiba, Naoshi Sugiyama
We study the potential impact of detecting the inflationary gravitational wave background by the future space-based gravitational wave detectors, such as DECIGO and BBO. The signal…
Slow-roll Extended Quintessence
Takeshi Chiba, Masaru Siino, Masahide Yamaguchi
We derive the slow-roll conditions for a non-minimally coupled scalar field (extended quintessence) during the radiation/matter dominated era extending our previous results for tha…
Gravitational Waves from Q-ball Formation
Takeshi Chiba, Kohei Kamada, Masahide Yamaguchi
We study the detectability of the gravitational waves (GWs) from the Q-ball formation associated with the Affleck-Dine (AD) mechanism, taking into account both of the dilution effe…
The Equation of State of Tracker Fields
Takeshi Chiba
We derive the equation of state of tracker fields, which are typical examples of freezing quintessence (quintessence with the equation of state approaching toward -1), taking into…
Slow-roll k-essence
Takeshi Chiba, Sourish Dutta, Robert J. Scherrer
We derive slow-roll conditions for thawing k-essence with a separable Lagrangian . We examine the evolution of the equation of state parameter, , as a function…
Slow-Roll Thawing Quintessence
Takeshi Chiba
We derive slow-roll conditions for thawing quintessence. We solve the equation of motion of for a Taylor expanded potential (up to the quadratic order) in the limit where the e…