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1. chinaXiv:201709.00130 [pdf]

Constraints on the DGP Model from Recent Supernova Observations and Baryon Acoustic Oscillations

Zong-Kuan Guo , Zong-Hong Zhu , J.S. Alcaniz , Yuan-Zhong Zhang; Zong-Hong Zhu; J.S. Alcaniz; Yuan-Zhong Zhang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Although there is mounting observational evidence that the expansion of our universe is undergoing a late-time acceleration, the mechanism for this acceleration is yet unknown. In the so-called Dvali-Gabadadze-Porrati (DGP) model this phenomena is attributed to gravitational leakage into extra dimensions. In this work, we mainly focus our attention to the constraints on the model from the gold sample of type Ia supernovae (SNeIa), the first year data from the Supernova Legacy Survey (SNLS) and the baryon acoustic oscillation (BAO) peak found in the Sloan Digital Sky Survey (SDSS). At 99.73% confidence level, the combination of the three databases provides m = 0.270+0.018?0.017 and rc = 0.216+0.012?0.013 (hence a spatially closed universe with k = ?0.350+0.080?0.083), which seems to be in contradiction with the most recent WMAP results indicating a flat universe. Based on this result, we also estimated the transition redshift (at which the universe switches from deceleration to acceleration) to be 0.70 < zq=0 < 1.01, at 2#27;confidence level.

submitted time 2017-09-27 Hits1522Downloads755 Comment 0

2. chinaXiv:201608.00197 [pdf]

Testing Einstein's Equivalence Principle With Gravitational Waves

Xue-Feng Wu; He Gao; Jun-Jie Wei; Xi-Long Fan; Peter M?esz?aros; Bing Zhang; Zi-Gao Dai; Shuang-Nan Zhang; Zong-Hong Zhu
Subjects: Physics >> Nuclear Physics

A conservative constraint on the Einstein Equivalence Principle (EEP) can be obtained under the assumption that the observed time delay between correlated particles from astronomical sources is dominated by the gravitational fields through which they move. Current limits on the EEP are mainly based on the observed time delays of photons with different energies, and it is highly desirable to develop more accurate tests involving different types of particles. The detection by the advanced LIGO/VIRGO systems of gravitational waves (GWs) will provide attractive candidates for constraining the EEP, which would further extend the tested particle species to the gravitons, with potentially higher accuracy. Considering the capabilities of the advanced LIGO/VIRGO network and the source direction uncertainty, we show that the joint detection of GWs and electromagnetic signals can potentially probe the EEP to an accuracy of 10?11, which is several orders of magnitude tighter than previous limits.

submitted time 2016-08-30 Hits983Downloads583 Comment 0

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