The power spectrum of primordial tensor perturbations Pt increases rapidly in the high frequency region if the spectral index nt 〉 0. It is shown that the amplitude of relic gravitational waves ht （5×109 Hz） varies from 10-36 to 10-25 while rtt varies from -6.25 × 10-3 to 0.87. A high frequency gravitational wave detector proposed by F,-Y, Li detects gravitational waves through observing the perturbed photon flux that is generated by interaction between relic gravitational waves and electromagnetic field. It is shown that the perturbative photon flux N1x （5 × 109 Hz） varies from 1.40× 10-4 s-i to 2.85× 107 s-i while nt varies from -6.25 ×10-3 to 0.87, Correspondingly, the ratio of the transverse perturbative photon flux N1x to the background photon flux varies from 10-28 to 10-16.
Even though the Hubble constant cannot be significantly determined just by the low-redshift Baryon Acoustic Oscillation(BAO)data, it can be tightly constrained once the high-redshift BAO data are combined. We combined BAO data from 6d FGS, BOSS DR11 clustering of galaxies, Wiggle Z and z = 2.34 from BOSS DR11 quasar Lyman-α forest lines to get H0= 68.17+1.55-1.56 km s-1Mpc-1. In addition, we adopted the simultaneous measurements of H(z) and DA(z) from the two-dimensional two-point correlation function from BOSS DR9 CMASS sample and two-dimensional matter power spectrum from SDSS DR7 sample to obtain H0=(68.11±1.69) km s-1Mpc-1. Finally, combining all of the BAO datasets, we conclude that H0=(68.11±0.86) km s-1Mpc-1, a1.3% determination.
In this work, we explore the cosmological implications of different baryon acoustic oscillation （BAO） data, including the BAO data extracted by using the spherically averaged one-dimensional galaxy clustering （GC） statistics （hereafter BAO 1） and the BAO data obtained by using the anisotropic two-dimensional GC statistics （hereafter BAO2）. To make a comparison, we also take into account the case without BAO data （hereafter NO BAO）. Firstly, making use of these BAO data, as well as the SNLS3 type la supernovae sample and the Planck distance priors data, we give the cosmological constraints of the ACDM, the wCDM, and the Chevallier-Polarski-Linder （CPL） model. Then, we discuss the impacts of different BAO data on cosmological consquences, including its effects on parameter space, equation of state （EoS）, figure of merit （FoM）, deceleration-acceleration transition redshift, Hubble parameter H（z）, deceleration parameter q（z）, statefinder hierarchy S3^（1）（z）, S4^（1）（z） and cosmic age t（z）. We find that： （1） NO BAO data always give a smallest fractional matter density Ωm0, a largest fractional curvature density Ωk0 and a largest Hubble constant h; in contrast, BAO1 data always give a largest Ωm0, a smallest Ωk0 and a smallest h. （2） For the wCDM and the CPL model, NO BAO data always give a largest EoS w; in contrast, BA02 data always give a smallest w. （3） Compared with the case of BAO1, BAO2 data always give a slightly larger FoM, and thus can give a cosmological constraint with a slightly better accuracy. （4） The impacts of different BAO data on the cosmic evolution and the comic age are very small, and cannot be distinguished by using various dark energy diagnoses and the cosmic age data.
In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation（LIV）. As the most energetic explosions in the Universe, gamma-ray bursts（GRBs） provide an effect way to probe quantum gravity effects. In this paper, we use the continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale MQG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to low energy ones. Based on the fact that the LIV-induced time delay cannot be longer than the duration of a GRB,we present the most conservative estimate of the quantum gravity energy scales from 20 short GRBs. The strictest constraint, M_（QG） 〉 5.05 × 10^（14） GeV in the linearly corrected case, is from GRB 140622 A. Our constraint on MQG,although not as tight as previous results, is the safest and most reliable so far.
Recently Background Imaging of Cosmic Extragalactic Polarization （B2） discovered the relic gravitational waves at 7.00- confi- dence level. However, the other cosmic microwave background （CMB） data, for example Planck data released in 2013 （P13）, prefer a much smaller amplitude of the primordial gravitational waves spectrum if a power-law spectrum of adiabatic scalar perturbations is assumed in the six-parameter ACDM cosmology. In this paper, we explore whether the wCDM model and the running spectral index can relax the tension between B2 and other CMB data. Specifically we found that a positive running of running of spectral index is preferred at 1.70- level from the combination of B2, P 13 and WMAP Polarization data.
We investigate a second order parabolic parametrization, w（a） = wt ＋ wa（at - a）2, which is a direct characterization of a possible turning in w. The cosmological consequence of this parametrization is explored by using the observational data of the SNLS3 type Ia supernovae sample, the CMB measurements from WMAP9 and Planck, the Hubble parameter measurement from HST, and the baryon acoustic oscillation （BAO） measurements from 6dFGS, BOSS DRI 1 and improved WiggleZ. We found the existence of a turning point in w at a - 0.7 is favored at 10- CL. In the epoch 0.55 〈 a 〈 0.9, w 〈 -1 is favored at 10- CL, and this significance increases near a - 0.8, reaching a 20- CL. The parabolic parametrization achieve equivalent performance to the ACDM and Chevallier-Polarski-Linder （CPL） models when the Akaike information criterion was used to assess them. Our analysis shows the value of considering high order parametrizations when studying the cosmological constraints on w.
The neutrino oscillations imply that at least two neutrinos have non-zero masses[1].However,up to now,we only measure the differences of neutrino mass squares in a standard scenario with three massive eigenstates[2],i.e.
In this paper we propose a new inflation model named( p, q) inflation model in which the inflaton potential contains both positive and negative powers of inflaton field in the polynomial form. We derive the accurate predictions of the canonical single-field slow-roll inflation model. Using these formula, we show that our inflation model can easily generate a large amplitude of tensor perturbation and a negative running of spectral index with large absolute value.
