标题：The VIMOS Public Extragalactic Redshift Survey (VIPERS) - Gravity test from the combination of redshift-space distortions and galaxy-galaxy lensing at 0.5 < z < 1.2
其他标题：Gravity test from the combination of redshift-space distortions and galaxy-galaxy lensing at 0.5 < z < 1.2⋆
摘要：We carry out a joint analysis of redshift-space distortions and galaxy-galaxy lensing, with the aim of measuring the growth rate of structure; this is a key quantity for understanding the nature of gravity on cosmological scales and late-time cosmic acceleration. We make use of the final VIPERS redshift survey dataset, which maps a portion of the Universe at a redshift ofz≃ 0.8, and the lensing data from the CFHTLenS survey over the same area of the sky. We build a consistent theoretical model that combines non-linear galaxy biasing and redshift-space distortion models, and confront it with observations. The two probes are combined in a Bayesian maximum likelihood analysis to determine the growth rate of structure at two redshiftsz= 0.6andz= 0.86. We obtain measurements offσ8(0.6) = 0.48 ± 0.12andfσ8(0.86) = 0.48 ± 0.10. The additional galaxy-galaxy lensing constraint alleviates galaxy bias andσ8degeneracies, providing direct measurements offandσ8:[f(0.6),σ8(0.6)] = [0.93 ± 0.22,0.52 ± 0.06]and[f(0.86),σ8(0.86)] = [0.99 ± 0.19,0.48 ± 0.04]. These measurements are statistically consistent with a Universe where the gravitational interactions can be described by General Relativity, although they are not yet accurate enough to rule out some commonly considered alternatives. Finally, as a complementary test we measure the gravitational slip parameter,EG, for the first time atz> 0.6. We find values ofE̅G(0.6) = 0.16±0.09 andE̅G(0.86) = 0.09±0.07, whenEGis averaged over scales above3h-1Mpc. We find that ourEGmeasurements exhibit slightly lower values than expected for standard relativistic gravity in aΛCDMbackground, although the results are consistent within1−2σ.
关键词：enlarge-scale structure of Universecosmology: observationscosmological parametersdark energygalaxies: high-redshift
