Testing general relativity on cosmological scales at redshift z ∼ 1.5 with quasar and CMB lensing
Abstract
We test general relativity (GR) at the effective redshift $\bar{z} \sim 1.5$ by estimating the statistic E_{G}, a probe of gravity, on cosmological scales $19  190\, h^{1}{\rm Mpc}$. This is the highest redshift and largest scale estimation of E_{G} so far. We use the quasar sample with redshifts 0.8 < z < 2.2 from Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey Data Release 16 as the largescale structure (LSS) tracer, for which the angular power spectrum $C_\ell ^{qq}$ and the redshiftspace distortion parameter β are estimated. By crosscorrelating with the Planck 2018 cosmic microwave background (CMB) lensing map, we detect the angular crosspower spectrum $C_\ell ^{\kappa q}$ signal at $12\, \sigma$ significance. Both jackknife resampling and simulations are used to estimate the covariance matrix (CM) of E_{G} at five bins covering different scales, with the later preferred for its better constraints on the covariances. We find E_{G} estimates agree with the GR prediction at $1\, \sigma$ level over all these scales. With the CM estimated with 300 simulations, we report a bestfitting scaleaveraged estimate of $E_G(\bar{z})=0.30\pm 0.05$, which is in line with the GR prediction $E_G^{\rm GR}(\bar{z})=0.33$ with Planck 2018 CMB + BAO matter density fraction Ω_{m} = 0.31. The statistical errors of E_{G} with future LSS surveys at similar redshifts will be reduced by an order of magnitude, which makes it possible to constrain modified gravity models.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 February 2021
 DOI:
 10.1093/mnras/staa3672
 arXiv:
 arXiv:2007.12607
 Bibcode:
 2021MNRAS.501.1013Z
 Keywords:

 gravitation;
 gravitational lensing: weak;
 cosmic background radiation;
 largescale structure of Universe;
 cosmology: observations;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 16 pages, 14 figures