Affiliation:
1. Instituto de Física, Universidade Federal do Rio Grande do Sul , Av. Bento Gonçalves 9500, Porto Alegre, R.S. 90040-060, Brazil
2. Shanghai Astronomical Observatory, Chinese Academy of Sciences , 80 Nandan Rd., Shanghai 200030, China
Abstract
ABSTRACT
General Relativity (GR) has been successfully tested mainly at Solar system scales; however, galaxy-scale tests have become popular in the last few decades. In this work, we investigate the ηPPN parameter, which is commonly defined by the ratio of two scalar potentials that appears in the cosmological linearly perturbed metric. Under the assumption of GR and a vanish anisotropic stress tensor, ηPPN = 1. Using ALMA, HST, and VLT/MUSE data, we combine mass measurements, using gravitational lensing and galactic dynamics, for the SDP.81 lens galaxy (z = 0.299) to constrain ηPPN. By using a flexible and self-consistent mass profile, our fiducial model takes into account the contribution of the stellar mass and a dark matter halo to reconstruct the lensed galaxy and the spatially resolved stellar kinematics. We infer, after accounting for systematic uncertainties related to the mass model, cosmology, and kinematics, $\eta _{\text{PPN}} = 1.13^{+0.03}_{-0.03}\pm 0.20\, (\text{sys})$, which is in accordance with GR predictions. Better spectroscopy data are needed to push the systematics down and bring the uncertainty to the percentage level since our analysis shows that the main source of the systematics is related to kinematics, which heavily depends on the signal-to-noise ratio of the spectra.
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics