English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Einstein's theory of general relativity (GR) has been precisely tested onsolar system scales, but extragalactic tests are still poorly performed. Inthis work, we use a newly compiled sample of galaxy-scale strong gravitationallenses to test the validity of GR on kiloparsec scales. In order to solve thecircularity problem caused by the preassumption of a specific cosmologicalmodel based on GR, we employ the distance sum rule in theFriedmann-Lema\^{\i}tre-Robertson-Walker metric to directly estimate theparameterized post-Newtonian (PPN) parameter $\gamma_{\rm PPN}$ and the cosmiccurvature $\Omega_k$ by combining observations of strong lensing and Type Iasupernovae. This is the first simultaneous measurement of $\gamma_{\rm PPN}$and $\Omega_k$ without any assumptions about the contents of the universe orthe theory of gravity. Our results show that $\gamma_{\rmPPN}=1.11^{+0.11}_{-0.09}$ and $\Omega_{k}=0.48^{+1.09}_{-0.71}$, indicating astrong degeneracy between the two quantities. The measured $\gamma_{\rm PPN}$,which is consistent with the prediction of 1 from GR, provides a preciseextragalactic test of GR with a fractional accuracy better than 9.0\%. If aprior of the spatial flatness (i.e., $\Omega_{k}=0$) is adopted, the PPNparameter constraint can be further improved to $\gamma_{\rmPPN}=1.07^{+0.07}_{-0.07}$, representing a precision of 6.5\%. On the otherhand, in the framework of GR (i.e., $\gamma_{\rm PPN}=1$), our results arestill marginally compatible with zero curvature($\Omega_k=-0.12^{+0.48}_{-0.36}$), supporting no significant deviation from aflat universe.

Direct Estimate of the Post-Newtonian Parameter and Cosmic Curvature from Galaxy-scale Strong Gravitational Lensing