Reaffirming the Cosmic Acceleration without Supernova and CMB

TL;DR

This paper confirms cosmic acceleration using multiple independent methods without relying on supernova or CMB data, supporting the robustness of late-universe acceleration evidence.

Contribution

It extends previous null tests of cosmic acceleration by employing the PAge parameterization with diverse observational data, including BAO, lensing, and galaxy ages.

Findings

> 4σ detection of cosmic acceleration in flat and nonflat models

Tension > 3σ between curvature estimates from BAO and lensing

Supports acceleration evidence independent of supernova and CMB data

Abstract

Recent discussions about supernova magnitude evolution have raised doubts about the robustness of the late-universe acceleration. In a previous letter, Huang did a null test of the cosmic acceleration by using a Parameterization based on the cosmic Age (PAge), which covers a broad class of cosmological models including the standard $\Lambda$ cold dark matter model and its many extensions. In this work, we continue to explore the cosmic expansion history with the PAge approximation. Using baryon acoustic oscillations ({\it without} a CMB prior on the acoustic scale), gravitational strong lens time delay, and passively evolving early galaxies as cosmic chronometers, we obtain $\gtrsim 4\sigma$ detections of cosmic acceleration for both flat and nonflat PAge universes. In the nonflat case, we find a $\gtrsim 3\sigma$ tension between the spatial curvatures derived from baryon acoustic oscillations and strong lens time delay. Implications and possible systematics are discussed.