Redshift drift exploration for interacting dark energy

Jia-Jia Geng,Yun-He Li,Xin Zhang,Jing-Fei Zhang

doi:10.1140/epjc/s10052-015-3581-8

Jia-Jia Geng, Yun-He Li + Show 2 more

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https://doi.org/10.1140/epjc/s10052-015-3581-8

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Abstract

By detecting redshift drift in the spectra of the Lyman-\(\alpha \) forest of distant quasars, the Sandage–Loeb (SL) test directly measures the expansion of the universe, covering the “redshift desert” of \(2 \lesssim z \lesssim 5\). Thus this method is definitely an important supplement to the other geometric measurements and will play a crucial role in cosmological constraints. In this paper, we quantify the ability of the SL test signal by a CODEX-like spectrograph for constraining interacting dark energy. Four typical interacting dark energy models are considered: (i) \(Q=\gamma H\rho _c\), (ii) \(Q=\gamma H\rho _{de}\), (iii) \(Q=\gamma H_0\rho _c\), and (iv) \(Q=\gamma H_0\rho _{de}\). The results show that for all the considered interacting dark energy models, relative to the current joint SN \(+\) BAO \(+\) CMB \(+\) \(H_0\) observations, the constraints on \(\Omega _m\) and \(H_0\) would be improved by about 60 and 30–40 %, while the constraints on w and \(\gamma \) would be slightly improved, with a 30-year observation of the SL test. We also explore the impact of the SL test on future joint geometric observations. In this analysis, we take the model with \(Q=\gamma H\rho _c\) as an example, and we simulate future SN and BAO data based on the space-based project WFIRST. We find that with the future geometric constraints, the redshift drift observations would help break the geometric degeneracies in a meaningful way, thus the measurement precisions of \(\Omega _m\), \(H_0\), w, and \(\gamma \) could be substantially improved using future probes.

Highlights

As a purely geometric measurement, the Sandage–Loeb (SL) test will be crucial to probe the “redshift desert” (2 z 5) by directly measuring the expansion of the universe
In this work, we only consider to use the geometric measurements to constrain the interacting dark energy models; in particular, we focus on the future redshift drift data
As pointed out in Ref. [14], only about 30 quasars are bright enough or lying at high enough redshift for actual observation, based on a Monte Carlo simulation using a telescope with a spectrograph like CODEX

Summary

Introduction

As a purely geometric measurement, the Sandage–Loeb (SL) test will be crucial to probe the “redshift desert” (2 z 5) by directly measuring the expansion of the universe It was firstly proposed by Sandage [3] to directly measure the variation of redshift of distant sources. [14], only about 30 quasars are bright enough or lying at high enough redshift for actual observation, based on a Monte Carlo simulation using a telescope with a spectrograph like CODEX. As far as we know, in most existing papers, the best-fit CDM model to the current data is chosen as the fiducial model, based on which SL test data are simulated. When these SL test data are further combined with other actual data to constrain dark energy models, tension between the simulated SL data and

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