beecee Posted April 23, 2021 Posted April 23, 2021 https://phys.org/news/2021-04-scientists-dark-energy.html Scientists make further step towards understanding dark energy: The extended Baryon Oscillation Spectroscopic Survey (eBOSS) collaboration has released its latest scientific results. These results include two studies on dark energy led by Prof. Zhao Gongbo and Prof. Wang Yuting, respectively, from National Astronomical Observatories of the Chinese Academy of Sciences (NAOC). The study led by Prof. Zhao was recently published in Monthly Notices of the Royal Astronomical Society. Based on eBOSS observations, Prof. Zhao's team measured the history of cosmic expansion and structure growth in a huge volume of the past universe, corresponding to a distance range between 0.7 and 1.8 billion light years away from us. This volume had never been probed before. This study took advantage of a method called "multi-tracer analysis," which mitigated the observational systematics proposed and implemented by Prof. Zhao and Prof. Wang. more at link...... the paper: https://academic.oup.com/mnras/article-abstract/504/1/33/6185048?redirectedFrom=fulltext The completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: a multitracer analysis in Fourier space for measuring the cosmic structure growth and expansion rate: ABSTRACT: We perform a joint BAO and RSD analysis using the eBOSS DR16 LRG and ELG samples in the redshift range of z ∈ [0.6, 1.1], and detect an RSD signal from the cross-power spectrum at a ∼4σ confidence level, i.e., fσ8 = 0.317 ± 0.080 at zeff = 0.77. Based on the chained power spectrum, which is a new development in this work to mitigate the angular systematics, we measure the BAO distances and growth rate simultaneously at two effective redshifts, namely, DM/rd (z = 0.70) = 17.96 ± 0.51, DH/rd (z = 0.70) = 21.22 ± 1.20, fσ8 (z = 0.70) = 0.43 ± 0.05, and DM/rd (z = 0.845) = 18.90 ± 0.78, DH/rd (z = 0.845) = 20.91 ± 2.86, fσ8 (z = 0.845) = 0.30 ± 0.08. Combined with BAO measurements including those from the eBOSS DR16 QSO and Lyman-α sample, our measurement has raised the significance level of a non-zero ΩΛ to ∼11σ. The data product of this work is publicly available at https://github.com/icosmology/eBOSS_DR16_LRGxELG and https://www.sdss.org/science/final-bao-and-rsd-measurements/.
Recommended Posts