The WiggleZ Dark Energy Survey: testing the cosmological model with baryon acoustic oscillations at z=0.6

Abstract: We measure the imprint of baryon acoustic oscillations (BAOs) in the galaxy clustering pattern at the highest redshift achieved to date, z=0.6, using the distribution of N=132,509 emission-line galaxies in the WiggleZ Dark Energy Survey. We quantify BAOs using three statistics: the galaxy correlation function, power spectrum and the band-filtered estimator introduced by Xu et al. (2010). The results are mutually consistent, corresponding to a 4.0% measurement of the cosmic distance-redshift relation at z=0.6 (in terms of the acoustic parameter "A(z)" introduced by Eisenstein et al. (2005) we find A(z=0.6) = 0.452 +/- 0.018). Both BAOs and power spectrum shape information contribute toward these constraints. The statistical significance of the detection of the acoustic peak in the correlation function, relative to a wiggle-free model, is 3.2-sigma. The ratios of our distance measurements to those obtained using BAOs in the distribution of Luminous Red Galaxies at redshifts z=0.2 and z=0.35 are consistent with a flat Lambda Cold Dark Matter model that also provides a good fit to the pattern of observed fluctuations in the Cosmic Microwave Background (CMB) radiation. The addition of the current WiggleZ data results in a ~ 30% improvement in the measurement accuracy of a constant equation-of-state, w, using BAO data alone. Based solely on geometric BAO distance ratios, accelerating expansion (w < -1/3) is required with a probability of 99.8%, providing a consistency check of conclusions based on supernovae observations. Further improvements in cosmological constraints will result when the WiggleZ Survey dataset is complete.

• The paper confirms the BAO feature at z=0.6 at a 3.2σ significance level, constraining the acoustic parameter A(z) to 0.452±0.018.
• The paper employs galaxy correlation, power spectrum analysis, and chirped filtering methods to robustly measure BAO signals.
• The paper achieves a 30% improvement in constraining the equation-of-state parameter w, reinforcing the flat ΛCDM model and cosmic acceleration.

An Analysis of the WiggleZ Dark Energy Survey: Probing Dark Energy Using Baryon Acoustic Oscillations at Redshift z = 0.6

The paper investigates Baryon Acoustic Oscillations (BAOs) within the WiggleZ Dark Energy Survey with a focal point at redshift z = 0.6. By exploring a substantial dataset of 132,509 emission-line galaxies, the study successfully measures the imprint of BAOs in the large-scale structure of the Universe. This analysis harnesses multiple statistical methodologies, including the galaxy correlation function, the power spectrum approach, and the chirped filtering method recently conceptualized by Xu et al. (2010).

The study's findings validate the presence of the BAO feature at z = 0.6 with a notable significance level of 3.2-σ. Specifically, the consistency across these methodological approaches not only strengthens the integrity of the measurements but also allows for a nuanced understanding of the various systematic errors potentially affecting the results. Notably, the acoustic parameter, A(z = 0.6), is robustly constrained to 0.452±0.018. This result enhances the precision of evaluating the cosmic expansion and aligns well with the flat ΛCDM model, based on comparisons with BAO data from luminous red galaxies (LRGs) at z = 0.2 and z = 0.35.

Moreover, the integration of WiggleZ data enables a approximately 30% improvement in measuring the equation-of-state parameter, w, purely from BAO data. Crucially, this research highlights the probability of accelerating cosmic expansion, delineated by w < −1/3, which achieves a 99.8% certainty level, further echoing the constraints of supernovae data.

In a broader theoretical context, the study underscores that the BAO feature serves as a cosmic standard ruler, reflecting the sound horizon at the baryon drag epoch. This metric is instrumental in mapping the cosmic expansion history and allows for precise, model-independent constraints on parameters denoting dark energy. The presence of the acoustic peak in the correlation function underlines the non-interaction of non-baryonic dark matter with the relativistic plasma prior to recombination, further confirming the standard cosmological model.

The research further underscores the potential for future developments. Completion of the WiggleZ survey promises to yield even more refined cosmological constraints and progress in elucidating the nature of dark energy.

The paper contributes significantly to current cosmological research by validating previous findings regarding the cosmic structure and providing new insights into the behavior of dark energy. As the WiggleZ data expands, there is substantial promise that further detailed analysis will refine these results, improving the precision of the universal distance scale and revealing more about the enigmatic dark energy component of our Universe.