The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: measurement of the BAO and growth rate of structure of the emission line galaxy sample from the anisotropic power spectrum between redshift 0.6 and 1.1 (2007.09008v3)

Abstract: We analyse the large-scale clustering in Fourier space of emission line galaxies (ELG) from the Data Release 16 of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey. The ELG sample contains 173,736 galaxies covering 1,170 square degrees in the redshift range $0.6 < z < 1.1$. We perform a BAO measurement from the post-reconstruction power spectrum monopole, and study redshift space distortions (RSD) in the first three even multipoles. Photometric variations yield fluctuations of both the angular and radial survey selection functions. Those are directly inferred from data, imposing integral constraints which we model consistently. The full data set has only a weak preference for a BAO feature ($1.4\sigma$). At the effective redshift $z_{\rm eff} = 0.845$ we measure $D_{\rm V}(z_{\rm eff})/r_{\rm drag} = 18.33_{-0.62}^{+0.57}$, with $D_{\rm V}$ the volume-averaged distance and $r_{\rm drag}$ the comoving sound horizon at the drag epoch. In combination with the RSD measurement, at $z_{\rm eff} = 0.85$ we find $f\sigma_8(z_{\rm eff}) = 0.289_{-0.096}^{+0.085}$, with $f$ the growth rate of structure and $\sigma_8$ the normalisation of the linear power spectrum, $D_{\rm H}(z_{\rm eff})/r_{\rm drag} = 20.0_{-2.2}^{+2.4}$ and $D_{\rm M}(z_{\rm eff})/r_{\rm drag} = 19.17 \pm 0.99$ with $D_{\rm H}$ and $D_{\rm M}$ the Hubble and comoving angular distances, respectively. These results are in agreement with those obtained in configuration space, thus allowing a consensus measurement of $f\sigma_8(z_{\rm eff}) = 0.315 \pm 0.095$, $D_{\rm H}(z_{\rm eff})/r_{\rm drag} = 19.6_{-2.1}^{+2.2}$ and $D_{\rm M}(z_{\rm eff})/r_{\rm drag} = 19.5 \pm 1.0$. This measurement is consistent with a flat $\Lambda$CDM model with Planck parameters.

Analysis of the SDSS-IV eBOSS ELG BAO and RSD Measurements

In the presented paper, the authors delve into the analysis of the Baryon Acoustic Oscillation (BAO) and redshift space distortion (RSD) measurements using the emission line galaxy (ELG) sample from the Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS), as provided in Data Release 16. Their paper covers a redshift range from 0.6 to 1.1, encompassing a substantial sample of 173,736 galaxies spread over 1,170 square degrees. This investigation is composed of two primary focal points: the measurement of the BAO feature and the assessment of the growth rate of structure through RSD analyses.

The BAO analysis was conducted using the power spectrum monopole post-reconstruction. Although the full dataset exhibited only a weak preference for a BAO feature with a significance of $1.4\sigma$, the researchers were able to produce notable measurements, including a volume-averaged distance of $$D_{\rm V}(z_{\rm eff})/r_{\rm drag} = 18.33_{-0.62}^{+0.57}$$ at the effective redshift $z_{\rm eff} = 0.845$. This result signifies consistency with a flat $\Lambda$CDM model configured with Planck parameters.

On the RSD front, the analysis involved the first three even multipoles of the pre-reconstruction power spectrum, yielding $f\sigma_8(z_{\rm eff}) = 0.289_{-0.096}^{+0.085}$. These measurements were consistent with those obtained in configuration space analyses. The authors further present combined results from both BAO and RSD data: $f\sigma_8(z_{\rm eff}) = 0.315 \pm 0.095$, $$D_{\rm H}(z_{\rm eff})/r_{\rm drag} = 19.6_{-2.1}^{+2.2}$$, and $D_{\rm M}(z_{\rm eff})/r_{\rm drag} = 19.5 \pm 1.0$.

The implications of these findings are significant from both theoretical and practical standpoints. The corroboration with the $\Lambda$CDM model lends further support to the prevailing cosmological paradigm, reinforcing the framework within which dark energy is perceived to drive the accelerated expansion of the universe. The results from this paper not only complement earlier findings but also provide refined constraints that could guide future investigations.

Future developments are anticipated to extend these analyses, aiming to reduce the uncertainties inherent in such measurements, particularly through more comprehensive datasets acquired from next-generation spectroscopic surveys. These efforts would further refine our understanding of the large-scale structure of the universe, probing into the intricate details of RSD and BAO signatures at various cosmic epochs.