The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 10 and 11 galaxy samples (1312.4877v2)

Abstract: We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately $8\,500$ square degrees and the redshift range $0.2<z<0.7$. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance $\Lambda$CDM cosmological model, the DR11 sample covers a volume of 13\,Gpc${}^3$ and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the baryon acoustic oscillation (BAO) feature. The acoustic features are detected at a significance of over $7\,\sigma$ in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, $r_d$, which has a value of $r_{d,{\rm fid}}=149.28\,$Mpc in our fiducial cosmology. We find $D_V=(1264\pm25\,{\rm Mpc})(r_d/r_{d,{\rm fid}})$ at $z=0.32$ and $D_V=(2056\pm20\,{\rm Mpc})(r_d/r_{d,{\rm fid}})$ at $z=0.57$. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line-of-sight yields measurements at $z=0.57$ of $D_A=(1421\pm20\,{\rm Mpc})(r_d/r_{d,{\rm fid}})$ and $H=(96.8\pm3.4\,{\rm km/s/Mpc})(r_{d,{\rm fid}}/r_d)$. Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat cold dark matter model with a cosmological constant.

• The paper presents a 1% precision BAO measurement using nearly one million galaxies from SDSS-III BOSS DR10/11 data.
• It employs both the correlation function and power spectrum, achieving over 7σ significance in acoustic feature detection.
• Results validate the flat ΛCDM model and tightly constrain the cosmic distance scale and expansion history.

Baryon Acoustic Oscillations in the SDSS-III BOSS Galaxy Samples

The paper at hand presents an analysis of Baryon Acoustic Oscillations (BAO) using galaxy clustering data from the Baryon Oscillation Spectroscopic Survey (BOSS), which is a component of the Sloan Digital Sky Survey III (SDSS-III). This work focuses on Data Release 10 and 11, providing a 1% measurement of the cosmic distance scale, leveraging nearly one million galaxies covering about 8500 square degrees with redshifts between 0.2 and 0.7. These releases, particularly DR11, offer the largest volume ever surveyed at this density, amounting to a cosmic volume of 13 Gpc$^3$, allowing for a robust statistical analysis.

Key among the findings are the acoustic feature detections with over 7σ significance both in the correlation function and power spectrum. The paper concentrates on determining the distance scale through the acoustic feature relative to a fiducial cosmology-defined sound horizon. Significant measurements include $$D_V = (1264 \pm 25 \, \text{Mpc})(r_d/r_{d,\rm fid})$$ at $z = 0.32$ and $$D_V = (2056 \pm 20 \, \text{Mpc})(r_d/r_{d,\rm fid})$$ at $z = 0.57$, with a noted 1% precision. The data indicate an excellent agreement with prior CMB-based cosmological predictions, validating a flat $\Lambda$CDM cosmology with a cosmological constant.

These results have profound implications on cosmological parameters, reinforcing the $\Lambda$CDM model while providing stringent constraints on the cosmic distance scale and expansion history. The precision achieved in this paper heralds an era of precision cosmology, allowing researchers to explore with unprecedented confidence the nature of dark energy and the universe's expansion dynamics.

The implications extend to future avenues in cosmology, notably in refining models of cosmic inflation and possibly constraining extended cosmological models. The findings will be instrumental in future surveys, including those employing more extensive galaxy samples and different observational techniques, to further delineate cosmic epochs and fine-tune our understanding of the universe's large-scale structure. Considerations of systematic errors, reconstruction methodologies, and the efficacy of different clustering statistics (correlation functions vs. power spectra) are meticulously treated, ensuring that the results presented are robust, with minimized statistical and systematic uncertainties.

With these comprehensive analyses and methodologies, the BAO measurements from BOSS provide a cornerstone for cosmological parameter studies, setting a benchmark for recent and upcoming surveys aiming to probe deeper cosmic questions about the universe’s constituents and its ultimate fate.