Here, we use flux-transmission correlations in Lyα forests to measure the imprint of baryon acoustic oscillations (BAO). The study uses spectra of 157,783 quasars in the redshift range 2.1 ≤ z ≤ 3.5 ...from the Sloan Digital Sky Survey (SDSS) Data Release 12 (DR12). Besides the statistical improvements on our previous studies using SDSS DR9 and DR11, we have implemented numerous improvements in the analysis procedure, allowing us to construct a physical model of the correlation function and to investigate potential systematic errors in the determination of the BAO peak position. The Hubble distance, DH = c/H(z), relative to the sound horizon is DH(z = 2.33)/rd = 9.07 ± 0.31. The best-determined combination of comoving angular-diameter distance, DM, and the Hubble distance is found to be D0.7HD0.3M/rd = 13.94 ± 0.35. This value is 1.028 ± 0.026 times the prediction of the flat- ΛCDM model consistent with the cosmic microwave background (CMB) anisotropy spectrum. The errors include marginalization over the effects of unidentified high-density absorption systems and fluctuations in ultraviolet ionizing radiation. Independently of the CMB measurements, the combination of our results and other BAO observations determine the open-ΛCDM density parameters to be ΩM = 0.296 ± 0.029, ΩΛ = 0.699 ± 0.100 and Ωk = –0.002 ± 0.119.
We present constraints on masses of active and sterile neutrinos. We use the one-dimensional Ly\(\alpha\)-forest power spectrum from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan ...Digital Sky Survey (SDSS-III) and from the VLT/XSHOOTER legacy survey (XQ-100). In this paper, we present our own measurement of the power spectrum with the publicly released XQ-100 quasar spectra. Fitting Ly\(\alpha\) data alone leads to cosmological parameters in excellent agreement with the values derived independently from Planck 2015 Cosmic Microwave Background (CMB) data. Combining BOSS and XQ-100 Ly\(\alpha\) power spectra, we constrain the sum of neutrino masses to \(\sum m_\nu < 0.8\) eV (95\% C.L). With the addition of CMB data, this bound is tightened to \(\sum m_\nu < 0.14\) eV (95\% C.L.). With their sensitivity to small scales, Ly\(\alpha\) data are ideal to constrain \(\Lambda\)WDM models. Using XQ-100 alone, we issue lower bounds on pure dark matter particles: \(m_X \gtrsim 2.08 \: \rm{keV}\) (95\% C.L.) for early decoupled thermal relics, and \(m_s \gtrsim 10.2 \: \rm{keV}\) (95\% C.L.) for non-resonantly produced right-handed neutrinos. Combining the 1D Ly\(\alpha\) forest power spectrum measured by BOSS and XQ-100, we improve the two bounds to \(m_X \gtrsim 4.17 \: \rm{keV}\) and \(m_s \gtrsim 25.0 \: \rm{keV}\) (95\% C.L.). The \(3~\sigma\) bound shows a more significant improvement, increasing from \(m_X \gtrsim 2.74 \: \rm{keV}\) for BOSS alone to \(m_X \gtrsim 3.10 \: \rm{keV}\) for the combined BOSS+XQ-100 data set. Finally, we include in our analysis the first two redshift bins (\(z=4.2\) and \(z=4.6\)) of the power spectrum measured with the high-resolution HIRES/MIKE spectrographs. The addition of HIRES/MIKE power spectrum allows us to further improve the two limits to \(m_X \gtrsim 4.65 \: \rm{keV}\) and \(m_s \gtrsim 28.8 \: \rm{keV}\) (95\% C.L.).
We perform a multi-tracer analysis using the complete Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 luminous red galaxy (LRG) and the DR16 ...emission line galaxy (ELG) samples in the configuration space, and successfully detect a cross correlation between the two samples, and find the growth rate to be \(f\sigma_8=0.342 \pm 0.085\) (\(\sim25\) per cent accuracy) from the cross sample alone. We perform a joint measurement of the baryonic acoustic oscillation (BAO) and redshift space distortion (RSD) parameters at a single effective redshift of \(z_{\rm eff}= 0.77\), using the auto- and cross-correlation functions of the LRG and ELG samples, and find that the comoving angular diameter distance \(D_M(z_{\rm eff})/r_d = 18.85\pm 0.38\), the Hubble distance \(D_H(z_{\rm eff})/r_d = 19.64 \pm 0.57\), and \(f\sigma_8(z_{\rm eff}) = 0.432 \pm 0.038\), which is consistent with a \(\Lambda\)CDM model at \(68\%\) CL. Compared to the single-tracer analysis on the LRG sample, the Figure of Merit (FoM) of \(\alpha_{\perp}, \alpha_{||}\) and \(f\sigma_8\) is improved by a factor of \(1.11\) in our multi-tracer analysis, and in particular, the statistical uncertainty of \(f\sigma_8\) is reduced by \(11.6 \%\).
The DESI Legacy Imaging Surveys are a combination of three public projects (the Dark Energy Camera Legacy Survey, the Beijing-Arizona Sky Survey, and the Mayall z-band Legacy Survey) that will ...jointly image approximately 14,000 deg^2 of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The combined survey footprint is split into two contiguous areas by the Galactic plane. The optical imaging is conducted using a unique strategy of dynamically adjusting the exposure times and pointing selection during observing that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering a catalog, constructed by using a probabilistic inference-based approach to estimate source shapes and brightnesses. The catalog includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12 and 22 micorons) observed by the Wide-field Infrared Survey Explorer (WISE) satellite during its full operational lifetime. The project plans two public data releases each year. All the software used to generate the catalogs is also released with the data. This paper provides an overview of the Legacy Surveys project.
JCAP07(2020)010 The Lyman-$\alpha$ (hereafter Ly-$\alpha$) forest is a probe of large-scale
matter density fluctuations at high redshift, $z > 2.1$. It consists of HI
absorption spectra along ...individual lines-of-sight. If the line-of-sight
density is large enough, 3D maps of HI absorption can be inferred by
tomographic reconstruction. In this article, we investigate the Ly-$\alpha$
forest available in the Stripe 82 field ($220\,\mathrm{deg^{2}}$), based on the
quasar spectra from SDSS Data Release DR16. The density of observed quasar
spectra is $37\,\mathrm{deg^{-2}}$ with a mean pixel signal-to-noise ratio of
two per angstrom. This study provides an intermediate case between the average
SDSS density and that of the much denser but smaller CLAMATO survey. We derive
a 3D map of large-scale matter fluctuations from these data, using a Wiener
filter technique. The total volume of the map is $0.94\,\mathrm{h^{-3}
Gpc^{3}}$. Its resolution is $13\,\mathrm{h^{-1} Mpc}$, which is related to the
mean transverse distance between nearest lines-of-sight. From this map, we
provide a catalog of voids and protocluster candidates in the cosmic web. The
map-making and void catalog are compared to simulated eBOSS Stripe 82
observations. A stack over quasar positions provides a visualization of the
Ly-$\alpha$ quasar cross-correlation. This tomographic reconstruction
constitutes the largest-volume high-redshift 3D map of matter fluctuations.
This paper documents the sixteenth data release (DR16) from the Sloan Digital Sky Surveys; the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the ...southern hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey (TDSS) and new data from the SPectroscopic IDentification of ERosita Survey (SPIDERS) programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).
A&A 608, A130 (2017) We present a measurement of baryon acoustic oscillations (BAO) in the
cross-correlation of quasars with the Ly$\alpha$-forest flux-transmission at a
mean redshift $z=2.40$. The ...measurement uses the complete SDSS-III data sample:
168,889 forests and 234,367 quasars from the SDSS Data Release DR12. In
addition to the statistical improvement on our previous study using DR11, we
have implemented numerous improvements at the analysis level allowing a more
accurate measurement of this cross-correlation. We also developed the first
simulations of the cross-correlation allowing us to test different aspects of
our data analysis and to search for potential systematic errors in the
determination of the BAO peak position. We measure the two ratios
$D_{H}(z=2.40)/r_{d} = 9.01 \pm 0.36$ and $D_{M}(z=2.40)/r_{d} = 35.7 \pm 1.7$,
where the errors include marginalization over the non-linear velocity of
quasars and the metal - quasar cross-correlation contribution, among other
effects. These results are within $1.8\sigma$ of the prediction of the
flat-$\Lambda$CDM model describing the observed CMB anisotropies. We combine
this study with the Ly$\alpha$-forest auto-correlation function
2017A&A...603A..12B, yielding $D_{H}(z=2.40)/r_{d} = 8.94 \pm 0.22$ and
$D_{M}(z=2.40)/r_{d} = 36.6 \pm 1.2$, within $2.3\sigma$ of the same
flat-$\Lambda$CDM model.
Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (July ...2014-July 2017). This is the third data release for SDSS-IV, and the fifteenth from SDSS (Data Release Fifteen; DR15). New data come from MaNGA - we release 4824 datacubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g. stellar and gas kinematics, emission line, and other maps) from the MaNGA Data Analysis Pipeline (DAP), and a new data visualisation and access tool we call "Marvin". The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials and examples of data use. While SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020-2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.
A&A 603, A12 (2017) We use flux-transmission correlations in \Lya forests to measure the imprint
of baryon acoustic oscillations (BAO). The study uses spectra of 157,783
quasars in the redshift range ...$2.1\le z \le 3.5$ from the Sloan Digital Sky
Survey (SDSS) Data Release 12 (DR12). Besides the statistical improvements on
our previous studies using SDSS DR9 and DR11, we have implemented numerous
improvements in the analysis procedure, allowing us to construct a physical
model of the correlation function and to investigate potential systematic
errors in the determination of the BAO peak position. The Hubble distance,
$\DHub=c/H(z)$, relative to the sound horizon is $\DHub(z=2.33)/r_d=9.07 \pm
0.31$. The best-determined combination of comoving angular-diameter distance,
$\DM$, and the Hubble distance is found to be
$\DHub^{0.7}\DM^{0.3}/r_d=13.94\pm0.35$. This value is $1.028\pm0.026$ times
the prediction of the flat-\lcdm model consistent with the cosmic microwave
background (CMB) anisotropy spectrum. The errors include marginalization over
the effects of unidentified high-density absorption systems and fluctuations in
ultraviolet ionizing radiation. Independently of the CMB measurements, the
combination of our results and other BAO observations determine the open-\lcdm
density parameters to be $\om=0.296 \pm 0.029$, $\ol=0.699 \pm 0.100$ and
$\Omega_k = -0.002 \pm 0.119$.
The Lyman-\(\alpha\) (hereafter Ly-\(\alpha\)) forest is a probe of large-scale matter density fluctuations at high redshift, \(z > 2.1\). It consists of HI absorption spectra along individual ...lines-of-sight. If the line-of-sight density is large enough, 3D maps of HI absorption can be inferred by tomographic reconstruction. In this article, we investigate the Ly-\(\alpha\) forest available in the Stripe 82 field (\(220\,\mathrm{deg^{2}}\)), based on the quasar spectra from SDSS Data Release DR16. The density of observed quasar spectra is \(37\,\mathrm{deg^{-2}}\) with a mean pixel signal-to-noise ratio of two per angstrom. This study provides an intermediate case between the average SDSS density and that of the much denser but smaller CLAMATO survey. We derive a 3D map of large-scale matter fluctuations from these data, using a Wiener filter technique. The total volume of the map is \(0.94\,\mathrm{h^{-3} Gpc^{3}}\). Its resolution is \(13\,\mathrm{h^{-1} Mpc}\), which is related to the mean transverse distance between nearest lines-of-sight. From this map, we provide a catalog of voids and protocluster candidates in the cosmic web. The map-making and void catalog are compared to simulated eBOSS Stripe 82 observations. A stack over quasar positions provides a visualization of the Ly-\(\alpha\) quasar cross-correlation. This tomographic reconstruction constitutes the largest-volume high-redshift 3D map of matter fluctuations.
