scholarly journals Traces of Anisotropic Quasi-Regular Structure in the SDSS Data

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 289
Author(s):  
Andrei I. Ryabinkov ◽  
Alexander D. Kaminker
Keyword(s):  
Preliminary Analysis ◽  
Large Scale ◽  
Power Spectra ◽  
Regular Structure ◽  
Characteristic Scale ◽  
Spherical Coordinate ◽  
Luminous Red Galaxies ◽  
Special Direction ◽  
Red Galaxies ◽  
Periodical Component

The aim of this study is to search for quasi-periodical structures at moderate cosmological redshifts z ≲ 0.5. We mainly use the SDSS DR7 data on the luminous red galaxies (LRGs)with redshifts 0.16 ≤ z ≤ 0.47. At first, we analyze features (peaks) in the power spectra of radial (shell-like) distributions using separate angular sectors in the sky and calculate the power spectra within each sector. As a result, we found some signs of a large-scale anisotropic quasi-periodic structure detectable through 6 sectors out of a total of 144 sectors. These sectors are distinguished by large amplitudes of dominant peaks in their radial power spectra at wavenumbers k within a narrow interval of 0.05 < k < 0.07 h Mpc−1. Then, passing from a spherical coordinate system to a Cartesian one, we found a special direction such that the total distribution of LRG projections on it contains a significant (≳5σ) quasi-periodical component. We assume that we are dealing with a signature of a quasi-regular structure with a characteristic scale 116 ± 10 h−1 Mpc. Our assumption is confirmed by a preliminary analysis of the SDSS DR12 data.

scholarly journals 21 cm Line Study of Large Scale Density Fluctuations in the Taurus Molecular Complex

1987 ◽  
Vol 115 ◽  
pp. 67-68
Author(s):  
W.L.H. Shuter ◽  
R. L. Dickman ◽  
C. Klatt
Keyword(s):  
Correlation Length ◽  
Molecular Complex ◽  
Preliminary Analysis ◽  
Large Scale ◽  
Power Spectra ◽  
Density Fluctuations ◽  
Central Point ◽  
Spectral Peak ◽  
Autocorrelation Functions ◽  
Power Spectral

21-cm spectra on a 41 × 31 grid, centered at 1950: RA 04h30m; DEC 27d00m, at points separated by a true angle of 0.25 degrees, were observed using the Arecibo telescope in October 1985. The identical grid had previously been observed in 13CO by Kleiner and Dickman (1984) with the FCRAO mm wave telescope. In this preliminary analysis we determined autocorrelation functions and power spectra for 21-cm self absorption “intensities”, for a cross passing through the central point. Both arms of the cross, aligned parallel to RA and DEC, show a power spectral peak at a frequency of 0.312 reciprocal degrees, corresponding to a period of 3.2 degrees on the sky. Assuming that the Taurus complex is at a distance of 140 pc, this corresponds to a correlation length of 7.8 pc, which is about a factor of two smaller than the value of 14 pc found by Kleiner and Dickman for 13CO.

scholarly journals Matter power spectrum: from Ly α forest to CMB scales

2019 ◽  
Vol 489 (2) ◽  
pp. 2247-2253 ◽  
Author(s):  
Solène Chabanier ◽  
Marius Millea ◽  
Nathalie Palanque-Delabrouille
Keyword(s):  
Power Spectrum ◽  
Power Spectra ◽  
Model Fit ◽  
Microwave Background ◽  
Luminous Red Galaxies ◽  
Matter Power Spectrum ◽  
Physical Scale ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Red Galaxies

ABSTRACT We present a new compilation of inferences of the linear 3D matter power spectrum at redshift $z\, {=}\, 0$ from a variety of probes spanning several orders of magnitude in physical scale and in cosmic history. We develop a new lower noise method for performing this inference from the latest Ly α forest 1D power spectrum data. We also include cosmic microwave background (CMB) temperature and polarization power spectra and lensing reconstruction data, the cosmic shear two-point correlation function, and the clustering of luminous red galaxies. We provide a Dockerized Jupyter notebook housing the fairly complex dependences for producing the plot of these data, with the hope that groups in the future can help add to it. Overall, we find qualitative agreement between the independent measurements considered here and the standard ΛCDM cosmological model fit to the Planck data.

scholarly journals Imaging systematics and clustering of DESI main targets

2020 ◽  
Vol 496 (2) ◽  
pp. 2262-2291 ◽  
Author(s):  
Ellie Kitanidis ◽  
Martin White ◽  
Yu Feng ◽  
David Schlegel ◽  
Julien Guy ◽  
...  
Keyword(s):  
Power Spectra ◽  
Luminous Red Galaxies ◽  
Cross Correlations ◽  
Emission Line Galaxies ◽  
Using Data ◽  
Red Galaxies ◽  
The Impact ◽  
Stellar Density ◽  
North Galactic ◽  
Good Agreement

ABSTRACT We evaluate the impact of imaging systematics on the clustering of luminous red galaxies (LRG), emission-line galaxies (ELG), and quasars (QSO) targeted for the upcoming Dark Energy Spectroscopic Instrument (DESI) survey. Using Data Release 7 of the DECam Legacy Survey, we study the effects of astrophysical foregrounds, stellar contamination, differences between north galactic cap and south galactic cap measurements, and variations in imaging depth, stellar density, galactic extinction, seeing, airmass, sky brightness, and exposure time before presenting survey masks and weights to mitigate these effects. With our sanitized samples in hand, we conduct a preliminary analysis of the clustering amplitude and evolution of the DESI main targets. From measurements of the angular correlation functions, we determine power law fits $r_0 = 7.78 \pm 0.26\, h^{-1}$Mpc, γ = 1.98 ± 0.02 for LRGs and $r_0 = 5.45 \pm 0.1\, h^{-1}$Mpc, γ = 1.54 ± 0.01 for ELGs. Additionally, from the angular power spectra, we measure the linear biases and model the scale-dependent biases in the weakly non-linear regime. Both sets of clustering measurements show good agreement with survey requirements for LRGs and ELGs, attesting that these samples will enable DESI to achieve precise cosmological constraints. We also present clustering as a function of magnitude, use cross-correlations with external spectroscopy to infer dN/dz and measure clustering as a function of luminosity, and probe higher order clustering statistics through counts-in-cells moments.

scholarly journals Cross-Correlation of Planck CMB Lensing with DESI-Like LRGs

2020 ◽  
Author(s):  
Ellie Kitanidis ◽  
Martin White
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Theory Model ◽  
Microwave Background ◽  
Redshift Distribution ◽  
Luminous Red Galaxies ◽  
Bias Model ◽  
Cross Correlations ◽  
Galaxy Bias ◽  
Red Galaxies

Abstract Cross-correlations between the lensing of the cosmic microwave background (CMB) and other tracers of large-scale structure provide a unique way to reconstruct the growth of dark matter, break degeneracies between cosmology and galaxy physics, and test theories of modified gravity. We detect a cross-correlation between DESI-like luminous red galaxies (LRGs) selected from DECaLS imaging and CMB lensing maps reconstructed with the Planck satellite at a significance of S/N = 27.2 over scales ℓmin = 30, ℓmax = 1000. To correct for magnification bias, we determine the slope of the LRG cumulative magnitude function at the faint limit as s = 0.999 ± 0.015, and find corresponding corrections on the order of a few percent for $C^{\kappa g}_{\ell }, C^{gg}_{\ell }$ across the scales of interest. We fit the large-scale galaxy bias at the effective redshift of the cross-correlation zeff ≈ 0.68 using two different bias evolution agnostic models: a HaloFit times linear bias model where the bias evolution is folded into the clustering-based estimation of the redshift kernel, and a Lagrangian perturbation theory model of the clustering evaluated at zeff. We also determine the error on the bias from uncertainty in the redshift distribution; within this error, the two methods show excellent agreement with each other and with DESI survey expectations.

scholarly journals The VIMOS Public Extragalactic Redshift Survey (VIPERS)

2018 ◽  
Vol 610 ◽  
pp. A59 ◽  
Author(s):  
F. G. Mohammad ◽  
B. R. Granett ◽  
L. Guzzo ◽  
J. Bel ◽  
E. Branchini ◽  
...  
Keyword(s):  
Correlation Function ◽  
Systematic Error ◽  
Large Scale ◽  
Power Spectra ◽  
Limited Sample ◽  
Non Linear ◽  
Blue Galaxies ◽  
Colour Distribution ◽  
Redshift Survey ◽  
Red Galaxies

We used the VIMOS Public Extragalactic Redshift Survey (VIPERS) final data release (PDR-2) to investigate the performance of colour-selected populations of galaxies as tracers of linear large-scale motions. We empirically selected volume-limited samples of blue and red galaxies as to minimise the systematic error on the estimate of the growth rate of structure fσ8 from the anisotropy of the two-point correlation function. To this end, rather than rigidly splitting the sample into two colour classes we defined the red or blue fractional contribution of each object through a weight based on the (U − V) colour distribution. Using mock surveys that are designed to reproduce the observed properties of VIPERS galaxies, we find the systematic error in recovering the fiducial value of fσ8 to be minimised when using a volume-limited sample of luminous blue galaxies. We modelled non-linear corrections via the Scoccimarro extension of the Kaiser model (with updated fitting formulae for the velocity power spectra), finding systematic errors on fσ8 of below 1–2%, using scales as small as 5 h−1 Mpc. We interpret this result as indicating that selection of luminous blue galaxies maximises the fraction that are central objects in their dark matter haloes; this in turn minimises the contribution to the measured ξ(rp,π) from the 1-halo term, which is dominated by non-linear motions. The gain is inferior if one uses the full magnitude-limited sample of blue objects, consistent with the presence of a significant fraction of blue, fainter satellites dominated by non-streaming, orbital velocities. We measured a value of f σ8 = 0.45 ± 0.11 over the single redshift range 0.6 ≤ z ≤ 1.0, corresponding to an effective redshift for the blue galaxies 〈z〉=0.85. Including in the likelihood the potential extra information contained in the blue-red galaxy cross-correlation function does not lead to an appreciable improvement in the error bars, while it increases the systematic error.

scholarly journals Developing a unified pipeline for large-scale structure data analysis with angular power spectra – III. Implementing the multi-tracer technique to constrain neutrino masses

2020 ◽  
Author(s):  
Konstantinos Tanidis ◽  
Stefano Camera
Keyword(s):  
Large Scale ◽  
Power Spectra ◽  
Density Fluctuations ◽  
Harmonic Space ◽  
Neutrino Masses ◽  
Matrix Formalism ◽  
Tracer Technique ◽  
Emission Line Galaxies ◽  
Red Galaxies ◽  
Parameter Constraints

Abstract In this paper, we apply the multi-tracer technique to harmonic-space (i.e. angular) power spectra with a likelihood-based approach. This goes beyond the usual Fisher matrix formalism hitherto implemented in forecasts with angular statistics, opening up a window for future developments and direct application to available data sets. We also release a fully-operational modified version of the publicly available code CosmoSIS, where we consistently include all the add-ons presented in the previous papers of this series. The result is a modular cosmological parameter estimation suite for angular power spectra of galaxy number counts, allowing for single and multiple tracers, and including density fluctuations, redshift-space distortions, and weak lensing magnification. We demonstrate the improvement on parameter constraints enabled by the use of multiple tracers on a multi-tracing analysis of luminous red galaxies and emission line galaxies. We obtain an enhancement of $44\%$ on the 2σ upper bound on the sum of neutrino masses.

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