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 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 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 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 Constraints on Growth Index from LSS

2014 ◽  
Vol 10 (S306) ◽  
pp. 255-257
Author(s):  
Athina Pouri ◽  
Spyros Basilakos ◽  
Manolis Plionis
Keyword(s):  
Growth Rate ◽  
Growth Index ◽  
Rate Data ◽  
Luminous Red Galaxies ◽  
A Value ◽  
Likelihood Analysis ◽  
Joint Likelihood ◽  
Λcdm Model ◽  
Red Galaxies ◽  
Good Agreement

AbstractWe utilize the clustering properties of the Luminous Red Galaxies (LRGs) and the growth rate data in order to constrain the growth index (γ) of the linear matter fluctuations based on a standard χ2joint likelihood analysis between theoretical expectations and data. We find a value of γ=0.56± 0.05, perfectly consistent with the expectations of the ΛCDM model, and Ωm0=0.29± 0.02, in very good agreement with the latest Planck results. Our analysis provides significantly more stringent growth index constraints with respect to previous studies as indicated by the fact that the corresponding uncertainty is only ∼ 0.09 γ.

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.

scholarly journals J-PAS: forecasts on interacting dark energy from baryon acoustic oscillations and redshift-space distortions

2019 ◽  
Vol 488 (1) ◽  
pp. 78-88 ◽  
Author(s):  
A A Costa ◽  
R J F Marcondes ◽  
R G Landim ◽  
E Abdalla ◽  
L R Abramo ◽  
...  
Keyword(s):  
Dark Energy ◽  
Acoustic Oscillations ◽  
Interacting Dark Energy ◽  
Photometric Redshift ◽  
Luminous Red Galaxies ◽  
Interaction Term ◽  
Emission Line Galaxies ◽  
Red Galaxies ◽  
Stay Behind ◽  
Matter Energy

ABSTRACT We estimate the constraining power of Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) for parameters of an interacting dark energy (DE) cosmology. The survey is expected to map several millions of luminous red galaxies, emission line galaxies, and quasars in an area of thousands of square degrees in the northern sky with precise photometric redshift measurements. Forecasts for the DESI and Euclid surveys are also evaluated and compared to J-PAS. Using the Fisher matrix approach, we find that J-PAS can place constraints on the interaction parameter comparable to those from DESI, with an absolute uncertainty of about 0.02, when the interaction term is proportional to the dark matter energy density, and almost as good, of about 0.01, when the interaction is proportional to the DE density. For the equation of state of DE, the constraints from J-PAS are slightly better in the two cases (uncertainties 0.04–0.05 against 0.05–0.07 around the fiducial value −1). Both surveys stay behind Euclid but follow it closely, imposing comparable constraints in all specific cases considered.

scholarly journals Age-dating Stellar Populations of Luminous Red Galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 265-267
Author(s):  
Ando Ratsimbazafy ◽  
Catherine Cress ◽  
Steve Crawford ◽  
Claudia Maraston ◽  
Robert Nichol ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Age Dating ◽  
Expansion Rate ◽  
Large Telescope ◽  
Luminous Red Galaxies ◽  
Sky Survey ◽  
Red Galaxies ◽  
Star Formation Histories ◽  
The Impact ◽  
The Universe

AbstractWe investigate the possibility of using Luminous Red Galaxies (LRGs) as “Cosmic chronometers” to measure the expansion rate of the universe to 3% over a redshift range 0.1 < z < 1.0. In this method, H(z) is directly measured by using the ages of passively evolving galaxies to determine dz/dt. We first present results from our study of LRGs in simulations Crawford et al. where we explore the impact of extended star formation histories on the measurements of the Hubble parameter. We then extract a carefully selected sample of LRGs taken from Sloan Digital Sky Survey (SDSS) Data Released Seven (DR7), stack spectra in redshift bins to increase the signal-to-noise, and use the Lick index modelling presented in Thomas et al. to age-date the sample. We discuss the implications for expansion rate measurements and outline a proposal to observe LRGs with the Southern African Large Telescope (SALT).

scholarly journals The impact of modified gravity on the Sunyaev-Zel’dovich effect

2020 ◽  
Author(s):  
Myles A Mitchell ◽  
Christian Arnold ◽  
César Hernández-Aguayo ◽  
Baojiu Li
Keyword(s):  
Galaxy Formation ◽  
Modified Gravity ◽  
Power Spectra ◽  
Substantial Effect ◽  
Formation Model ◽  
Modified Gravity Theories ◽  
Sunyaev Zel'dovich Effect ◽  
Normal Branch ◽  
Using Data ◽  
The Impact

Abstract We study the effects of two popular modified gravity theories, which incorporate very different screening mechanisms, on the angular power spectra of the thermal (tSZ) and kinematic (kSZ) components of the Sunyaev-Zel’dovich effect. Using the first cosmological simulations that simultaneously incorporate both screened modified gravity and a complete galaxy formation model, we find that the tSZ and kSZ power spectra are significantly enhanced by the strengthened gravitational forces in Hu-Sawicki f(R) gravity and the normal-branch Dvali-Gabadadze-Porrati model. Employing a combination of non-radiative and full-physics simulations, we find that the extra baryonic physics present in the latter acts to suppress the tSZ power on angular scales l ≳ 3000 and the kSZ power on all tested scales, and this is found to have a substantial effect on the model differences. Our results indicate that the tSZ and kSZ power can be used as powerful probes of gravity on large scales, using data from current and upcoming surveys, provided sufficient work is conducted to understand the sensitivity of the constraints to baryonic processes that are currently not fully understood.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Sign in / Sign up

Export Citation Format

Share Document