scholarly journals Clustering of dark halos on the lightcone

2003 ◽  
Vol 208 ◽  
pp. 467-468
Author(s):  
Naoki Yoshida ◽  
Takashi Hamana ◽  
Yasushi Suto ◽  
August Evrard
Keyword(s):  
Dark Matter ◽  
Phenomenological Model ◽  
Correlation Functions ◽  
Light Cone ◽  
Theoretical Models ◽  
Dark Matter Halos ◽  
Model Predictions ◽  
Astrophysical Objects ◽  
Point Correlation ◽  
Good Agreement

We present a phenomenological model to predict the clustering of dark matter halos on the light-cone. The model is constructed by combining several existing theoretical models. We test our model against the Hubble Volume N-body simulation and examine its validity. A good agreement is found in two-point correlation functions of dark matter halos between our model predictions and measurements from the simulation. The model is quite general and thus can be applied to a wider range of astrophysical objects, such as galaxies and quasars.

scholarly journals Towards a self-consistent analysis of the anisotropic galaxy two- and three-point correlation functions on large scales: application to mock galaxy catalogues

2020 ◽  
Author(s):  
Naonori S Sugiyama ◽  
Shun Saito ◽  
Florian Beutler ◽  
Hee-Jong Seo
Keyword(s):  
Correlation Functions ◽  
Hubble Parameter ◽  
Theoretical Models ◽  
Practical Method ◽  
Acoustic Oscillation ◽  
Nonlinear Damping ◽  
Joint Analysis ◽  
Angular Diameter Distance ◽  
Point Correlation ◽  
Parameter Constraints

Abstract We establish a practical method for the joint analysis of anisotropic galaxy two- and three-point correlation functions (2PCF and 3PCF) on the basis of the decomposition formalism of the 3PCF using tri-polar spherical harmonics. We perform such an analysis with MultiDark Patchy mock catalogues to demonstrate and understand the benefit of the anisotropic 3PCF. We focus on scales above 80 h−1 Mpc, and use information from the shape and the baryon acoustic oscillation (BAO) signals of the 2PCF and 3PCF. We also apply density field reconstruction to increase the signal-noise ratio of BAO in the 2PCF measurement, but not in the 3PCF measurement. In particular, we study in detail the constraints on the angular diameter distance and the Hubble parameter. We build a model of the bispectrum or 3PCF that includes the nonlinear damping of the BAO signal in redshift space. We carefully account for various uncertainties in our analysis including theoretical models of the 3PCF, window function corrections, biases in estimated parameters from the fiducial values, the number of mock realizations to estimate the covariance matrix, and bin size. The joint analysis of the 2PCF and 3PCF monopole and quadrupole components shows a $30\%$ and $20\%$ improvement in Hubble parameter constraints before and after reconstruction of the 2PCF measurements, respectively, compared to the 2PCF analysis alone. This study clearly shows that the anisotropic 3PCF increases cosmological information from galaxy surveys and encourages further development of the modeling of the 3PCF on smaller scales than we consider.

A PHENOMENOLOGICAL MODEL FOR HYDROGELS WITH RIGID SKIN FORMATION

2012 ◽  
Vol 04 (01) ◽  
pp. 1250007 ◽  
Author(s):  
JUNDIKA CANDRA KURNIA ◽  
ERIK BIRGERSSON ◽  
ARUN S. MUJUMDAR
Keyword(s):  
Phenomenological Model ◽  
Interstitial Fluid ◽  
Polymer Network ◽  
Rigid Core ◽  
Deformation Kinetics ◽  
Model Predictions ◽  
Experimental Deformation ◽  
Skin Formation ◽  
Stimuli Sensitive ◽  
Good Agreement

A phenomenological model for stimuli sensitive hydrogels immersed in water subject to changes in temperature is presented and analyzed. In short, the model takes into account conservation of mass and momentum for polymer network and interstitial fluid with an expression for permeability to capture the rigid skin formation during shrinking. The nature of this expression is secured from the observation of and validation with experimental deformation kinetics. Overall, good agreement is achieved between model predictions and their experimental counterparts; the rigid skin formation and rigid core presence are also captured reasonably well. The model can be extended to account for arbitrary-shaped hydrogels as well as for other types of stimuli-sensitive hydrogels that exhibit rigid-skin formation during shrinking.

scholarly journals Dependence on the environment of the abundance function of light-cone simulation dark matter haloes

2018 ◽  
Vol 616 ◽  
pp. A137 ◽  
Author(s):  
Maria Chira ◽  
Manolis Plionis ◽  
Pier-Stefano Corasaniti
Keyword(s):  
Dark Matter ◽  
Power Law ◽  
Phenomenological Model ◽  
Light Cone ◽  
Dark Matter Halo ◽  
Nearest Neighbour ◽  
Spherical Region ◽  
Theoretical Mass ◽  
Mass Functions ◽  
Characteristic Mass

Aims. We study the dependence of the halo abundance function (AF) on different environments in a whole-sky ΛCDM light-cone halo catalogue extending to z ~ 0.65, using a simple and well-defined halo isolation criterion. Methods. The isolation status of each individual dark matter halo is determined by the distance to its nearest neighbour, which defines the maximum spherical region devoid of halos above a threshold mass around it (although the true size of such region may be much larger since it is not necessarily spherical). A versatile double power-law Schechter function is used to fit the dark matter halo AF, and its derived parameters are studied as a function of halo isolation status. Results. (a) Our function fits the halo abundances for all halo isolation statuses extremely well, while the well-established theoretical mass functions, integrated over the volume of the light-cone, provide an adequate but poorer fit than our phenomenological model. (b) As expected, and in agreement with other studies based on snap-shot simulations, we find significant differences of the halo abundance function as a function of halo isolation, indicating different rates of halo formation. The slope of the power law and the characteristic mass of the Schechter-like fitting function decrease with isolation, a result consistent with the formation of less massive haloes in lower density regions. (c) We find an unexpected upturn of the characteristic mass of the most isolated haloes of our sample. This upturn originates and characterises only the higher redshift regime (z ≳ 0.45), which probably implies a significant and recent evolution of the isolation status of the most isolated and most massive haloes.

scholarly journals Testing tidal alignment models for anisotropic correlations of halo ellipticities with N-body simulations

2020 ◽  
Vol 494 (1) ◽  
pp. 694-702 ◽  
Author(s):  
Teppei Okumura ◽  
Atsushi Taruya ◽  
Takahiro Nishimichi
Keyword(s):  
Dark Matter ◽  
Large Volume ◽  
Correlation Functions ◽  
Clustering Analysis ◽  
Large Scale ◽  
Acoustic Oscillations ◽  
Model Predictions ◽  
Alignment Model ◽  
Linear Alignment ◽  
Scale Limit

ABSTRACT There is a growing interest of using the intrinsic alignment (IA) of galaxy images as a tool to extract cosmological information complimentary to galaxy clustering analysis. Recently, Okumura & Taruya derived useful formulas for the intrinsic ellipticity–ellipticity correlation, the gravitational shear–intrinsic ellipticity correlation, and the velocity–intrinsic ellipticity correlation functions based on the linear alignment (LA) model. In this paper, using large-volume N-body simulations, we measure these alignment statistics for dark-matter haloes in real and redshift space and compare them to the LA and non-linear alignment model predictions. We find that anisotropic features of baryon acoustic oscillations in the IA statistics can be accurately predicted by our models. The anisotropy due to redshift-space distortions (RSDs) is also well described in the large-scale limit. Our results indicate that one can extract the cosmological information encoded in the IA through the Alcock–Paczynski and RSD effects.

scholarly journals On the contribution of different coupling constants in the infrared regime of Yang–Mills theory: A Curci–Ferrari approach

2019 ◽  
Vol 34 (32) ◽  
pp. 1950214
Author(s):  
Matías Fernández ◽  
Marcela Peláez
Keyword(s):  
Perturbation Theory ◽  
Correlation Functions ◽  
Landau Gauge ◽  
Phenomenological Description ◽  
Coupling Constants ◽  
Lattice Data ◽  
Yang Mills ◽  
Point Correlation ◽  
Good Agreement

We investigate the influence of the different vertices of two-point correlation functions in the infrared regime of Yang–Mills theory using a phenomenological description. This regime is studied in Landau-gauge and using perturbation theory within a phenomenological massive model. We perform a one-loop calculation for two-point correlation functions taking into account the different roles of the various interactions in the infrared. Our results show a good agreement with the lattice data.

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