The cluster-cluster correlation in hybrid models

view Abstract Citations (36) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galaxy mergers and active nuclei. I - The luminosity function. II - Cosmological evolution Roos, N. Abstract Theoretical models of active-galactic-nucleus (AGN) formation in galaxies with massive central black holes by the repopulation of stellar loss-cone orbits during galaxy mergers are investigated. A local AGN bolometric luminosity function is calculated for galaxies with Galaxy-like nuclear density distributions using a merging rate based on the two-point correlation function of galaxies and shown to be qualitatively similar to the observed luminosity functions in the visible, X-ray, and radio bands, with a power-law index of -1.4 at high luminosity and a break at radio luminosity about 10 to the 44th erg/s (corresponding to an interacting-galaxy mass ratio greater than 20). The cosmological evolution of the galaxy merging rate is considered, assuming galaxy formation at z = about 3 and galactic-stellar-luminosity-dependent evolution, and found to be faster at the bright end of the galaxy luminosity function. The merger rate outside rich clusters in an expanding universe is found to vary as the inverse of cosmic time. Publication: The Astrophysical Journal Pub Date: July 1985 DOI: 10.1086/163314 Bibcode: 1985ApJ...294..479R Keywords: Black Holes (Astronomy); Cosmology; Extragalactic Radio Sources; Galactic Clusters; Galactic Evolution; Galactic Nuclei; Interacting Galaxies; Luminosity; Active Galactic Nuclei; Astronomical Models; Bivariate Analysis; Mass Ratios; Quasars; Radio Galaxies; Red Shift; Seyfert Galaxies; Stellar Orbits; Astrophysics full text sources ADS |

We perform theoretical and numerical studies of the full relativistic two-point galaxy correlation function, considering the linear-order scalar and tensor perturbation contributions and the wide-angle effects. Using the gauge-invariant relativistic description of galaxy clustering and accounting for the contributions at the observer position, we demonstrate that the complete theoretical expression is devoid of any long-mode contributions from scalar or tensor perturbations and it lacks the infrared divergences in agreement with the equivalence principle. By showing that the gravitational potential contribution to the correlation function converges in the infrared, our study justifies an IR cut-off (kIR ⩽ H0) in computing the gravitational potential contribution. Using the full gauge-invariant expression, we numerically compute the galaxy two-point correlation function and study the individual contributions in the conformal Newtonian gauge. We find that the terms at the observer position such as the coordinate lapses and the observer velocity (missing in the standard formalism) dominate over the other relativistic contributions in the conformal Newtonian gauge such as the source velocity, the gravitational potential, the integrated Sachs-Wolf effect, the Shapiro time-delay and the lensing convergence. Compared to the standard Newtonian theoretical predictions that consider only the density fluctuation and redshift-space distortions, the relativistic effects in galaxy clustering result in a few percent-level systematic errors beyond the scale of the baryonic acoustic oscillation (∼ 2% at 150 Mpc/h and redshift one). Our theoretical and numerical study provides a comprehensive understanding of the relativistic effects in the galaxy two-point correlation function, as it proves the validity of the theoretical prediction and accounts for effects that are often neglected in its numerical evaluation.

We present a new method that simultaneously solves for cosmology and galaxy bias on non-linear scales. The method uses the halo model to analytically describe the (non-linear) matter distribution, and the conditional luminosity function (CLF) to specify the halo occupation statistics. For a given choice of cosmological parameters, this model can be used to predict the galaxy luminosity function, as well as the two-point correlation functions of galaxies, and the galaxy–galaxy lensing signal, both as a function of scale and luminosity. These observables have been reliably measured from the Sloan Digital Sky Survey. In this paper, the first in a series, we present the detailed, analytical model, which we test against mock galaxy redshift surveys constructed from high-resolution numerical N-body simulations. We demonstrate that our model, which includes scale dependence of the halo bias and a proper treatment of halo exclusion, reproduces the three-dimensional galaxy–galaxy correlation and the galaxy–matter cross-correlation (which can be projected to predict the observables) with an accuracy better than 10 (in most cases 5) per cent. Ignoring either of these effects, as is often done, results in systematic errors that easily exceed 40 per cent on scales of ∼ 1 h− 1 Mpc, where the data are typically most accurate. Finally, since the projected correlation functions of galaxies are never obtained by integrating the redshift-space correlation function along the line of sight out to infinity, simply because the data only cover a finite volume, they are still affected by residual redshift-space distortions (RRSDs). Ignoring these, as done in numerous studies in the past, results in systematic errors that easily exceed 20 per cent on large scales (rp ≳ 10 h− 1 Mpc). We show that it is fairly straightforward to correct for these RRSDs, to an accuracy better than ∼ 2 per cent, using a mildly modified version of the linear Kaiser formalism.

Despite many independent estimates, there has been little consensus reached as to the form of the two-point angular correlation function of galaxies. The two-point angular correlation function for the recently completed Edinburgh-Durham Southern Galaxy Catalogue. This galaxy survey consists of digitized COSMOS scans for 60 UK Schmid fields centred at the South Galactic Pole. The w(θ) results from the catalogue are presented at four depths: b j = 17.5, 18.5, 19.5 and 20.3

It is usually assumed that in the linear regime the two-point correlation function of galaxies contains only a monopole, quadrupole and hexadecapole. Looking at cross-correlations between different populations of galaxies, this turns out not to be the case. In particular, the cross-correlations between a bright and a faint population of galaxies contain also a dipole. In this paper we present the first attempt to measure this dipole. We discuss the four types of effects that contribute to the dipole: relativistic distortions, evolution effect, wide-angle effect and large-angle effect. We show that the first three contributions are intrinsic anti-symmetric contributions that do not depend on the choice of angle used to measure the dipole. On the other hand the large-angle effect appears only if the angle chosen to extract the dipole breaks the symmetry of the problem. We show that the relativistic distortions, the evolution effect and the wide-angle effect are too small to be detected in the LOWz and CMASS sample of the BOSS survey. On the other hand with a specific combination of angles we are able to measure the large-angle effect with high significance. We emphasise that this large-angle dipole does not contain new physical information, since it is just a geometrical combination of the monopole and the quadrupole. However this measurement, which is in excellent agreement with theoretical predictions, validates our method for extracting the dipole from the two-point correlation function and it opens the way to the detection of relativistic effects in future surveys like e.g. DESI.

We calculate the two-point correlation function for a sample of ringed galaxies. Results are similar to that of general field galaxies. We also find evidence that these galaxies form very large scale structures.

view Abstract Citations (18) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Angular Correlation Function of Faint Galaxies Yoshii, Yuzuru ; Peterson, Bruce A. ; Takahara, Fumio Abstract Predictions of the angular two-point correlation function of faint galaxies, that are consistent with N-body simulations of clustering evolution and with the redshift distribution of faint galaxies obtained when selection effects are taken into account, are presented for various model universes. We find that the clustering amplitude is not a monotonic function of the cosmological parameters, exhibiting a complicated dependence on the model universe. It is found that recent measurements of the small-scale angular correlation of faint galaxies are consistent with both a flat CDM-dominated universe and a flat vacuum-dominated universe. Increasing the bias and/or lowering {OMEGA}_0_ with a vanishing cosmological constant gives high clustering amplitudes in excess of the observed level, and these models are incompatible with the observations. The conclusion drawn by Efstathiou et al. (1991) that the gravitational clustering in a flat CDM universe conflicts with their data is not justified. Publication: The Astrophysical Journal Pub Date: September 1993 DOI: 10.1086/173089 Bibcode: 1993ApJ...414..431Y Keywords: Angular Distribution; Cosmology; Faint Objects; Galactic Evolution; Galaxies; Astronomical Photometry; Dark Matter; Gravitational Effects; Many Body Problem; Astrophysics; GALAXIES: PHOTOMETRY; COSMOLOGY: OBSERVATIONS; COSMOLOGY: THEORY; GALAXIES: CLUSTERING; GALAXIES: EVOLUTION full text sources ADS |

The most common and reliable method of studying the large scale structure of the universe is through the space distribution of galaxies. and one of the most powerful tools in studying the large scale structure is the two-point correlation function of galaxies [1–5]. The study of the distribution of galaxies has confirmed the existence of superclusters and revealed the string-void structure (e.g. from the cfA survey with a limiting magnitude in 14.m5) or the bubble-void structure (e.g. from cfA survey down to 15m5 [6]). All the results and conclusions are very important for the understanding of the cosmological evolutional scenario and the theory of galaxy formation and evolution.[1.8]

We present an improved framework for estimating the growth rate of large-scale structure, using measurements of the galaxy–velocity cross-correlation in configuration space. We consider standard estimators of the velocity autocorrelation function, ψ1 and ψ2, the two-point galaxy correlation function, ξgg, and introduce a new estimator of the galaxy–velocity cross-correlation function, ψ3. By including pair counts measured from random catalogues of velocities and positions sampled from distributions characteristic of the true data, we find that the variance in the galaxy–velocity cross-correlation function is significantly reduced. Applying a covariance analysis and χ2 minimization procedure to these statistics, we determine estimates and errors for the normalized growth rate fσ8 and the parameter β = f/b, where b is the galaxy bias factor. We test this framework on mock hemisphere data sets for redshift z < 0.1 with realistic velocity noise constructed from the l-picola simulation code, and find that we are able to recover the fiducial value of fσ8 from the joint combination of ψ1 + ψ2 + ψ3 + ξgg, with 15 per cent accuracy from individual mocks. We also recover the fiducial fσ8 to within 1σ regardless of the combination of correlation statistics used. When we consider all four statistics together we find that the statistical uncertainty in our measurement of the growth rate is reduced by $59{{\ \rm per\ cent}}$ compared to the same analysis only considering ψ2, by $53{{\ \rm per\ cent}}$ compared to the same analysis only considering ψ1, and by $52{{\ \rm per\ cent}}$ compared to the same analysis jointly considering ψ1 and ψ2.

The observed two-point correlation functions of galaxies in redshift space become anisotropic because of the geometry of the universe, as well as because of the presence of the peculiar velocity field. On the basis of linear perturbation theory, we expand the induced anisotropies of the correlation functions with respect to the redshift z and obtain analytic formulae to infer the deceleration parameter q0, the density parameter Ω0, and the derivative of the bias parameter d ln b/dz at z = 0 in terms of the observable statistical quantities. The present method does not require any assumption of the shape and amplitude of the underlying fluctuation spectrum and thus can be applied to future redshift surveys of galaxies, including the Sloan Digital Sky Survey. We also evaluate quantitatively the systematic error in estimating the value of β0 ≡ Ω00.6/b from a galaxy redshift survey on the basis of a conventional estimator for β0, which neglects both the geometrical distortion effect and the time evolution of the parameter β(z). If the magnitude limit of the survey is as faint as 18.5 (in B band) as in the case of the Sloan Digital Sky Survey, the systematic error ranges between -20% and 10% depending on the cosmological parameters. Although such systematic errors are smaller than the statistical errors in the current surveys, they will definitely dominate the expected statistical error for future surveys.

view Abstract Citations (22) References (57) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Scaling Analysis as a Tool to Compare N-Body Simulations with Observations: Application to a Low-Bias Cold Dark Matter Model Yepes, G. ; Dominguez-Tenreiro, R. ; Couchman, H. M. P. Abstract We show that the scaling or multifractal analysis is specially suited to quantify the clustering properties of galaxy distributions. The information provided by this method of volume-limited samples is not masked by the boundary corrections made. Consequently, the formalism could be a useful tool to compare the outputs of N-body simulations and galaxy catalogs. The multifractal statistical analysis has been applied to the output of a highly evolved, low bias (b_l_~ 0.8), {OMEGA} = 1 cold dark matter simulation with 128^3^ particles in a 100 h^-1^ Mpc cubic volume. The identification of galaxy tracers in this simulation is carried out by means of an algorithm that mimics the formation and merging of galaxies. The same statistical analysis has been performed in several samples of the 14.5 CfA galaxy catalog. From the comparison of both analyses we conclude that there exists a very good agreement in the overall clustering properties of the observational samples and the simulation, as described by the statistical method. Publication: The Astrophysical Journal Pub Date: December 1992 DOI: 10.1086/172036 Bibcode: 1992ApJ...401...40Y Keywords: Cosmology; Dark Matter; Galactic Clusters; Many Body Problem; Scaling Laws; Computerized Simulation; Fractals; Interacting Galaxies; Red Shift; Spatial Distribution; Astrophysics; COSMOLOGY: DARK MATTER; GALAXIES: CLUSTERING; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; METHODS: NUMERICAL full text sources ADS |

We show how a characteristic length scale imprinted in the galaxy two-point correlation function, dubbed the "linear point," can serve as a comoving cosmological standard ruler. In contrast to the baryon acoustic oscillation peak location, this scale is constant in redshift and is unaffected by nonlinear effects to within 0.5 percent precision. We measure the location of the linear point in the galaxy correlation function of the LOWZ and CMASS samples from the Twelfth Data Release (DR12) of the Baryon Oscillation Spectroscopic Survey (BOSS) Collaboration. We combine our linear-point measurement with cosmic-microwave-background constraints from the Planck satellite to estimate the isotropic-volume distance D_{V}(z), without relying on a model-template or "reconstruction" method. We find D_{V}(0.32)=1264±28 Mpc and D_{V}(0.57)=2056±22 Mpc, respectively, consistent with the quoted values from the BOSS Collaboration. This remarkable result suggests that all the distance information contained in the baryon acoustic oscillations can be conveniently compressed into the single length associated with the linear point.

view Abstract Citations (16) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mixed Dark Matter from Neutrino Lasing Starkman, G. D. ; Kaiser, N. ; Malaney, R. A. Abstract We investigate the production of dark matter with non-standard momentum distributions arising from the decay of a relativistic massive neutrino into a lighter fermion and boson H$\rightarrow$F$+$B. We develop the Boltzmann equations for this process, paying particular attention to spin polarisation effects. Such decays can, under certain circumstances, lead to a process of runaway stimulated decays or `neutrino-lasing' resulting, for suitable boson mass, in the production of mixed-dark-matter. We discuss a number of variations on the model; we show how the yield of cold particles can be increased by a simple modification to our original proposal. We discuss the singlet-majoron model as a possible framework for these decays. Publication: The Astrophysical Journal Pub Date: October 1994 DOI: 10.1086/174700 arXiv: arXiv:astro-ph/9312020 Bibcode: 1994ApJ...434...12S Keywords: Boltzmann Transport Equation; Dark Matter; Lasing; Momentum; Neutrinos; Polarization (Spin Alignment); Astronomical Models; Bosons; Cosmic Background Explorer Satellite; Fermions; Nuclear Fusion; Universe; Astronomy; COSMOLOGY: DARK MATTER; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; ELEMENTARY PARTICLES; Astrophysics; High Energy Physics - Phenomenology E-Print: 23 pages, latex, CITA/93/49, available by anon ftp from ftp.cita.utoronto.ca in /cita/nick/neutrinolasing2.ps full text sources arXiv | ADS |

Theoretical forms of two- and three-point galaxy correlation functions

view Abstract Citations (30) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cluster-cluster clustering Barnes, J. ; Dekel, A. ; Efstathiou, G. ; Frenk, C. S. Abstract The cluster correlation function xic(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xic and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xic increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xic is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xic found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. Publication: The Astrophysical Journal Pub Date: August 1985 DOI: 10.1086/163381 Bibcode: 1985ApJ...295..368B Keywords: Astronomical Models; Correlation; Cosmology; Galactic Clusters; Algorithms; Many Body Problem; Mass Distribution; White Noise; Astrophysics full text sources ADS |