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Lim, Seunghwan

Publications and source records attributed to Lim, Seunghwan.

The extended Zel'dovich mass functions of clusters and isolated clusters in the presence of primordial non-gaussianity

We present new formulae for the mass functions of the clusters and the isolated clusters with non-Gaussian initial conditions. For this study, we adopt the extended Zel'dovich (EZL) model as a basic framework, focusing on the case of primordial non-Gaussianity of the local type whose degree is quantified by a single parameter, f {sub nl}. By making a quantitative comparison with the N-body results, we first demonstrate that the EZL formula with the constant values of three fitting parameters still works remarkably well for the local f {sub nl} case. We also modify the EZL formula to find an analytic expression for the mass function of isolated clusters, which turns out to have only one fitting parameter other than the overall normalization factor and showed that the modified EZL formula with a constant value of the fitting parameter matches excellently the N-body results with various values of f {sub nl} at various redshifts. Given the simplicity of the generalized EZL formulae and their good agreements with the numerical results, we finally conclude that the EZL mass functions of the massive clusters and isolated clusters should be useful as an analytic guideline to constrain the scale dependence of the primordial non-Gaussianity of the local type.

79 ASTRONOMY AND ASTROPHYSICS↗

An analytic formula for the supercluster mass function

We present an analytic formula for the supercluster mass function, which is constructed by modifying the extended Zel'dovich model for the halo mass function. The formula has two characteristic parameters whose best-fit values are determined by fitting to the numerical results from N-body simulations for the standard ΛCDM cosmology. The parameters are found to be independent of redshifts and robust against variation of the key cosmological parameters. Under the assumption that the same formula for the supercluster mass function is valid for non-standard cosmological models, we show that the relative abundance of the rich superclusters should be a powerful indicator of any deviation of the real universe from the prediction of the standard ΛCDM model.

79 ASTRONOMY AND ASTROPHYSICS↗

An extended Zel'dovich model for the halo mass function

A new way to construct a fitting formula for the halo mass function is presented. Our formula is expressed as a solution to the modified Jedamzik matrix equation that automatically satisfies the normalization constraint. The characteristic parameters expressed in terms of the linear shear eigenvalues are empirically determined by fitting the analytic formula to the numerical results from the high-resolution N-body simulation and found to be independent of scale, redshift and background cosmology. Our fitting formula with the best-fit parameters is shown to work excellently in the wide mass-range at various redshifts: The ratio of the analytic formula to the N-body results departs from unity by up to 10% and 5% over 10{sup 11} ≤ M/(h{sup −1}M{sub s}un) ≤ 5 × 10{sup 15} at z = 0,0.5 and 1 for the FoF-halo and SO-halo cases, respectively.

79 ASTRONOMY AND ASTROPHYSICS↗