Bias and Conditional Mass Function of Dark Halos Based on the Nonspherical Collapse Model
نویسندگان
چکیده
Nonspherical collapse is modelled, under the Zeldovich approximation, by sixdimensional random walks of the initial deformation tensor field. The collapse boundary adopted here is a slightly-modified version of that proposed by Chiueh and Lee (2001). Not only the mass function agrees with the fitting formula of Sheth and Tormen (1999), but the bias function and conditional mass function constructed by this model are also found to agree reasonably well with the simulation results of Jing (1998) and Somerville et al. (2000), respectively. In particular, by introducing a small mass gap, we find a fitting formula for the conditional mass function, which works well even at small time intervals between parent and progenitor halos during the merging history. Subject headings: galaxies:clusters:general cosmology:theory large-scale structure of universe Email: [email protected] Email: [email protected] Email: [email protected]
منابع مشابه
Bias and Conditional Mass Function of Nonspherical Dark Halos
Nonspherical collapse is modelled, under the Zeldovich approximation, by sixdimensional random walks of the initial deformation tensor field. The collapse boundary adopted here is a slightly-modified version of that proposed by Chiueh and Lee (2001). Not only the mass function agrees with the fitting formula of Sheth and Tormen (1999), but the bias function and conditional mass function constru...
متن کاملOn the Nonspherical Nature of Halo Formation
We present a new collapse condition to describe the formation of dark halos via nonspherical gravitational clustering. This new nonspherical collapse condition is obtained by the logical generalization of the spherical model to the nonspherical one. By solving a diffusion-like random matrix equation with the help of the Monte Carlo method, we show that this nonspherical collapse condition yield...
متن کاملConditional Mass Functions and Merger Rates of Dark Matter Halos in the Ellipsoidal Collapse Model
Analytic models based on spherical and ellipsoidal gravitational collapse have been used to derive the mass functions of dark matter halos and their progenitors (the conditional mass function). The ellipsoidal model generally provides a better match to simulation results, but there has been no simple analytic expression in this model for the conditional mass function that is accurate for small ...
متن کاملThe Large Scale Bias of Dark Matter Halos: Numerical Calibration and Model Tests
We measure the clustering of dark matter halos in a large set of collisionless cosmological simulations of the flat ΛCDM cosmology. Halos are identified using the spherical overdensity algorithm, which finds the mass around isolated peaks in the density field such that the mean density is ∆ times the background. We calibrate fitting functions for the large scale bias that are adaptable to any v...
متن کاملAre Galaxy Properties Only Determined by the Dark Matter Halo Mass?
Conditional luminosity function (CLF) of dark matter halos supersedes simple models on the number of galaxies as a function of the halo mass, or the so-called halo occupation number, by assigning a luminosity distribution to those galaxies. Suggestions have now been made that both the clustering strength and properties of hosted galaxies of a given dark matter halo depends also on the age and t...
متن کامل