Tsafrir Kolatt

Learn More
We study the angular-momentum profiles of a statistical sample of halos drawn from a high-resolution N-body simulation of the ΛCDM cosmology. We find that the cumulative mass distribution of specific angular momentum j in a halo of mass M v is well fit by a universal function, M (< j) = M v µj/(j 0 + j). This profile is defined by one shape parameter (µ or(More)
We study dark-matter halo density profiles in a high-resolution N-body simulation of a ΛCDM cosmology. Our statistical sample contains ∼ 5000 haloes in the range 10 11 − 10 14 h −1 M ⊙ and the resolution allows a study of subhaloes inside host haloes. The profiles are parameterized by an NFW form with two parameters, an inner radius r s and a virial radius(More)
Blood oxygenation level dependence (BOLD) imaging under either hypercapnia or hyperoxia has been used to study neuronal activation and for assessment of various brain pathologies. We evaluated the benefit of a combined protocol of BOLD imaging during both hyperoxic and hypercapnic challenges (termed hemodynamic response imaging (HRI)). Nineteen healthy(More)
We investigate several approaches for constructing Monte Carlo realizations of the merging history of virialized dark matter halos (" merger trees ") using the extended Press-Schechter formalism. We describe several unsuccessful methods in order to illustrate some of the difficult aspects of this problem. We develop a practical method that leads to the(More)
In this paper, we address the problem of fully automated decomposition of hyperspectral images for transmission light microscopy. The hyperspectral images are decomposed into spectrally homogeneous compounds. The resulting compounds are described by their spectral characteristics and optical density. We present the multiplicative physical model of image(More)
We present an improved version of the POTENT method for reconstructing the velocity and mass density fields from radial peculiar velocities, test it with mock catalogs , and apply it to the Mark III Catalog of Galaxy Peculiar Velocities. The method is improved in several ways: (a) the inhomogeneous Malmquist bias is reduced by grouping and corrected(More)
We use N-body simulations combined with semi-analytic models to compute the clustering properties of modeled galaxies at z ∼ 3, and confront these predictions with the clustering properties of the observed population of Lyman-break galaxies (LBGs). Several scenarios for the nature of LBGs are explored, which may be broadly categorized into models in which(More)
This paper introduces the formalism for the connection between rotation measure (RM) measurements for extragalactic sources and the cosmological magnetic field power spectrum. It is shown that by using a few hundred radio sources, for which Faraday RMs are available, the amplitude and shape of the cosmological magnetic field power spectrum are constrained.(More)
The power spectrum (PS) of mass density fluctuations, independent of " biasing " , is estimated from the Mark III catalog of peculiar velocities using Bayesian statistics. A parametric model is assumed for the PS, and the free parameters are determined by maximizing the probability of the model given the data. The method has been tested using detailed mock(More)