arXiv subjects

I. Zehavi

Publications and source records attributed to I. Zehavi.

21 records · Page 2Linked to original sources

arXiv1999

Correlation Analysis of SFI Peculiar Velocities

We present results of a statistical analysis of the SFI catalog of peculiar velocities, a recently completed survey of spiral field galaxies with I-band Tully-Fisher distances (Haynes et al. 1999). The velocity field statistic utilized is the velocity correlation function, $ψ_1(r)$ (Gorski et al. 1989). The analysis is performed in redshift space, so as to circumvent potential ambiguities connected with inhomogeneous Malmquist bias corrections. The results from the SFI sample are compared with linear-theory predictions. We generate a large set of mock samples, extracted from N-body simulations, which are used to assess the reliability of our analysis and to estimate the associated uncertainties. Defining $η_8=σ_8Ω_0^{0.6}$, we find that the measured $ψ_1(r)$ implies a degenerate constraint in the $η_8-Γ$ plane, with $η_8=(0.3 +/- 0.1) (Γ/0.2)^{0.5}$, at the $2σ$ level, for the inverse Tully-Fisher (ITF) calibration presented in this paper. Model constraints are quite sensitive to the ITF calibration. The other ITF calibrations by Giovanelli et al. (1997) and da Costa et al. (1998) both give, for $Γ=0.2$, $η_8\simeq 0.6$ as the best-fitting value.

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arXiv1997

Large Scale Power Spectrum from Peculiar Velocities Via Likelihood Analysis

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 catalogs. It has been applied to generalized CDM models with and without COBE normalization. The robust result for all the models is a relatively high PS, with $P(k) Ω^{1.2} = (4.8 \pm 1.5) \times 10^3 (Mpc/h)^3$ at $k=0.1 h/Mpc$. An extrapolation to smaller scales using the different CDM models yields $σ_8 Ω^{0.6} = 0.88 \pm 0.15$. The peak is weakly constrained to the range $0.02 \leq k \leq 0.06 h/Mpc$. These results are consistent with a direct computation of the PS (Kolatt & Dekel 1996). When compared to galaxy-density surveys, the implied values for $β$ ($\equiv Ω^{0.6}/b$) are of order unity to within 25%. The parameters of the COBE-normalized, flat CDM model are confined by a 90% likelihood contour of the sort $Ωh_{50}^μn^ν= 0.8 \pm 0.2$, where $μ= 1.3$ and $ν= 3.4, 2.0$ for models with and without tensor fluctuations respectively. For open CDM the powers are $μ= 0.95$ and $ν= 1.4$ (no tensor fluctuations). A $Γ$-shape model free of COBE normalization yields only a weak constraint: $Γ= 0.4 \pm 0.2$.

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arXiv1996

`Comparing the Predicted Abell/ACO Cluster & the MarkIII Galaxy Density and Velocity Fields', Contribution to the Wide Field Spectroscopy Meeting held in Athens, 20-24 May 1996

We compare the predicted Abell/ACO cluster density and velocity fields, using linear theory, with that based on the MarkIII catalog and the POTENT machinery within 7000 km/sec. Both density & velocity fields are in good qualitative agreement indicating that apart from a linear biasing factor the optical Abell/ACO clusters do trace the underlying mass distribution quite well.

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