Nonlinear Effects in the Amplitude of Cosmological Density Fluctuations (2009)
Juszkiewicz, Roman, Feldman, Hume A., Fry, J. N., Jaffe, Andrew H.
The amplitude of cosmological density fluctuations, $\sigma_8$, has been studied and estimated by analysing many cosmological observations. The values of the estimates vary considerably between the...
Dark Matter Gravitational Clustering With a Long-Range Scalar Interaction (2008)
Hellwing, Wojciech A., Juszkiewicz, Roman
We explore the possibility to improve the $\Lambda$CDM model at megaparsec scales by introducing a scalar interaction which increases the mutual gravitational attraction of dark matter particles....
A new method of measuring the cluster peculiar velocity power spectrum (2008)
Zhang, Pengjie, Feldman, Hume A., Juszkiewicz, Roman, Stebbins, Albert
We propose to use spatial correlations of the kinetic Sunyaev-Zeldovich (KSZ) flux as an estimator of the peculiar velocity power spectrum. In contrast with conventional techniques, our new method...
A new method of measuring the peculiar velocity power spectrum (2004)
Zhang, Pengjie, Stebbins, Albert, Juszkiewicz, Roman, Feldman, Hume
We show that by directly correlating the cluster kinetic Sunyaev Zeldovich (KSZ) flux, the cluster peculiar velocity power spectrum can be measured to $\sim 10%$ accuracy by future large sky coverage...
An estimate of \Omega_m without priors (2003)
Feldman, Hume A., Juszkiewicz, Roman, Ferreira, Pedro, Davis, Marc, Gaztanaga, Enrique, Fry, James N., ...
Using mean relative peculiar velocity measurements for pairs of galaxies, we estimate the cosmological density parameter $\Omega_m$ and the amplitude of density fluctuations $\sigma_8$. Our results...
The transition to nonlinearity and new constraints on biasing (2000)
Juszkiewicz, Roman, Gaztanaga, Enrique
We present two new dynamical tests of the biasing hypothesis. The first is based on the amplitude and the shape of the galaxy-galaxy correlation function, $\xi_g(r)$, where $r$ is the separation of...
Skewness as a probe of non-Gaussian initial conditions (2000)
Durrer, Ruth, Juszkiewicz, Roman, Kunz, Martin, Uzan, Jean-Philippe
We compute the skewness of the matter distribution arising from non-linear evolution and from non-Gaussian initial perturbations. We apply our result to a very generic class of models with...
Caldwell, R. R., Juszkiewicz, Roman, Steinhardt, Paul J., Bouchet, Francois
We propose a simple and accurate method for computing analytically the mass correlation function for cold dark matter and scale-free models that fits N-body simulations over a range that extends from...
Dynamics of pairwise motions (1998)
Juszkiewicz, Roman, Springel, Volker, Durrer, Ruth
We derive a simple closed-form expression, relating $\vs(r)$ -- the mean relative velocity of pairs of galaxies at fixed separation $r$ -- to the two-point correlation function of mass density...
Skewed exponential pairwise velocities from Gaussian initial conditions (1998)
Juszkiewicz, Roman, Fisher, Karl B., Szapudi, Istvan
Using an Eulerian perturbative calculation, we show that the distribution of relative pairwise velocities which arises from gravitational instability of Gaussian density fluctuations has asymmetric...
Previrialization: Perturbative and N-Body Results (1995)
Lokas, Ewa L., Juszkiewicz, Roman, Bouchet, Francois R., Hivon, Eric
We present a series of N-body experiments which confirm the reality of the previrialization effect. We also use weakly nonlinear perturbative approach to study the phenomenon. These two approaches...
Kurtosis of Large-Scale Cosmic Fields (1994)
Lokas, Ewa Luiza, Juszkiewicz, Roman, Weinberg, David, Bouchet, Francois
An attractive and simple hypothesis for the formation of large-scale structure is that it developed by gravitational instability from primordial fluctuations with an initially Gaussian probability...
Nonlinear Effects in the Amplitude of Cosmological Density Fluctuations
Roman Juszkiewicz, Hume A. Feldman, J. N. Fry, Andrew H. Jaffe
The amplitude of cosmological density fluctuations, σ8, has been studied and estimated by analysing many cosmological observations. The values of the estimates vary considerably between the various...