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...
Probing Dark Matter Substructure with Pulsar Timing (2007)
Siegel, E. R., Hertzberg, M. P., Fry, J. N.
We demonstrate that pulsar timing measurements may potentially be able to detect the presence of dark matter substructure within our own galaxy. As dark matter substructure transits near the...
Can Electric Charges and Currents Survive in an Inhomogeneous Universe? (2006)
Although observations point to the neutrality and lack of currents on large scales in the universe, many mechanisms are known that can generate charges or currents during the early universe. We...
Cosmological Structure Formation Creates Large-Scale Magnetic Fields (2006)
This paper examines the generation of seed magnetic fields due to the growth of cosmological perturbations. In the radiation era, different rates of scattering from photons induce local differences...
Effects of Inhomogeneities on Cosmic Expansion (2005)
We evaluate the effect of inhomogeneity energy on the expansion rate of the universe. Our method is to expand to Newtonian order in potential and velocity but to take into account fully nonlinear...
A Thermal Graviton Background from Extra Dimensions (2005)
Inflationary cosmology predicts a low-amplitude graviton background across a wide range of frequencies. This Letter shows that if one or more extra dimensions exist, the graviton background may have...
Nonlinear Kinetic Sunyaev-Zeldovich Effect (2001)
We derive fully nonlinear expressions for temperature fluctuations from the kinetic Sunyaev-Zeldovich (SZ) effect, the scattering of cosmic microwave background photons off hot electrons in bulk...
Feldman, Hume A., Frieman, Joshua A., Fry, J. N., Scoccimarro, Roman
We compute the bispectrum for the \IRAS PSCz catalog and find that the galaxy distribution displays the characteristic signature of gravity. Assuming Gaussian initial conditions, we obtain galaxy...
What Does It Take to Stabilize Gravitational Clustering? (2000)
An analytical understanding of the strongly nonlinear regime of gravitational collapse has been difficult to achieve. The only insight has been the stable clustering hypothesis, which assumes that...
The Bispectrum of IRAS Galaxies (2000)
Scoccimarro, R., Feldman, H. A., Fry, J. N., Frieman, J.
We compute the bispectrum for the galaxy distribution in the IRAS QDOT, 2Jy, and 1.2Jy redshift catalogs for wavenumbers 0.05
We present an analytic model for the fully nonlinear power spectrum P and bispectrum Q of the cosmological mass density field. The model is based on physical properties of dark matter halos, with the...
We investigate the nonlinear two- and three-point correlation functions of the cosmological density field in Fourier space and test the popular hierarchical clustering model, that the three-point...
Projection and Galaxy Clustering Fourier Spectra (1999)
Second order perturbation theory predicts a specific dependence of the bispectrum, or three-point correlation function in the Fourier transform domain, on the shape of the configuration of its three...
Large-scale structure and the redshift-distance relation (1998)
In efforts to demonstrate the linear Hubble law v = Hr from galaxy observations, the underlying simplicity is often obscured by complexities arising from magnitude-limited data. In this paper we...
Non-Linear Evolution of the Bispectrum of Cosmological Perturbations (1997)
Scoccimarro, Roman, Colombi, Stephane, Fry, J. N., Frieman, Joshua A., Hivon, Eric, Melott, Adrian
The bispectrum, the three-point function of density fluctuations in Fourier space, is the lowest order statistic that carries information about the spatial coherence of large-scale structures. For...
Fry, J. N., Melott, Adrian L., Shandarin, Sergei F.
We examine the effect of a threshold bias on the power spectrum and the bispectrum in an ensemble of numerical simulations (Gaussian initial perturbations with power law spectra P(k) \sim k^n, n=+1,...
Redshift distortions of galaxy correlation functions (1993)
Fry, J. N., Gaztanaga, Enrique
To examine how peculiar velocities can affect the 2-, 3-, and 4-point redshift correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize redshift...
Biasing and Hierarchical Statistics in Large-scale Structure (1993)
Fry, J. N., Gaztanaga, Enrique
In the current paradigm there is a non-trivial bias expected in the process of galaxy formation. Thus, the observed statistical properties of the galaxy distribution do not necessarily extend to the...
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...