Edmund Bertschinger

Self - similar secondary infall and accretion in an Einstein-de Sitter universe

Similarity solutions have been found for secondary infall and accretion onto an initially overdense perturbation in an Einstein--de Sitter (..cap omega.. = 1) universe. After the initial collapse of a positive density perturbation, bound shells continue to turn around and fall in, with the radius of the shell currently turning around increasing as t/sup 8/9/ and the mass within this radius increasing as t/sup 2/3/. The secondary infall approaches a self-similar form, with the exact behavior depending on the kind of gas and on central boundary conditions. If there is a central black hole, it grows by accretion, with the density having the power-law form rhoproportionalr/sup 01.5/ near the center. If there is no central black hole, a rhoproportionalr/sup 02.25/ density profile results, with infalling matter added to successively larger radii.

Dynamics of radiative supernova remnants

A high-resolution numerical simulation is used to study the evolution of a SNR evolving in a homogeneous uniform medium. Emphasis is placed on the transition from the adiabatic stage to the radiative pressure-driven snowplow stage, along with the possible further establishment of a momentum-conserving snowplow state. In most cases the momentum-conserving snowplow is found to be delayed beyond the merger of the remnant with the interstellar medium. 39 references.

Second order power spectrum and nonlinear evolution at high redshift

The Eulerian cosmological fluid equations are used to study the nonlinear mode coupling of density fluctuations. We evaluate the second-order power spectrum including all four-point contributions. In the weakly nonlinear regime we find that the dominant nonlinear contribution for realistic cosmological spectra is made by the coupling of long-wave modes and is well estimated by second order perturbation theory. For a linear spectrum like that of the cold dark matter model, second order effects cause a significant enhancement of the high

Distinguishing Modified Gravity from Dark Energy

k

Cold dark matter. 1: The formation of dark halos

part of the spectrum and a slight suppression at low

Statistics of primordial density perturbations from discrete seed masses

k

On the growth of perturbations as a test of dark energy and gravity

near the peak of the spectrum. Our perturbative results agree well in the quasilinear regime with the nonlinear spectrum from high-resolution N-body simulations. We find that due to the long-wave mode coupling, characteristic nonlinear masses grow less slowly in time (i.e., are larger at higher redshifts) than would be estimated using the linear power spectrum. For the cold dark matter model at

Recovering the full velocity and density fields from large-scale redshift-distance samples

(1+z)=(20,10,5,2)

Potential, velocity, and density fields from redshift-distance samples: Application - Cosmography within 6000 kilometers per second

the nonlinear mass is about

Prescription for Successful Extended Inflation

(180,8,2.5,1.6)