A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model

Details A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model

Oct 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993apj...416..399s&link_type=abstract

Astrophysical Journal v.416, p.399

Astronomy and Astrophysics

Astronomy

36

Cosmology: Cosmic Microwave Background, Cosmology: Dark Matter, Cosmology: Diffuse Radiation, Cosmology: Large-Scale Structure Of Universe, Hydrodynamics, Methods: Numerical

Scientific paper

Using the CDM model as a testbed, we produce and analyze sky maps of fluctuations in the cosmic background radiation field due to Sunyaev-Zel'dovich effect, as well as those seen in X-ray background at 1 keV and at 2 keV. These effects are due to the shock heating of baryons in the nonlinear phases of cosmic collapses. Comparing observations with computations provides a powerful tool to constrain cosmological models.
We use a highly developed Eulerian mesh code with 1283 cells and 2 × 106 particles. Most of our information comes from simulations with box size 64 h-1 Mpc, but other calculations were made with L = 16 h-1 and L = 4 h-1 Mpc. A standard CDM input spectrum was used with amplitude defined by the requirement (ΔM/M)rms = 1/1.5 on 8 h-1 Mpc scales (lower than the COBE normalization by a factor of 1.6±0.4), with H0 = 50 km s-1 Mpc-1 and Ωb = 0.05. For statistical validity a large number of independent simulations must be run. In all, over 60 simulations were run from z = 20 to z = 0.
We produce maps of 50' x 50' with 1' effective resolution by randomly stacking along the past light cone for 0.02 ≤ z ≤ 10 appropriate combinations of computational boxes of different comoving lengths, which are picked from among different realizations of initial conditions. We also compute time evolution, present intensity pixel distributions, and the autocorrelation function of sky fluctuations as a function of angular scale.
Our most reliable results are obtained after deletion of bright sources having 1 keV intensity greater than 0.1 keV cm-2 sr-1 s-1 keV-1. Then for the Sunyaev-Zel'dovich parameter γ the mean and dispersion are [barγ, σ(γ)] = (4, 3) × 10-7 with a lognormal distribution providing a good fit for values of y greater than average. The angular correlation function (less secure) is roughly exponential with scale length ˜2'.5. For the X-ray intensity fluctuations, in units of keV s-1 sr-1 cm-2 keV-1 we find barIX1, X2 = (0.02, 0.006) and σX1, X2 = (0.06, 0.03). The pixel distribution is roughly a power law in the intermediate range -f(Ix)dIX ∝ I-1.8X dIX. Also in these cases the angular autocorrelation function is roughly exponential with decay angles of θ0;X1,X2 found to be 1'.6 and 1'.3 but probably below our numerical resolution of 1'.0 in fact. If we scale our results to the COBE normalization, y values increase by approximately a factor of 9 and X-ray intensity by a factor of 8 to give a (δT/T)rms,SZ = 3.5 × 10-6 on the 1'.0 scale and I1keV = 0.2 keV cm-2 sr-1 s-1 keV-1 with both making nontrivial contributions to the observed background radiation fields.

Affiliated with

Also associated with

No associations

Rating

A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1324749