Search

Here follows a preliminary report on the construction of fake millimeter and submillimeter skies, as observed by virtual instruments, e.g. the COBRA/SAMBA mission, using theoretical modeling and data extrapolations. Our goal is to create maps as realistic as possible of the relevant physical contributions which may contribute to the detected signals. This astrophysical modeling is followed by simulations of the measurement process itself by a given instrumental configuration. This will enable a precise determination of what can and cannot be achieved with a particular experimental configuration, and provide a feedback on how to improve the overall design. It is a key step on the way to define procedures for the separation of the different physical processes in the future observed maps. Note that this tool will also prove useful in preparing and analyzing current (e.g. balloon borne) Microwave Background experiments.

The spatial two point galaxy correlation function, ξ(r), is, at present, the most useful statistic for comparing theoretical models to observational data. We have derived an expression for the dynamical evolution of ξ for structures arising from Gaussian initial conditions under the assumption that non-linear evolution may be described by the Zel’dovich approximation. The observed angular correlation function of galaxies, ω(θ), may place useful constraints on the spectrum of initial fluctuations on large scales. The angular correlation function due to the growth of structure from Gaussian fluctuations with the Cold Dark Matter spectrum is calculated. It is shown that ω g for the Ω = 1 biassed CDM model exhibits a gentle falloff near the position of the break found by Groth and Peebles in the Shane-Wirtanen catalogue.

We classify massive stable collisionless relics of the Big Bang into three categories of dark matter: hot, with damping mass about supercluster scale; warm, with damping mass of galactic or cluster scale; and cold, with negligible damping. The first objects that form in universes dominated by hot and warm relics are pancakes. Coupled one-dimensional N-body and Eulerian hydrodynamical simulations follow the nonlinear evolution of pancakes, the separation of baryons from dark matter via shock formation and the evolution of the shocked gas by conduction as well as by cooling. We sketch a simple analytic theory based upon the uniformity of pressure over the shocked region which accurately describes our numerical results. Only ∼10–20% of the gas cools sufficiently to fragment on sub-galactic scales in neutrinodominated (hot relic) theories. Cooling is efficient for warm relics. In all cases, the typical fragment size is ∼109–1010 M⊙.

The pancake picture with massive neutrinos has a nonlinear mass scale for dark matter different from that inferred from the galaxy autocorrelation function. In the first part of this paper, we suggest ways in which the correlation function for mass density may differ from that of galaxies. In the second part, we predict the magnitude of the Zeldovich-Sunyaev effect arising from pancakes. Electrons in the hot gas created by pancake shocks can upscatter photons in the microwave background radiation, causing spectral distortions. Angular differences in these distortions lead to temperature fluctuations which are on the edge of observability, and can be used as a test of the pancake scenario.

Some cosmological implications of the recently discovered submillimeter background (SMB) are discussed. Opacity and isotropy arguments show that if the background is due to dust emission it must originate at a high redshift z ≳ 10. Isotropy measurements are used to constrain the amplitude of dust optical-depth fluctuations and hence the scale of dust inhomogeneity. It is shown that the comoving scale of (δρ/ρ) ≃ 1 fluctuations in dust was likely no larger than ~ 3h-1 Mpc when the background was generated. The observed flux, the inferred high z and high opacity imply that on small scales the mock gravitational instability driven by radiation pressure may have dominated gravitational effects.

A ‘Very Massive Object’, henceforth referred to as a VMO, is defined to be a star that goes pair unstable during its oxygen burning phase. This means that it must have an initial mass in the range 102–105 MƟ. The evolution of such a star, in both its hydrogen and helium burning phase (when it is subject to rapid mass loss) and its unstable oxygen burning phase has been summarized in an accompanying talk (Bond, Arnett and Carr 1982). The important qualitative conclusion is that oxygen cores with mass larger than about 102 MƟ collapse entirely to black holes, whereas oxygen cores smaller than this disrupt. The critical dividing mass MƟ associated with the precursor hydrogen star would lie in the range 200–500 MƟ, the large uncertainty reflecting our ignorance of how much mass loss occurs during the hydrogen and helium burning phase.

We show that the angular correlation function of galaxies, w gg (θ), may be used as a direct test of large scale power in cosmic density fluctuation spectra. Groth and Peebles (1986) found a break in w(θ) from a power-law at θ ∼ 3° in an analysis of the Shane-Wirtanen galaxy counts. Maddox and Efstathiou (1987) find evidence for a similar break in w(θ) in the Southern Sky Survey. Testing for a break is a powerful probe of the linear regime of fluctuation spectra. The CDM model has such a break; almost all candidate Gaussian theories with enough large scale power to explain the clustering of clusters do not.