Mock Gravity and Cosmic Structure
Abstract
The process of generating largescale cosmic structure from the radiationpressure or "mock gravity" instability is studied with particular emphasis on the implications of the BerkeleyNagoya rocket data for the submillimeter background (SMB). The linear theory of perturbations in an absorbing medium embedded in an expanding universe of radiation sources is presented, including the effect of an inhomogeneous luminosity density or opacity. The instability sets up collapse velocities in linear perturbation theory which far exceed those from gravitational instability, so growth continues even after the instability switches off. Perturbation growth due to this "coasting effect" is analyzed and related to the growth of largescale cosmic structures at recent times; largescale structure is shown to evolve very little from 1 + z ~ 5 to the present. Nonlinear smallscale effects of the instability are analyzed; it is shown that radiation pressure would compress gas into small, dense pressureconfined clouds with τ >> 1, which leads to a substantial atomic continuum opacity and consequently a stronger linear instability. However, the range of the instability is limited by optical depth; it only operates on large scales (2π/k_1_ ~ 40h^1^_50_ Mpc) if the gas density is low ({OMEGA}_g_ <~ 10^2^). A nonlinear selfsimilar bubble "attractor" solution is described which grows to a comoving diameter of more than 40hs^1^_50_ Mpc for a wide range of initial conditions and can in principle reach a maximum diameter of 180h^1^_50_ Mpc by the present epoch. Linear theory is used to estimate anisotropy in background radiation. Doppler scattering typically produces anisotropy comparable to current 1.5 cm limits on arcminute scales. A search for subarcminute fluctuations in the SMB at short wavelengths (~ 1 mm) should reveal fluctuations of much larger amplitude, δT/T ~ 10^3^, due to dust optical depth fluctuations.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 1989
 DOI:
 10.1086/167371
 Bibcode:
 1989ApJ...340....1H
 Keywords:

 Cosmology;
 Gravitation Theory;
 Relic Radiation;
 Galactic Clusters;
 Perturbation Theory;
 Radiation Distribution;
 Radiation Pressure;
 Strange Attractors;
 Astrophysics;
 COSMIC BACKGROUND RADIATION;
 COSMOLOGY;
 EARLY UNIVERSE;
 GALAXIES: CLUSTERING;
 GRAVITATION