Publication Abstracts

Canuto 1976

Canuto, V., 1976: Inhomogeneities in the early universe. Astrophys. J., 205, 659-673, doi:10.1086/154322.

In big-bang cosmology it is traditional to assume that before decoupling, matter was so tightly bound to radiation as to be prevented from forming any permanent structure. In particular, galaxies were difficult to form before tD.

It is the goal of this paper to point out that the previous arguments are based on linearized theories for both radiation and matter, as well as for their interaction, and that if nonlinear effects are taken into account, the situation can change considerably.

For matter, we shall present several nonlinear Lagrangians and discuss in particular the salient features of the most typical equation describing nonlinear phenomena, the Kortewegde-Vries (KdV) equation, and the existence among its solutions of solitons, self-bound packets of energy. We shall then present our first model, based on the possibility of creating a cascade of solitons from an initial perturbation. We shall show how an initial soliton can, through the nonlinear action of the terms contained in the KdV equation, fragment into many others, the number of them being proportional to the amplitude of the original one.

We shall then discuss our second model, based on the interaction of matter with an intense radiation field. For the electromagnetic field, we shall discuss the Euler-Heisenberg nonlinear Lagrangian, and the changes in the refractive index of the medium.

Lacking a general description for the nonlinear interaction of matter and radiation, we shall limit ourselves to the case of matter interacting with an almost monochromatic photon gas. It will be shown that an effective mechanism exists whereby radiation and matter do not mix, if the radiation field has a nonuniform intensity, i.e., ∇I(r) ≠ 0. The matter so separated from radiation behaves independently of the surrounding radiation.

It is also shown that the conditions are appropriate for the interface between matter and radiation to become unstable and for a turbulent layer to form. After the previous arguments are translated into the proper cosmological framework, we propose to interpret the portions of matter so isolated as being closely related to the delayed cores forming the core of protogalaxies.

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BibTeX Citation

@article{ca00020i,
  author={Canuto, V.},
  title={Inhomogeneities in the early universe},
  year={1976},
  journal={Astrophys. J.},
  volume={205},
  pages={659--673},
  doi={10.1086/154322},
}

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RIS Citation

TY  - JOUR
ID  - ca00020i
AU  - Canuto, V.
PY  - 1976
TI  - Inhomogeneities in the early universe
JA  - Astrophys. J.
VL  - 205
SP  - 659
EP  - 673
DO  - 10.1086/154322
ER  -

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