Portal de Periódicos da CAPES

Generation of Density Perturbations by Primordial Magnetic Fields

1996; IOP Publishing; Volume: 468; Linguagem: Inglês

10.1086/177667

1538-4357

Eun‐jin Kim, Angela V. Olinto, R. Rosner,

Astronomy and Astrophysical Research

view Abstract Citations (126) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Generation of Density Perturbations by Primordial Magnetic Fields Kim, Eun-Jin ; Olinto, Angela V. ; Rosner, Robert Abstract We study the generation and evolution of density perturbations and peculiar velocities due to primordial magnetic fields. We assume that a random magnetic field was present before recombination and follow the field's effect on the baryon fluid starting at recombination. We find that magnetic fields generate growing density perturbations on length scales larger than the magnetic Jeans length, λ_B_ and damped oscillations for scales smaller than λ_B_. For small wavenumbers k (large length scales), We find that the magnetic field-induced density power spectrum generally scales as k^4^. We derive the magnetic Jeans length explicitly by including the back-reaction of the velocity field onto the magnetic field and by decomposing the magnetic field into a force-free background field and perturbations about it. Depending on the strength of the magnetic field and the ultraviolet cutoff of its spectrum, structure can be generated on small or intermediate scales early in the history of the universe. For a present rms magnetic field of 10^-10^ G on intergalactic scales, we find that perturbations on galactic scales could have gone nonlinear at z ~ 6. Finally, we discuss how primordial magnetic fields affect scenarios of structure formation with nonbaryonic dark matter. Publication: The Astrophysical Journal Pub Date: September 1996 DOI: 10.1086/177667 arXiv: arXiv:astro-ph/9412070 Bibcode: 1996ApJ...468...28K Keywords: COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; MAGNETOHYDRODYNAMICS: MHD; COSMOLOGY: THEORY; GALAXIES: FORMATION; MAGNETIC FIELDS; Astrophysics E-Print: Final version to appear ApJ, August 1996. Significant changes in the formal approach but similar conclusions. 47 pages, plain TeX, 3 figures available from olinto@fnalv.fnal.gov full text sources arXiv | ADS |