Image:Structure mode history.svg

From Wikipedia, the free encyclopedia

• Image
• File history
• File links

[edit] Summary

This is my work, calculated using a code I wrote myself, plotted in Gnuplot and edited in Adobe Illustrator.

This figure depicts two linear modes during the formation of structure in our universe. The two modes have the same wavelength. The dashed line is a cold dark matter (CDM) mode and the solid line is a baryon mode. The modes enter the (Hubble) horizon volume during radiation domination. The evolution of the modes up to this point is not very important, as it looks different for different choices of gauge. Upon horizon entry the baryonic mode is coupled to the baryon-radiation fluid, and oscillates as pressure prevents overdensities from collapsing below the Jeans mass. The CDM mode grows logarithmically during radiation domination. At matter-radiation equality the CDM mode begins to grow more quickly. At subsequent decoupling of radiation from the baryons (and consequent enormous drop in the Jeans mass for baryons), baryons start falling into the gravitational potentials established by the CDM, and the baryonic mode begins to closely mimic the CDM mode. This figure thus illustrates the pivotal importance of CDM for structure formation. Horizon entry and decoupling are marked at the top of the figure.

The calculation was performed for current best-fit values of the Lambda-CDM model. The mode has wavelength exactly one-thousandth the Hubble radius today, or approximately 4.2 Mpc. The figure includes all linear physics except that decoupling is treated as an instantaneous process occurring at redshift 1100. The basic formalism used to compute all this can be found in T. Padmanabhan, Structure formation in the universe (cited in physical cosmology).

[edit] Licensing

I, the copyright holder of this work, hereby publish it under the following licenses: Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. Subject to disclaimers. This file is licensed under the Creative Commons Attribution-ShareAlike license versions 2.5, 2.0, and 1.0. You may select the license of your choice.

File history

Click on a date/time to view the file as it appeared at that time.

• Search for duplicate files
• Edit this file using an external application

  See the setup instructions for more information.

File links