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Exploring Plasma's Influence on Large Scale Structure Formation in Cosmology

This week's discussion focused on the impact of plasma on large-scale structure formation in the universe. We reviewed Dodelson's book and Pisin's paper, “Plasma Suppression of Large Scale Structure Formation in the Universe.” Key topics highlighted include the introduction of plasma effects, evolution of baryon perturbations, and the resulting matter power spectrum. We delve into concepts such as Debye shielding, Landau damping, and the modified baryon perturbation equation to understand how plasma influences density perturbations and sound speed.

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Exploring Plasma's Influence on Large Scale Structure Formation in Cosmology

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  1. Weekly Report 08.28R97222004蔡偉駿

  2. This Week Discussing with Feng-Ying about code. Read Dodelson’s book Ch.7 Read Pisin’s Paper “Plasma Suppression of Large Scale Structure Formation in the Universe”, and I’ll report it briefly.

  3. Pisin’s Plasma Paper Outline • Introduction • Plasma effect • Evolution of baryon perturbation • Matter power spectrum • Result

  4. Introduction Our aim is to seethe influence of plasma on : (1) Jean’s length and sound speed (2) Density perturbation equation (3) Power spectrum

  5. Plasma Effect What is plasma ? → A partially ionized gas which is approximately neutral Plasma state of the universe : (1) Pre-recombination (2) Post-reionization → It’s what we consider

  6. Plasma Effect • Debye shielding • Landau damping → Energy exchange between particles and wave • Finite temperature →Residual electric field

  7. Evolution of baryon perturbation • Modified baryon perturbation equation : where , , term is the contribution of residual E. field

  8. Evolution of baryon perturbation • Solving the equation (1) (a) Initial perturbation : by adiabatic condition , “ * ” means reionization (b) By thermodynamics and plasma physics (c) By Fourier Transform and (b), (1) becomes

  9. Evolution of baryon perturbation Solving the equation (1) (d) To solve eq(2) for a given k-mode, we must know the relationship between Jean’s scale( ) and expansion factor By adiabatic expansion and matter dominate and ,

  10. Evolution of baryon perturbation Solving the equation (1) (e) There are three regimes of k-mode to discuss Gravity dominates : linear growth plasma oscillation dominates : oscillates

  11. Evolution of baryon perturbation • Solving the equation (1) (f) Two kinds of solutions ：

  12. Matter power spectrum • Modified power spectrum ：Transfer function ：Growth function ：Modified Growth function

  13. Matter power spectrum

  14. Result

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