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--- courses:ast403:baryon-acoustic-oscillation [2026/04/04 01:15] – shuvo
+++ courses:ast403:baryon-acoustic-oscillation [2026/04/06 09:58] (current) – [Observational Signatures: The Standard Ruler] shuvo
@@ Line 12: / Line 12: @@
 **Photon-Baryon Fluid:** Electrons and photons were tightly coupled via Thomson scattering, and protons were coupled to electrons via Coulomb interactions. This created a single, relativistic photon-baryon fluid.
-When a dark matter overdensity collapsed under gravity, it pulled the photon-baryon fluid with it. However, the immense radiation pressure of the photons strongly resisted this compression, driving the fluid outward. This competition between gravity and radiation pressure generated spherical acoustic waves propagating away from the initial overdensities.
+When a dark matter overdensity collapsed under gravity, it pulled the photon-baryon fluid with it. However, the immense radiation pressure of the photons strongly resisted this compression, driving the fluid outward. **This competition between gravity and radiation pressure generated spherical acoustic waves propagating away from the initial overdensities.**
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 [{{ :courses:ast403:desi_bao.jpg?600 | Fig 3: Large-scale structure from DESI redshift survey}}]
+An animation of the formation of BAO: [[https://www.youtube.com/watch?v=jpXuYc-wzk4]]