Why Does Increased Baryon Loading Shift Power Spectrum to Higher Multipoles?

[gluon]

About the power spectrum: if increased the number of baryons the frequency of the oscillation reduced.I want to ask why this fact moves the power spectrum to higher multipoles and no to smaller?smaller frequency doesn't mean longer wavelength and thus smaller multipoles?

 

[bapowell]

Adding baryons also decreases the sound speed and so decreases the size of the sound horizon. Since the sound horizon sets the wavelength of the fundamental mode, the peaks shift to higher-\ell (or smaller wavelength).