Understanding Coherent Large Scale Modes in Power Spectra

[shirin]

Hi everyone,
I am reading a paper, which discusses about power spectrum. There is a plot which is power versus k(wave number). It says something about "coherent large scale modes". Would you please tell me what the meaning of this is?

 

[Chronos]

Cite the paper instead of a pinada

 

[shirin]

Sorry, I shouldn't have said "a paper". It is a note. I don't know what mode is in regard to power spectrum in Fourier space? Does it mean wavenumber? And in addition what "coherent mode" is?

 

[Drakkith]

Again, can you cite the paper you are reading? Perhaps even give us a link to it?

 

[bapowell]

Sorry, I shouldn't have said "a paper". It is a note. I don't know what mode is in regard to power spectrum in Fourier space? Does it mean wavenumber? And in addition what "coherent mode" is?

They are Fourier modes, which are the time-dependent functions in front of the plane wave basis states in the Fourier decomposition of a function. The mode functions are indexed by comoving wavenumber, k: they describe the time evolution of perturbations on the scale k.