How is the Power Spectrum of Matter Density Field Defined?

Click For Summary
The power spectrum of the matter density field is defined by the equation P_{xx}(k)=(2\pi^3)\delta(k-k^\prime)<x(k)x(k^\prime)>, which incorporates a factor of (2\pi^3). An alternative definition is presented as P_{yy}(k)=\delta(k-k^\prime)<y(k)y(k^\prime)>, which raises the question of whether the (2\pi^3) factor has been absorbed into the correlation function in this context. The discussion highlights the importance of understanding the role of these constants in the definitions of power spectra. Clarifying these definitions is crucial for accurate interpretations in cosmological studies. Overall, the relationship between the two equations is central to the analysis of matter density fields.
SherLOCKed
Messages
13
Reaction score
1
Homework Statement
The definition of power spectrum of matter density field is given by eq (1). I have also seen definitions of power spectra given by eq (2) . Does this mean ##(2\pi^3)## has been absorbed in the correlation function?
Relevant Equations
##P_{xx}(k)=(2\pi^3)\delta(k-k^\prime)\langle x(k)x(k^\prime)\rangle##

##P_{yy}(k)=\delta(k-k^\prime)\langle y(k)y(k^\prime)\rangle##

<Mentor: edit latex>
The definition of power spectrum of matter density field is given by eq(1). I have also seen definitions of power spectra given by eq(2) . Does this mean (2\pi^3) has been absorbed in the correlation function?

$$P_{xx}(k)=(2\pi^3)\delta(k-k^\prime)<x(k)x(k^\prime)>$$ .. (1)
$$P_{yy}(k)=\delta(k-k^\prime)<y(k)y(k^\prime)> $$.. (2)
 
Last edited:
Physics news on Phys.org
You need two hashes (inline) or two dollars to delimit your Latex.
 
(a) The polarisation pattern is elliptical with maximum (1,1) and minimum (-1,-1), and anticlockwise in direction. (b) I know the solution is a quarter-wave plate oriented π/4, and half-wave plate at π/16, but don't understand how to reach there. I've obtained the polarisation vector (cos π/8, isin π/8) so far. I can't find much online guidance or textbook material working through this topic, so I'd appreciate any help I can get. Also, if anyone could let me know where I can get more...

Similar threads

Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
15
Views
3K
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
1
Views
2K