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Arxiv New Filter | Bookmarks & clubs | Arxiv ref/author:

Sachs-Wolfe and Doppler Transfer Functions
 
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Muhammad Junaid



Joined: 05 Jan 2017
Posts: 7
Affiliation: University of Alberta

PostPosted: January 06 2017  Reply with quote

I have been using your 'Camb' code to calculate transfer functions for my research. I am interested in calculation of TSW(k) and TD(k) where these are Sachs-Wolfe and Doppler terms as given in Eq. (7.3.58) DAMPT lectures on cosmology (http://www.damtp.cam.ac.uk/user/db275/Cosmology2015.pdf) so can you help me with that.

I also wanted to know the units of Camb code output velocity transfer functions vel / k2 and if one multiplies vel / k2 by k2 then what will be the units of vel Transfer functions 11, 12 13.
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Antony Lewis



Joined: 23 Sep 2004
Posts: 1273
Affiliation: University of Sussex

PostPosted: January 06 2017  Reply with quote

You can get individual terms for the sources by commenting appropriately the terms in output() in equations.f90. Doppler and ISW terms are already there (commented or not).

The transfer functions should be dimensionless (and normalized for unit initial superhorizon curvature perturbation).
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Muhammad Junaid



Joined: 05 Jan 2017
Posts: 7
Affiliation: University of Alberta

PostPosted: January 06 2017  Reply with quote

So how can i access to value of Doppler term, as I have uncommented the code in output() but i don't see any new result in transfer_function output file. How can I output the doppler term in the transfer function output file.

Secondly, is there any way one can calculate the transfer function without the comoving perturbations \mathcal{R}_k part as in Eq. 7.3.58 of Dampt lectures, \Theta (k,\hat{n})= [T_{SW}(k)+i \cos(\theta)T_{D}(k)] \mathcal{R}_k, as I just need TD and TSW. You see, I calculate the power spectrum for the comoving perturbations using my own model (code) and I only need the TSW and TD part of the transfer functions.
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