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From: Héctor Aceves <aceves_at_astro.unam.mx>

Date: Sat, 29 Jun 2013 16:50:47 -0700

Hi...

*>
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*> I have a couple of questions in this topic, sorry for the inconveniences.
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*> Comments are welcomed.
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*>
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*> First, I am a bit confused by the comment: "Right. (And note that the
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*> code will use P'(k) = k^(PrimordialIndex-1) * P(k) as actual power spectrum
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*> for
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*> the ICs, and this is also what's appearing then in inputspec_ics.txt) "
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*> [...V. Springel]
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*>
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*> Say I have a tabulated spectrum P(k) from CAMB at z=49, properly normalized
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*> to the standard definition of Sig8 (say to 0.816 at z=0) and where I used
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*> as input parameter the spectral index 0.968, that I plan to use in N-GenIC
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*> with ReNormalizeInputSpectrum=0. I understand that the P(k) from CAMB is
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*> the P'(k) [P prime] you indicate above, isn't? So one just has to provide
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*> in the tabulated file two columns "log k , log [ 4 Pi k^3 P(k)]" with P(k)
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*> being the one -for example- from CAMB, isn't?
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*>
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*> Secondly, by using the option given in the input parameter file for
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*> N-GenIC:
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*> InputSpectrum_UnitLength_in_cm 3.085678e24 ; one can safely input the
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*> wave-number k in [h/Mpc] units directly from CAMB, isn't?
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*>
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*>
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*> Thirdly.. when one uses ReNormalizeInputSpectrum=0, all the sigma^2
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*> definitions appear irrelevant in this case, isn't? Since I understand that
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*> the Sigma computation is for normalization purposes essentially. In any
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*> case, I assume one can compute Sigma directly from the initial snapshot,
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*> after obtaining its power spectrum directly from the data, and compare it
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*> to the expected value.
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*>
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*> Thanks for your time and patience :-)
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*>
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*> -Hector
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*>
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*>
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*> On Fri, Jun 28, 2013 at 7:29 AM, Volker Springel <
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*> volker_at_mpa-garching.mpg.de
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*> > wrote:
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*>
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*> > >> Right. (And note that the code will use P'(k) = k^(PrimordialIndex-1)
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*> *
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*> > P(k) as actual power spectrum for the ICs, and this is also what's
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*> > appearing then in inputspec_ics.txt)
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*> > >>
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*>
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*>
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Received on 2013-06-30 02:20:43

Date: Sat, 29 Jun 2013 16:50:47 -0700

Hi...

Received on 2013-06-30 02:20:43

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