I am seeking the SDSS data to reconstruct the Universe evolution. The problem I face is that for a given z (redshift), the position D(z) seems to be always presented in terms of models (L-CDM, Friedmann-Lemaitre equation, etc).
To make things more complicated, the z is oftentimes presented in terms of principal component analysis, that is, spectroscopic analysis is done using several template (which I suppose are spectral features).
My questions are:
a) Does the spectroscopic analysis fit a single z per galaxy (I suspect so).
b) Where is the raw data versus z versys spherical coordinates.
c) It seems that there is pre and post versions of the data. What kind of adjustment is being performed on it? Is this adjustment prior to model fitting or the adjustment already reflects the Inflation Model.
I was provided the following clues:
Paper describing data
https://arxiv.org/abs/1411.1074
This is where I understood the data is.
http://www.sdss.org/dr12/
Just plain ignorance. I was directed towards version 10.... I tried to update that advice and moved up to 12. I didn't know version 13 was complete.
My goal now is to get version 13 z (redshift), nz (number density - it seems that this parameter is a proxy to mass density, at least, that is how I would use it if galaxies masses were not widely available) and RA, DEC.
I would like to get the data that is model free, that is, that is not corrected using L-CDM..
This should be easy but there is so much information in the field, that is difficult to make data choices without making mistakes (version 12 would had been my first mistake).
Could you direct me towards the right dataset.
photoposPlate-dr-12.fits
specObj-dr12.fits
ssppOut-dr12.fits
ssppplates-dr12.fits
I would be forever indebted if you could confirm my decisions on recreating BAO calculations.
Thanks,
Marco
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