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[1004.2244] Regarding the Line-of-Sight Baryonic Acoustic F

Posted: April 19 2010
by Syksy Rasanen
This paper has more on the claimed measurement of the radial baryon acoustic oscillation signal mentioned at http://cosmocoffee.info/viewtopic.php?t=1301&highlight=.

The authors independently redo the analysis of Gaztanaga, Cabre and Hui, and obtain basically the same results as far as the data is concerned. However, they argue that the detection of the radial mode is not statistically significant, and discuss expected improvement from future surveys.

In particular, they claim that the model with the oscillation signal does not provide a fit to the data that would be decisively better than a completely featureless spectrum (their table 2 on the last page). This seems straightforward.

As for predictions for future surveys, I wonder about using [tex]\Lambda[/tex]CDM simulations to set error bars, given that the large-scale statistical properties of the observed distribution are different from those in simulations: http://cosmocoffee.info/viewtopic.php?t=1543&highlight= - see also 0903.0950.

[1004.2244] Regarding the Line-of-Sight Baryonic Acoustic F

Posted: April 19 2010
by Patrick McDonald
I think its safe to say that the people making this kind of projection based on simulations don't believe there is any real evidence for disagreement.
There is good reason for this. There are plenty of very reliable-seeming analyses on the relevant scales for these projections which show absolutely beautiful precision agreement between the theory and observations, e.g., recent SDSS power spectrum measurements by Percival and Reid. I, and I'm sure more direct experts in observational galaxy clustering, generally flip through papers making wild-sounding claims for disagreement, looking for signs of believability, and don't find anything to make me doubt the standard analyses. The present paper is a pretty good example - when the original claims about the radial BAO feature came out, lots of people were interested and looked into it, but pretty quickly figured out that the arguments supporting the claims were flawed. Especially if the authors have not *done their job* of self-refereeing and presenting results that are free of pretty elementary problems, I think most people decide they've already wasted too much time on the paper by the time they figure this out and don't want to waste more by writing public comments, although that unfortunately dooms lots of other people to making the same mistake.

[1004.2244] Regarding the Line-of-Sight Baryonic Acoustic F

Posted: April 19 2010
by Syksy Rasanen
Do you think that the papers on the statistics of the large-scale distribution (the fractal dimension analysis and other work mentioned in http://cosmocoffee.info/viewtopic.php?t=1543&highlight=) have elementary errors and lack believability? What do you think those errors are?