| Authors: | Francesco Sylos Labini, Nikolay L. Vasilyev, Yurij V. Baryshev |
| Abstract: | One of the most striking features predicted by standard models of galaxy
formation is the presence of anti-correlations in the matter distribution at
large enough scales ($r>r_c$). Simple arguments show that the location of the
length-scale $r_c$, marking the transition from positive to negative
correlations, is the same for any class of objects as for the full matter
distribution, i.e. it is invariant under biasing. Considering several
main-galaxy and luminous-red-galaxy volume-limited samples of the Sloan Digital
Sky Survey Data Release 7, we measure, with the standard methods, that the
redshift-space galaxy two-point correlation function remains positive at scales
$>250$ Mpc/h, while in the concordance LCDM it should be negative beyond
$r_c\approx 120$ Mpc/h. However we show that the large scale behavior of
$\xi(r)$ is affected by systematic volume-dependent effects which make the
detection of correlations to be only an estimate of a lower limit of their
amplitude, spatial extension and statistical errors. We also show that because
of the same systematic effects, the scale signaling the real space counterpart
of the baryon acoustic oscillations is located, if present at all, at scales
larger than 250 Mpc/h. These results are challenging for any model of structure
formation. |
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Mark Wyman
Joined: 13 Jan 2009
Posts: 3
Affiliation: Perimeter Institute
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 Posted: March 12 2009 |
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| These authors claim there is no evidence for BAO in the galaxy correlation functions they compute using the SDSS DR7. Is there some obvious reason why it would be missing from the way they calculate galaxy correlation functions? |
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Anze Slosar
Joined: 24 Sep 2004
Posts: 205
Affiliation: Brookhaven National Laboratory
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| Posted: March 12 2009 |
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If you look at fig. 3 of
astro-ph/0501171
the data is positive, but consistent with theory at distance 100−200 Mpc. The same is actually also true if you look at Labini et al figure 2, blue points. I am quite confident that Eisenstein knows what he's doing and the data haven't improved that much in the past 3 years...
I haven't read the paper, but I would be surprised they could measure xi at distances >200 Mpc/h with the errorbars they claim! Pink points on their fig2 have errorbars at 300 the same size as errrobars at 80... |
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