Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The cosmological bulk flow: consistency with $\Lambda$CDM and $z\approx
  0$ constraints on $\sigma_8$ and $\gamma$   We derive estimates for the cosmological bulk flow from the SFI++
Tully-Fisher (TF) catalog. For a sphere of radius $40 \hmpc$ centered on the
MW, we derive a bulk flow of $333 \pm 38\kms $ towards Galactic $
(l,b)=(276^\circ,14^\circ)$ within a $3^\circ$ $1\sigma$ error. Within a $
100\hmpc$ we get $ 257\pm 44\kms$ towards $(l,b)=(279^\circ, 10^\circ)$ within
a $6^\circ$ error. These directions are at a $40^\circ$ with the Supergalactic
plane, close to the apex of the motion of the Local Group of galaxies after the
Virgocentric infall correction. Our findings are consistent with the
$\Lambda$CDM model with the latest WMAP best fit cosmological parameters. But
the bulk flow allows independent constraints. For WMAP inferred Hubble
parameter $h=0.71$ and baryonic mean density parameter $\Omega_b=0.0449$, the
constraint from the bulk flow on the matter density $\Omega_m$, the
normalization of the density fluctuations, $\sigma_8$, and the growth index,
$\gamma$, can be expressed as
$\sigma_8\Omega_m^{\gamma-0.55}(\Omega_m/0.266)^{0.28}=0.86\pm 0.11$ (for
$\Omega_m\approx 0.266$). Fixing $\sigma_8=0.8$ and $\Omega_m=0.266$ as favored
by WMAP, we get $\gamma=0.495\pm 0.096$. The constraint derived here rules out
popular DGP models at more than the 99% confidence level. Our results are based
on a method termed \ace\ (All Space Constrained Estimate) which reconstructs
the bulk flow from an all space three dimensional peculiar velocity field
constrained to match the TF measurements. At large distances \ace\ generates a
robust bulk flow from the SFI++ that is insensitive to the assumed prior. For
comparison, a standard straightforward maximum likelihood estimate leads to
very similar results.

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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: math