For refcode 2010ApJ...709..483L: Retrieve 8 NED objects in this reference. Please click here for ADS abstract
NED Abstract
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2010ApJ...709..483L
Cosmic Flow From Two Micron AllSky Redshift Survey: the Origin of Cosmic
Microwave Background Dipole and Implications for {LAMBDA}CDM Cosmology
Lavaux, Guilhem; Tully, R. Brent; Mohayaee, Roya; Colombi, Stephane
Abstract. We generate the peculiar velocity field for the Two Micron
AllSky Redshift Survey (2MRS) catalog using an orbitreconstruction
algorithm. The reconstructed velocities of individual objects in 2MRS are
well correlated with the peculiar velocities obtained from highprecision
observed distances within 3000 km s^1^. We estimate the mean matter
density to be {OMEGA}_m_ = 0.31 +/ 0.05 by comparing observed
to
reconstructed velocities in this volume. The reconstructed motion of the
Local Group in the rest frame established by distances within 3000 km
s^1^ agrees with the observed motion and is generated by fluctuations
within this volume, in agreement with observations. Having tested our
method against observed distances, we reconstruct the velocity field of
2MRS in successively larger radii, to study the problem of convergence
toward the cosmic microwave background (CMB) dipole. We find that less
than half of the amplitude of the CMB dipole is generated within a volume
enclosing the HydraCentaurusNorma supercluster at around 40 h ^1^ Mpc.
Although most of the amplitude of the CMB dipole seems to be recovered by
120 h ^1^ Mpc, the direction does not agree and hence we observe no
convergence up to this scale. Due to dominant superclusters such as
Shapley or HorologiumReticulum in the southern hemisphere at scales above
120 h ^1^ Mpc, one might need to go well beyond 200 h ^1^ Mpc to fully
recover the dipole vector. We develop a statistical model which allows us
to estimate cosmological parameters from the reconstructed growth of
convergence of the velocity of the Local Group toward the CMB dipole
motion. For scales up to 60 h ^1^ Mpc, assuming a Local Group velocity
of 627 km s^1^, we estimate {OMEGA}_m_ h ^2^ = 0.11 +/ 0.06 and
{sigma}_8_ = 0.9 +/ 0.4, in agreement with WMAP5 measurements at the
1{sigma} level. However, for scales up to 100 h ^1^ Mpc, we obtain
{OMEGA}_m_ h ^2^ = 0.08 +/ 0.03 and {sigma}_8_ = 1.0 +/ 0.4, which
agrees at the 1{sigma} to 2{sigma} level with WMAP5 results.
Key words: cosmological parameters, cosmology: observations, largescale
structure of universe, methods: data analysis, methods: numerical, methods:
statistical
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