Wiener Reconstruction of the Galaxy Redshift Surveys

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Wiener Reconstruction of the Galaxy Redshift
Surveys

• Pirin Erdogdu, Ofer Lahav, Saleem Zaroubi and the
  2dFGRS Team

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The Reconstructed Density Field of 2dFGRS in
Declination Strips
We assign
Pirin Erdogdu and 2dFGRS Team, 2003, in
preparation
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Motivation

• Statistical Uncertainties due to Shot Noise
• Incomplete Sky Coverage
• Incomplete Galaxy Sampling
• Recovering one field from another

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Wiener Filter
(For details see Zaroubi et al 1995, ApJ, 449,
446)
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where the matrix WF is chosen such that the
residual
is minimised.
Hence
prior/(prior noise)
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Data Data Correlation Matrix
Signal Data Cross-Correlation Matrix
Density Reconstruction in Redshift Space

Density Reconstruction in Real Space
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Pixelisation
Application to 2df Survey
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EACH GALAXY IS ASSIGNED THE WEIGHT
So the data vector is written as
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2dFGRS SGP
SCGP01
VSGP02
VSGP01
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Density Threshold as A Function of Redshift
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2dFGRS NGP
VNGP26
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2dFGRS SGP
SCSGP 21
SCSGP22
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Are these structures real?
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FUTURE WORK
Large Scale Reconstruction from Peculiar
Velocities
And assuming
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Reconstruction from Mark III data.
Zaroubi, Hoffman Dekel 1999 ApJ,520, 412
Top Right panel Mark III data Top Left Panel
IRAS data
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WORK IN PROGRESS
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Conclusions

• WF is applied to the density reconstruction of
  2dFGRS
• Major superclusters and voids are identified.
• WF can be used to reconstruct the density and
  velocity fields of 6dFGRS.
• The reconstructed density fields can be used as
  an input to different analyses.