Isotropy of Hubble Diagrams

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Isotropy of Hubble Diagrams

• by Bastian Weinhorst

Bielefeld, 11.05.2006
in collaboration with Dominik J. Schwarz
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Motivation

• The cosmological principle states that the
  universe is homogeneous and isotropic on large
  scales it is important to test this fundamental
  principle in every thinkable way
• The Hubble law is a direct consequence of the
  cosmological principle
• The need for Dark Energy and equivalently the
  value of q0 relies on high-z and low-z SN data,
  mostly the latter will be tested upon
  anisotropies
• Large scale pertubations give rise to
  anisotropies in the Hubble diagram
• There are anomalies on the largest angular scales
  in the CMB Are there similiar anomalies in SN
  Ia data?

(Bonvin, Durrer, Gasparini astro-ph/0511183 )
(Copi, Huterer, Schwarz, Starkmann
astro-ph/0605135 )
Strategy model independent tests (no Friedmann
equations)
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Hubble Diagram
The Hubble law to first order
Delta
z in CMB frame
Data taken from (Tonry et al. astro-ph/0305008)
redshift z
(Barris et al. astro-ph/0310843)
bin 1 2 3 4 5 6 7 8
redshift 0.0-0.0125 0.0125-0.025 0.025-0.05 0.05-0.1 0.1-0.4 0.4-0.5 0.5-0.7 0.7-2.0
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Analysing-Tools
Normally one can fit H0 by finding the minimum of
the following ?²
Additionally we added a dipole-term
Minimizing gives a set of parameters for monopole
and dipole in each bin
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Sn Ia Dipole WMAP Dipole?
(Hinshaw et al. astro-ph/0603451)
0.0000ltzhlt0.0125
0.0125ltzhlt0.025
?²min/DOF1.39
?²min/DOF0.46
0.025ltzhlt0.05
0.05ltzh lt0.1
?²min/DOF1.52
?²min/DOF1.07
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Dipole-Fits in CMB rest frame
0.1ltzlt0.4
0.1ltzlt0.4
Pointsize ?, Color ?, ?²min/DOF 1.22
?²min/DOF 1.22
0.7ltzlt2.0
0.7ltzlt2.0
Pointsize ?, Color ?, ?²min/DOF 0.68
?²min/DOF 0.68
Color dipole-amplitude
Contours C.L. for dipole-direction
Pointsize?, Color ?
Contours C.L. for dipole-direction
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Direction-dependent evidence for acceleration?
The Hubble law to second order in redshift (for
zlt0.1)
This gives
Minimizing ?² gives values for H0, q0 and
confidence intervals
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Evidence for acceleration?
Isotropy of Hubble diagrams
l0,b90, ?²min/DOF0.97
l0,b -90, ?²min/DOF0.98
Sn with redshifts 0.0ltzlt0.1
S
N
?²min/DOF0.99
?
l90,b -45, ?²min/DOF0.91
l270,b45, ?²min/DOF0.95
SE
NW
?
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Conclusions

• We confirm the direction of the CMB-dipole with
  Sn Ia data
• We find additional dipoles for 0.7ltzlt2.0 and
  0.1ltzlt0.4, which seem to be correlated to the
  unexpected quadrupole-octopole plane of the CMB
• We find hemispherical anisotropies in Hubble
  diagrams below z0.1, i.e. no evidence for
  acceleration in the northern hemisphere
• Plan to repeat hemispherical analysis within ?CDM

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Thank you for your interest and attention
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quadrupoleoctopole WMAP3yr fullsky map
(Copi, Huterer, Schwarz, Starkmann
astro-ph/0605135 )