Post on 19-Jan-2016
description
Kate Land
The Axis of Evil: revisited
astro-ph/0611518, 0502237, 0507289
27/03/07 The Axis of Evil Revisited. Kate Land
THE ISSUESAXIS OF EVIL• Planarity• Alignments• Low-power• Ecliptic issues
OTHER• Asymmetries• Cold spot
27/03/07 The Axis of Evil Revisited. Kate Land
PLANARITY & AOE“Intriguingly, both the quadrupole and the octopole are seen to have power suppressed along a particular spatial axis, which lines up between the two, roughly towards (l, b) ~ (-110, 60) in Virgo.”Tegmark & al.PRD(68)123523
27/03/07 The Axis of Evil Revisited. Kate Land
A posteriori planarity
Quadrupole
l = 2
m = 2 m = 0
27/03/07 The Axis of Evil Revisited. Kate Land
A posteriori planarity
Octopole
l = 3
m = 3 m = 1
27/03/07 The Axis of Evil Revisited. Kate Land
‘Planarity’ is quite normal -
BUT THE AXIS IS NOT!
27/03/07 The Axis of Evil Revisited. Kate Land
Independent of Gaussianity
Hard to test
Axis of Evil
27/03/07 The Axis of Evil Revisited. Kate Land
Maximum Likelihood• Avoid instabilities• Allow model comparison (Bayesian V Freq)
Multipoles share axis, and ratio
27/03/07 The Axis of Evil Revisited. Kate Land
ModelsNull
‘Planarity’ l = 2, 3 m = lParameters:
‘m-preference’ l = 2 - 5 m freeParameters:
27/03/07 The Axis of Evil Revisited. Kate Land
Maximum Likelihood
27/03/07 The Axis of Evil Revisited. Kate Land
SignificanceCompare to simulations
Information criteria‘planarity’ AIC ~ 2, BIC ~ 2.8
‘m-pref’ AIC ~ 2.8, BIC ~ 0Jeffreys’ scale > 2.5 ‘strong’
27/03/07 The Axis of Evil Revisited. Kate Land
Bayesian evidence
27/03/07 The Axis of Evil Revisited. Kate Land
What can we conclude?• Evidence for AOE depends on model and
method!
• Similarly for ns<1 (Liddle astro-ph/0701113)
• Important consequences• Combined with other anomalies• SYSTEMATICS Satellite, data pipeline, …• ASTROPHYSICAL EFFECT Foregrounds,
local lensing, …• COSMOLOGICAL FEATURE Non-FLRW
models, non-trivial topology, …
27/03/07 The Axis of Evil Revisited. Kate Land
The Axis of Evil II - SummaryCorrelations seen for l = 2,3,4,5
But how do we test the significance?Propose a model
Frequentist Bayesian
m-preference
Planarity
27/03/07 The Axis of Evil Revisited. Kate Land
Priors
27/03/07 The Axis of Evil Revisited. Kate Land
Max asym axis (57,10) Ecliptic pole (96,30) SG pole (47,6)
Cold spot (209,-57)
Axis of Evil ~(260,60) Dipole (264,48) Virgo ~(260,70)
27/03/07 The Axis of Evil Revisited. Kate Land
Information criteria
27/03/07 The Axis of Evil Revisited. Kate Land
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