arXiv:1109.4527

2011/10/27 Oxford
Astrophysics Seminar
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Introduction
ISW effect due to spherical voids/clusters
Late ISW effect & other CMB effects
Statistical analysis
Summary
Future prospects~3σ deviation in kurtosis using spherical mexican-hat
wavelets (Cruz et al. 2003)

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~3σ deviation in kurtosis using spherical mexican-hat
wavelets (Cruz et al. 2003)
but not significant for non-compensated filters(Smith &Huterer 2010)

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~3σ deviation in kurtosis using spherical mexican-hat
wavelets (Cruz et al. 2003)
but not significant for non-compensated filters(Smith &Huterer 2010)~3σ deviation for signals smoothed by a top-hat
compensating filter (Inoue, Sakai & Tomita 2010)Areas are the same.

SScompensating top-hat-filter
cuncompensating top-hat-filter

Inoue, Sakai & Tomita 2010

Smoothing scale

σILC map

Q+V+W mapInoue, Sakai & Tomita 2010

Smoothing scale Sample number~observed area/size of filtering At=5 degree , significance is 0.7-1 %(~2σ)
at =12 degree, significance is 0.01-0.2%(~3σ)

Optimal filter for a cold spot surrounded by a hot ring?

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A supervoid with r~200Mpc/h, δ~-0.3 at z~1(Inoue & Silk 2006)
A hot ring cannot be produced by a compensating void
( Tomita & Inoue 2007 Inoue & Sakai 2008 )A texture at z~5 (Cruz et al. 2007)
Statistical fluke?

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A dip of 20-45% in the surface brightness in radio bands(Rudnick, Brown, & Williams 2007)

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No significant dip in galaxy counts at 0.3<z<1 in thel.o.s to the center of the CS ( Bremer et al. 2010,Granett et al. 2010)

A low-density region at z~0.2 in 2MASS galaxy catalog
may contribute 8μK to the CS (Francis & Peacock 2010)

z～0

Shapley
concentrationz~1(Inoue & Silk, 2006&2007)“the Cold Spot”

(Inoue & Silk2007)

2MASSLocal ISW
0.0<z<0.1

0.1<z<0.2

0.2<z<0.3(Francis &Peacock, 2010)

Q1. If a void is non-compensated, cana hot ring be produced and statisticallymore probable?
A1. Yes it can. But not probable.

Q2. Even if it is a fluke, what is theexpected ISW contribution froma possible low-density region to the CS?
A2. It is about 10 %.

TheoryThin-shell approx. (Inoue & Silk 2006&2007)
2nd order perturbations (Tomita & Inoue 2008)
LTB solutions (Sakai & Inoue 2008)

Observation
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SDSS LRGs (Granett et al. 2008)
2MASS photo-z (Francis & Peacock 2009)

temperature fluctuation due to time-evolving
gravitational potential
LSS

Gravitational potential

accelerated
expansion-DEspace→low temperature for CMB photons that passthrough a void

temperature fluctuation due to time-evolving
gravitational potential
LSS

Gravitational potential

accelerated
expansion

DEspace→high temperature for CMB photons that passthrough a cluster

Gravitational potential

accelerated
expansion

+

space

peculiar
velocity

LSS

Gravitational potential

accelerated
expansion+

peculiar
velocity

DE

space

clustervoid(Tomita & Inoue 2008)

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Massive wall around a void could increase
the CMB temperature.

Less massive “void wall” around a cluster could
decrease the CMB temperature.

Quasi-linear perturbation can be estimatedusing 2nd order perturbation (Tomita & Inoue 2008)void density contrast 1z  10clusterz 1  -1
H0-1

H0-1

 0 0H0-1

H0-1

voidtemperature variation cluster L  0.1

 L  -0.1
degreez 1degree L  -0.6

 L  0.6

degreedegreeA hot ring surrounding a cold spot can beproduced by an over-compensated voideven in an accelerating epoch.
 A cold ring surrounding a hot spot canbe produced by an under-compensatedcluster even in an accelerating epoch.
 A cold ring surrounding a cold spot can beproduced by an under-compensatednon-linear cluster.
A hot ring surrounding a cold spot can beproduced by an over-compensated voideven in an accelerating epoch.
 A cold ring surrounding a hot spot canbe produced by an under-uncompensatedcluster even in an accelerating epoch.
 A cold ring surrounding a cold spot can beproduced by an under-uncompensatednon-linear cluster.
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Ordinary Sachs-Wolfe (OSW) effect: spatial fluctuation on the last scattering surface.

Doppler effect:spatial fluctuation of the fluid velocity on LSS.

Early integrated Sachs-Wolfe (ISW) effect: time evolving potential at radiation->matter epoch.

Late integrated Sachs-Wolfe (ISW) effect: time evolving potential at matter->Λ epoch.

ISW+OSWISWISW z<1.5

ISW z>1.5

2.73K ×sqrt of angular power

OSWtotal

1σ=18μKWe assume there is a spherical top-hat type void
(low density region) in the l.o.s. to the CS at z<1.5.

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We assume a concordant cosmology with(  0.74, m  0.26, b  0.044, 8  0.80, h  0.72, n  0.96)
We assume that the CS is produced by a late ISW
due to a void at z<1.5 (low density region) plus
the OSW, earlyISW, and Doppler effects. No correlation
with the fluctuations at the LSS is assumed.

σΔTf(1σ)=18μK

ε=1
θin=12oΔTf(1σ)
=18μK

ε=0σo

θin=12

ΔTf(1σ)
=18μK
σ

ε=-1
θin=12oEven in an accelerated epoch, a hot ringsurrounding a cold spot can be produced if a voidis locally over-compensated but it is less probable.

Assuming that a single moderately
undercompensated low density region in thedirection to the CS at z<1.5, the expected
contribution to the CMB is about 10 % and theradius is about 600 h -1 Mpc and ~ -0.009 at z~1.
The probability of chance alignment is 0.7%. 100%
LSS is 7 times less probable.

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Deviation from perfect spherical symmetry may
be important as the assumed underdense region
is in linear regime.

Other underdense regions in the l.o.s.may bealso important especially if spatial correlation isimportant (void-in-void) (Tomita & Inoue `11 inpreparation).
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If a low density region at z~1 does not exist, we needto consider more anomalous fluctuationsat z<1 or z>1.

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Photo-z or spectroscopic survey aiming at z<1.5 witha wide-range field (>100 degree^2) to the CS isimportant.

About 10 % decrease in TE correlation in the l.o.s to
the CS is expected (observable by Planck?)