Cosmology with baryon wiggles

1
Cosmology with baryon wiggles
Sarah Bridle, UCL, London

• What are baryon wiggles?
• Recent detections
• Detection of wiggles with photozs
• Uncertainties on w
• The Square Kilometer Array (SKA)

2
UCLs new cosmology sub-group

• Faculty
• Ofer Lahav (Head of Astrophysics Group of 80)
• Sarah Bridle
• Jochen Weller
• Post-doctoral
• Filipe Abdalla
• Eduardo Cypriano
• Currently advertising 2 positions
• PhD students
• Chris Lintott (3rd year)
• Alexandra Abate (2nd year)
• Anais Rassat (2nd year)
• Keith Biner (1st year)
• Jiayu Tang (1st year)
• Angeliki Kitiakou (1st year)
• Currently advertising more

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UCL
Imperial
Queen Mary
4
Concordance Model
70 Dark Energy
5 Baryonic Matter
25 Cold Dark Matter
5
Probes of Dark Energy
Cosmic Shear
Evolution of dark matter perturbations
Angular diameter distance
Growth rate of structure
Baryon Wiggles
Standard ruler
Angular diameter distance
Supernovae
Standard candle
Luminosity distance
Cluster counts
Evolution of dark matter perturbations
Angular diameter distance
Growth rate of structure
CMB
Snapshot at 400,000 yr, viewed from z0
Angular diameter distance to z1000
Growth rate of structure (from ISW)
6
Surveys to measure Dark Energy
2015
2005
2010
Imaging
CFHTLS
LSST
SKA
SUBARU
DUNE
DES, VISTA
Hypersuprime
ATLAS
KIDS
JDEM
SDSS
DLS
Pan-STARRS
Spectroscopy
SKA
FMOS
WFMOS
LAMOST
ATLAS
SDSS
Supernovae
DES
LSST
CSP
ESSENCE
Pan-STARRS
JDEM/ SNAP
CFHTLS
Clusters
AMI
APEX
SPT
DES
SZA
AMIBA
ACT
XCS
CMB
WMAP 2/3
WMAP 6 yr
Planck
2015
2005
2010
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Matter Power Spectrum
Wiggles
Wayne Hu
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Taken from Max Tegmarks web page
10
Dark energy from wiggles

• Galaxy survey measures
• angular scale of wiggles at z of galaxy survey
• gives DA(zsurvey)/sCMB
• length of wiggles along line of sight at zsurvey
• H(zsurvey)/sCMB
• sCMB sound horizon at CMB
• CMB measures
• angular scale of CMB first peak
• gives DA(zCMB)/sCMB
• DA and H(z) depend on dark energy quantity ?DE
  and equation of state wp/?

11
Recent detections of the baryonic signature

• Cole et al
• 221,414 galaxies, bJ lt 19.45
• (final 2dFGRS catalogue)
• Eisenstein et al
• 46,748 luminous red galaxies (LRGs)
• (from the Sloan Digital Sky Survey)

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The 2dFGRS power spectrum
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after dividing out smooth line
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The SDSS LRG correlation fn
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after multiplying the y axis by x2
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2dF wiggle detection
?b/?m 0.185 0.046
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SDSS wiggle detection
18
Surveys to measure Dark Energy
2015
2005
2010
Imaging
CFHTLS
LSST
SKA
SUBARU
DUNE
DES, VISTA
Hypersuprime
ATLAS
KIDS
JDEM
SDSS
DLS
Pan-STARRS
Spectroscopy
SKA
FMOS
WFMOS
LAMOST
ATLAS
SDSS
Supernovae
DES
LSST
CSP
ESSENCE
Pan-STARRS
JDEM/ SNAP
CFHTLS
Clusters
AMI
APEX
SPT
DES
SZA
AMIBA
ACT
XCS
CMB
WMAP 2/3
WMAP 6 yr
Planck
2015
2005
2010
19
Are photoz BAO surveys competitive?

• What do we lose cf specz?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

20
Are photoz BAO surveys competitive?

• What do we lose cf specz?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

21
Glazebrook Blake astro-ph/0505608
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Non-linear theory
23
Non-linear theory
Photo-zs only
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Non-linear theory
Photo-zs only
See Zhan Knox 2005 for use of red lines to
measure H/?z
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H/s
DA/s
Glazebrook Blake 2005
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Increasing photo-z accuracy
Blake Bridle astro-ph/0411713
27
Are photoz BAO surveys competitive?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

28

Photo-z with ANNz (Collister Lahav)
DES (griz) 5-yr alone
DES VISTA (YJHKs)
?z 0.13
?z0.08
z output
z output

Collister Lahav
Collister Lahav
z input
z input
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griz
DES Whitepaper astro-ph/0510346
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VISTA
griz
DES Whitepaper astro-ph/0510346
?z ?68/(1z) 0.03
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Are photoz BAO surveys competitive?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

32

• Fit a cosmological
• model with varying
• ?b
• ?b / ?m gt0?

Blake Bridle astro-ph/0411713
Same method as Percival et al and Cole et al for
2dF
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Blake Bridle astro-ph/0411713
9 ?
3.5 ?
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Blake Bridle astro-ph/0411713
35

• Fit a sin wave instead
• Model independent.
• amplitude gt0?

Blake Bridle astro-ph/0411713
Following Blake Glazebrook and Seo Eisenstein
36
Blake Bridle astro-ph/0411713
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Are photoz BAO surveys competitive?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

38
Blake Bridle astro-ph/0411713
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Can photo-z surveys fill the gap?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w
• Comparison with WFMOS

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grizVISTA
kmax for linear theory
by Chris Blake
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Priors applied
Results obtained
DESVISTA
by Chris Blake
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by Chris Blake
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Glazebrook Blake 2005
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by Chris Blake
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Constraints on w(z)
Glazebrook Blake astro-ph/0505608
See also Dolney, Jain, Takada 2005
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Predictions for LSST
Zhan, Knox, Tyson, Margoniner 2005
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Are photoz BAO surveys competitive?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• Errors on w?
• Requirements?

48
Requirements

• Homogeneous photometric calibration
• Galactic extinction
• Cirrus
• Representative spectroscopic calibration sample
• VVDS IAB lt24 50,000 zs
• DEEP2
• WFMOS?!

49
Surveys to measure Dark Energy
2015
2005
2010
Imaging
CFHTLS
LSST
SKA
SUBARU
DUNE
DES, VISTA
Hyper suprime
ATLAS
KIDS
SDSS
DLS
JDEM
Pan-STARRS
Spectroscopy
SKA
FMOS
WFMOS
LAMOST
ATLAS
SDSS
Supernovae
DES
LSST
CSP
ESSENCE
Pan-STARRS
JDEM/ SNAP
CFHTLS
Clusters
AMI
APEX
SPT
DES
SZA
AMIBA
ACT
XCS
CMB
WMAP 2/3
WMAP 6 yr
Planck
Planck 4yr
2015
2005
2010
50
Surveys to measure Dark Energy
2015
2005
2010
Imaging
CFHTLS
LSST
SKA
SUBARU
DUNE
DES, VISTA
Hyper suprime
ATLAS
KIDS
JDEM
SDSS
DLS
Pan-STARRS
SKA
FMOS
WFMOS
Wiggles
LSST
DES, VISTA
LAMOST
Hyper suprime
ATLAS
SDSS
JDEM
Pan-STARRS
Supernovae
DES
LSST
CSP
ESSENCE
Pan-STARRS
JDEM/ SNAP
CFHTLS
Clusters
AMI
APEX
SPT
DES
SZA
AMIBA
ACT
XCS
CMB
WMAP 2/3
WMAP 6 yr
Planck
Planck 4yr
2015
2005
2010
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What can the SKA do for cosmology?

• Will cosmology be solved in 10 years time?
• What cosmological tests can you do in the radio?

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The Big Questions in Cosmology

• Is the current cosmological model correct?
• How did the Universe begin?
• What is the dark matter?
• What is the dark energy?

Will these be solved in 15 years time?
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The Square Kilometer Array (SKA)

• Radio telescope, measures HI line
• The ultimate galaxy redshift survey, 108
  galaxies!
• velocity dispersions and imaging
• Many complementary ways to find w(z)
• Baryon Wiggles
• Cosmic Shear

www.skatelescope.org
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Blake, Abdalla, Bridle Rawlings SKA Science Case
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SDSS Pope et al

• omegab/omegam v omegam h

Blake, Abdalla, Bridle Rawlings SKA Science Case
SKA
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Blake, Abdalla, Bridle Rawlings SKA Science Case
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Baryon wiggles ? DA(z)/s
Blake, Abdalla, Bridle Rawlings SKA Science Case
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Blake, Abdalla, Bridle Rawlings SKA Science Case
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Cosmic Shear
Tyson et al 2002
61

• Great resolution possible

• Well known psf

Abdalla, Blake, Bridle Rawlings in prep
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Refregier, Massey, Rhodes, Ellis et al.
Error ? 1/vfsky
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Decreasing systematic errors
Decreasing random errors
64
Blake, Abdalla, Bridle Rawlings To appear in
SKA Science Case
SN and wiggles assume we know Om to ?0.01
SN assume we know Om to ?0.01
So far we only use one z bin for lensing
calculation
65
Summary

• Baryon wiggles can tell us about the dark energy
• The baryonic signature has already been
  detected
• Photo-z surveys can see the wiggles
• Need 10 times the area cf spec-z
• Photo-z galaxy surveys may take over from spec-z
  surveys for periods
• The SKA may be the ultimate spec-z galaxy survey

66
www.cosmocoffee.info
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END
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Are photoz BAO surveys competitive?

• Is any BAO information available?
• What photo-z accuracy can we expect?
• How well will this detect the wiggles?
• How much more area is reqd cf spec-z ?
• How well can the BAO scale be measured?
• Errors on w?
• Requirements?

69

• Fit a sin wave instead
• Model independent.
• amplitude gt0?
• k position ?

Blake Bridle astro-ph/0411713
Following Blake Glazebrook and Seo Eisenstein
70
Blake Bridle astro-ph/0411713
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Divide through by smooth P(k), use 2 z bins
DESVISTA
by Chris Blake
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2dFGRS
?m h2 0.121 /- 0.011
SDSS
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Method for DES ?w estimate

• Fit a sin wave to P(k)/Psmooth(k)
• Find kA of wiggles (for given assumed DA)
• Find ?kA ()
• Tests show ?kA / kA is indep of DA
• For trial cosmology, find kA, DA
• Transform observed kA and ?kA for trial DA
• Calculate ?2
• Obtain errors on w

As in Blake Glazebrook 2004
76
Method for calculating ? w(Blake Glazebrook
ApJ astro-ph/0301632)

• Generate many mock galaxy surveys
• For each, get P(k), divide smooth, fit sinusoid
• ? error bar DA/s for a given z slice
• Accuracy doesnt depend on w
• Use eqns for s(?m h2), DA(?m, w(z))
• For convenience use two big z slices
• In practice could break up further and fit
• Preliminary analysis confirms this

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Wiggles in the matter power spectrum
Taken from Wayne Hus web page
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2dFGRS
SDSS
80
4/15
81
4/15
See Zhan Knox 2005 for use of red lines to
measure H/?z
82
Increasing photo-z accuracy
Blake Bridle astro-ph/0411713
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Blake Bridle astro-ph/0411713
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Same results from sine wave fitting
Blake Bridle 2005
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Glazebrook Blake astro-ph/0505608
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Blake Bridle astro-ph/0411713
9 ?
3.5 ?
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Blake Bridle astro-ph/0411713
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What if dark energy nature evolves?

• Assumption of w(z)constant is arbitrary
• Eg. Maor et al showed degeneracy with Wm

94
What if dark energy nature evolves?

• Assumption of w(z)constant is arbitrary
• Eg. Maor et al showed degeneracy with Wm
• One option Taylor expand
• w(z) w0 w1 z w2 z2
• w(z) w0 wa z/(1z)
• How well can we measure the coefficients?

95
Fainter
Accelerating
?m 1, no DE
Decelerating
Perlmutter et al.1998
Further away
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Adapted from Maor et al 2001
Input model Wm0.3, w(z)-0.8 0.6z
97
Prospects not great

• Hard to measure w1 from even SNAP data
• Need good estimate of Wm
• Prospects for measuring w2, w3 worse
• Need a different approach?

98
The effective equation of state

• Measure DL(z)
• eg. SNAP
• Fit a constant w model ? w0
• eg. assume Wm0.3
• How is w0 related to w(z)?
• given that the true w may vary with time..

99
A weighted average?

• w0 ? w(z) ?(z) dz

Observational uncertainties on DL at each
redshift
Yes! To a very good approximation (1)
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The weighting function for SNAP
w0 ? w(z) ?(z) dz
z0.3
Saini, Padmanabhan Bridle 2003
101
The weighting function for CMB
from DA
w0 ? w(z) ?(z) dz
z1.3
Saini, Padmanabhan Bridle 2003
102
Consider a strongly evolving w(z)
wCMB -1
wSN -2.3
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Cosmic Shear
Tyson et al 2002
104
The weighting function for SNAP CS
wconst? w(z) ?(z) dz
?(z)
Simpson Bridle astro-ph/0411673
z
105
Comparison of CS and SN
wconst? w(z) ?(z) dz
Supernovae
Why the difference? Why the change in gradient?
?(z)
Simpson Bridle astro-ph/0411673
Cosmic Shear
z
Go to slide 57 for SA