Digging for new AstroPhysics in the old CMB

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Digging for new (Astro-)Physics in the old CMB

• Niayesh Afshordi
• Institute for Theory and Computation
• Harvard College Observatory

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Outline

• 1-Tracing dark forces on large scales
• Integrated Sachs-Wolfe (ISW) effect
• 2-Tracing pressure profile in galaxy clusters
• Thermal Sunyaev-Zeldovich (SZ) effect

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Tracing Dark Forces on Large Scales

• Integrated Sachs-Wolfe (ISW) Effect
• ISW in cross-correlation
• Constraining Dark Energy with ISW
• Incompressible Dark Energy
• Conclusions I

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Integrated Sachs-Wolfe (ISW) effect

• Domination of dark energy/ spatial curvature
• decay of linear gravitational
  potential
• Important at large angles, as it traces the
  potential
• Causes a bump in CMB power spectrum at low ls

Spergel, et al. 06
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Detecting ISW in cross-correlation

• ISW induces positive CMB correlation with
  mass/galaxy overdensities, which has been
  detected by different groups

SDSS LRGs Scranton, et al. 06, Cabre et al. 06
(3.5?) Padmanabhan, et al. 05 (2.5?)
2MASS XSC Afshordi, et al. 04 (2.5?)
Boughn Crittenden 04 Nolta, et al. 04
HEAO-A1 (2.5?)
NVSS (2?)
and others
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Pitfalls in Estimating Error Covariance

• Jack-Knife Errors
• They can underestimate errors on large scales
• Small errors in off-diagonal components add up
• Monte-Carlos are good
• CGT hGTi (?CGT)2 ' hG1G2i hT1T2i
• if applied properly
• e.g. using observed correlations to estimate
  errors may lead to an overestimate of S/N and
  even a singular covariance matrix

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Cosmological Constraints of ISW detections

• Gaztanaga, et al. 05
• Why are all the points above the model
  prediction?!

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ISW effect and Dark Energy (slide borrowed
from my 2004 talk)
Spergel et al. 2003

• ISW effect
• Not the best probe of Dark Energy
• A good probe of Large Scale Physics

• ISW effect
• Not the best probe of Dark Energy
• (disclaimer depends on the DE model, 2006)
• A good probe of Large Scale Physics

SDSS 2dF
Perfect ISW, zlt 3
Afshordi 2005
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Incompressible Dark Energy
With

• Take the scalar field action
• In the field comoving frame,
• ??? 0 but ?P? ? 0 ? cs 1
• Field equation becomes a constraint equation that
  uniquely determines as a function of metric

Ghazal Geshnizjani
Daniel Chung University of Wisconsin-Madison
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FRW Cosmology with IDE (temporary name)

• Field Equation
• Friedmann equation

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More cosmology with IDE

• IDE is a minimal theory for evolving dark energy,
  as it has no internal dynamics
• Examples
• Quadratic Potential
• Evolves exactly as ?CDM
• Only differs when fluctuations cross horizon
• Exponential Potential
• Evolves exactly as DGP cosmology

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ISW in quadratic IDE

• Evolution of perturbations on sub-horizon and
  super-horizon scales only depends on H(z), and so
  is indistinguishable from ?CDM
• Perturbations decay as they enter the horizon
• Non-trivial effects on llt100 primary CMB

ISWSW, arbitrary units
?m0.1, ?IDEon0.2
?m0.3, ?IDEon0
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ISW in exponential IDE

• Fixing the distance to the last-scattering
  surface, DGP-like IDE produces a far greater ISW
  signal than standard ?CDM

ISWSW, arbitrary units
DGP-like cosmology
?m0.3, ?IDEon0
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IDE as Modified Gravity

• Since IDE has no internal dynamics, it can be
  viewed as a (non-local) modification to gravity

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Conclusions (Part I)

• ISW effect can be used to trace the evolution of
  gravitational potential
• ISW can be detected in cross-correlation, and
  constrain DE models, but beware of pitfalls in
  error estimates
• IDE is a minimal theory of evolving dark energy,
  and can be tested by its ISW signature

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Tracing the Thermal Energy of the Universe

• Thermal Sunyev-Zeldovich (SZ) effect
• Intracluster Medium (ICM) gas fraction
• Reconstructing the ICM pressure profile
• Missing ICM baryons
• The Moral

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My Collaborators

• Yen-Ting Lin
• University of Illinois Urbana-Champaign
• Princeton
• Alastair Sanderson
• University of Illinois Urbana-Champaign
• University of Birmingham
• Daisuke Nagai
• CalTech
• Afshordi, Lin, Sanderson 2005 (1st yr)
• Afshordi, Lin, Nagai, Sanderson 2006 (3 yrs)
  in preparation

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Thermal Sunyaev-Zeldovich (SZ) Effectand
Intra-Cluster Medium (ICM)

• Probes the thermal energy distribution of
  electrons in the Intra-Cluster Medium
• Dominates CMB at angles lt 0.1o
• Generates an anti-correlation between WMAP and
  galaxy/cluster distribution

WMAP sees here
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Can SZ surveys sustain the CMB dominance?

• SZ clusters can be
• Detected up to high redshifts
• Their number counts probe Dark Energy/Cosmology
• Many SZ surveys are underway APEX, SZA, ACT,
  SPT, Planck,
• Can they deliver? Calibration of SZ-Mass
  relation, Gastrophysics,

Courtesy of John Carlstrom
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In the mean time
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SZ detections in Cross-Correlationwith
Galaxy/Cluster Surveys

• Bennett et al. 2003 (XBACs clusters 2.5?)
• Fosalba, Gaztanaga, Castander 2003 Fosalba
  Gaztanaga 2004 (SDSS, APM 2.7?)
• Myers et al. 2004 (APMACO 2?)
• Afshordi, Loh, Strauss 2004 (2MASS 3.7?)

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tSZ in 2MASSxWMAP Correlation

• Afshordi, Loh, Strauss (2MASS Deepest magnitude
  bin)
• data best fit model
• ISW SZ
  Point Sources

• Cluster physics is mixed with cosmology,
• and non-linear bias ?
• Does not employ the non-Gaussianity of the
  signal ?

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How to get the most physics out?

• Most Galaxies are NOT in clusters
• Most SZ signal comes from clusters
• thus
• The SZ detection is more significant if we just
  look around clusters ? Make an SZ template
• The S/N is maximized if the template matches the
  actual SZ profile ? Constraint on the SZ profile
  

Template
Observed Sky
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WMAP SZ clusters

• Three close-by clusters in the 3yr cleaned map
  (Tegmark et al)

Abell 133
Abell 1656
Abell 2319
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Match-filter SZ detection in an X-ray cluster
catalog

• Compile a catalog of 116 low-z X-ray clusters
  with measured temperatures
• Compile the X-ray estimated gas mass for most of
  them
• ICM/ Point Source template
• NFW gravitational potential
• Hydrostatic equilibrium
• Polytropic equation of state Pgas / (?gas)?eff
  ?eff 1.2
• Point sources follow DM profile

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Gas Fraction vs. Temperature (WMAP 1yr)
Afshordi, et al. 2005

• The mean gas fraction of ICM is 20-40 less
  than cosmic budget
• ltfgas hgt 0.08 0.01(ran) 0.01(sys)
• Comparable S/N to higher resolution
  interferometers (e.g. OVRO/BIMA Grego et al.
  2001)
• X-ray gas mass estimates consistent with SZ
  estimates
• Both X-ray and SZ gas mass estimates show an
  increasing trend with Tx

• SZ observation
• X-ray Observation

fgas Mgas/Mtot , H0 100 h km/s/Mpc
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Gas Fraction vs. Temperature (WMAP 1yr)
Afshordi, et al. 2005
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New Analysis (WMAP 3 years)

• WMAP 3 years
• Temperature Q,V,W
• Nres 9 (pixel size ' 0.1 deg)
• 417 clusters
• meaured X-ray temperature

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Dangers of model-dependent analysis

• X-ray ?-model overpredicts SZ on large angles by
  a factor of 4

WMAP
Lieu, et al. 05
ROSAT ?-model fits
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Methodology

• Find R200 for each cluster using M200-TX relation
• Constrain pressure within spherical radial bins
  centered at 0.25,0.5,1,2,4,8 x R200 a central
  radio source
• Only consider pixels close to each cluster, with
  resolution degrading with distance
• ? Makes covariance matrix tractable

Degraded Abell 2319 in Q-band
Abell 2319 in Q-band
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Temperature-Weighted Gas Fraction
Q-band V-band W-band Hydro-Simulations
All Clusters
TX gt 5 keV 144 Clusters
No significant frequency dependence ? No
significant point source contamination
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Universal Pressure Profile

• __ ?CDM/?crit
• __ Hydro-Simulations
• WMAP best fit
• __ Random Realizations of WMAP best fit

TX gt 5 keV 144 Clusters
Prior ?gas gt 0
??2 ' 110 for the simulated profiles ? 10.5?
detection
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Total ICM gas fraction

• __ Hydro-Simulations
• __ Random realization of WMAP best fit
• WMAP best fit

Cosmic Concordance ?b/?M 0.18 0.01 WMAP SZ
clusters fgas 0.09 0.007 Hydro-Simulations
fgas 0.095 0.01 fgas 0.11 0.01
CHANDRA X-ray clusters
OVRO/BIMA
13? model independent measurement of SZ
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40 of Baryons are missing from the ICM!

• Where are the rest of baryons?
• stars are only 15
• Intracluster stars
• cold starless clouds
• warm gas (105-106 K)? soft X-ray excess?!
• Something wrong with simulations?
• may be Te ? Ti

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The Moral

• In the run-up to high resolution SZ surveys,
  there is much more that can and should be learnt
  about ICM
• Higher Resolution CMB/SZ surveys (Planck, SZA,
  APEX, SPT, ) will be able to significantly lower
  their effective cluster detection mass threshold
  thru combination with wide-angle X-ray cluster
  surveys (e.g., DUO)
• X-ray and SZ surveys must be combined in a model-
  independent way to provide reliable tests for
  models of Dark Energy or Cluster Physics