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Studying clusters and cosmology

with Chandra

Licia VerdeLicia Verde Princeton University

Some thoughts…

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Overview

•The potential of combining: X-rays + optical + CMB…..

•Clusters scaling relations with X-rays and the Sunyaev-Zeldovich effect

• constraining dark energy (Quintessence) •Conclusions

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Coordinated Cluster Measurements

X-ray Flux: • Temperature and luminosity probe

mass

mm-Wave: • SZ – Compton Scattering

Optical: • Redshift velocity dispersion• Photometry and lensing

Galaxy Cluster

HOT Electrons chandra

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SZ SignatureHot electron gas imposes a unique spectral signature

NO SZ Contribution in Central Band

145 GHzdecrement

220 GHznull

270 GHzincrement

1.4°x 1.4°Easy to find!

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Multiple uses• Standard candles

• Standard rulers

• Probes of volume

• Probes of velocity field

• Probes of initial conditions

Clusters as Cosmological Probes

Multiple observables

• Clusters counts (*)

• SZ luminosity

• Central SZ decrement

• X-ray temperature (*)

• X-ray luminosity(*)

• Angular size(*)

• Velocity Dispersion

• Redshift

• Lensing Mass

• Kinetic SZ amplitude

Linked theoretical/observational effort essential for using these observables as cosmological probes.

• Amplitude of fluctuations

• Scaling relations

• Gravitational lensing of CMB gives

• Kinetic SZ gives v2

• Cluster counts give– N(M,z)

– N(FSZ,z)

Need to know cluster physics

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Clusters scaling relationsClusters scaling relations

Mohr et al 1997, Mohr et al 2000

(e.g., size temperature, mass-temperature)

(Verde et al. 2000)

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New scaling relations that include the SZ decrementNew scaling relations that include the SZ decrement

Observables: SZ, angular size, redshift,Temperature

“constraints”: M-T relation /1)1( MzT f

)1,5.1(

Virial relation MTR

Total SZ decrement22

Ad

TMS

(Verde, Haiman, Spergel 2002)chandra

THSC

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If our understanding of cluster physics is correct

Clusters should occupy a fundamental plane

Narrow

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Different cluster physics and/or cosmology

Modifications in the Position, orientation and redshift evolution of the planeScaling relations with SZ

narrow broad

(THSC prediction)

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Formation redshift?Formation redshift?

Only formation redshift Only stochastic

Mathiessen 2001 finds no evidence for zf being relevant to clusters properties

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2D KS test

fM Lacey & Cole 94 parameter for the formation redshift distribution

Assume cosmology, study cluster physics

300 clusters with follow up

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/1)1( MzT fBack to: )1,5.1(

Observations e.g., Xu et al. 2001, Mohr, Evrard 1997, Mohr et al 1999

98.16.1

Effect of formation redshift 6.1eff

Deviations from virialization parameterized by

Can constrain a fiducial model:05.01.05.1

03.01For a fiducial model

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Assume formation redshift distribution is importantConstraints from zSz ,,Used KS, Lokelihood is much more sensitive

Assume cluster physics, study cosmology

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MAP 2 yr

Clusterabundance

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ADD information about dN/dz (mass function)

Break the cluster physics/cosmology degeneracy

With Z. Haiman

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Shown a “taste” of the many possibilites

The fundamental plane/scaling relations approach can be generalized to include other observables such as velocity dispersion, X-ray luminosity, shear, central SZ decrement….

Used KS test, likelihood is much more sensitive

Insensitive to the mass function and independent from it

Can be used in tandem with dN/dz (clusters counts) to lift degeneracies between cosmology and cluster physics

Important to constrain clusters physics (fixed cosmology)

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Perlmutter et al. 1998

deBernardis et al. 2001

Verde et al 2002

Nature? Equation of state?

Dark energy Dark energy

From Verde et al. 2002

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MAP will constrain and cosmological parameters

The growth of structure (i.e. cluster abundance evolution)

Nature ofdark energy

(once we know clusters physics)

Haiman et al. 2000

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• X-ray +CMB +optical + theory

• Clusters scaling relations with SZ (Tx) (study cluster physics and cosmology)

• constrain dark energy exploiting growth rate of structure

Conclusions

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END