Studying clusters and cosmology with Chandra

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Studying clusters and cosmology with Chandra

Some thoughts
Licia Verde Princeton University
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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

• Optical
• Redshift velocity dispersion
• Photometry and lensing

Galaxy Cluster

• mm-Wave
• SZ Compton Scattering

Cosmic Microwave Background
chandra

• X-ray Flux
• Temperature and luminosity probe mass

HOT Electrons
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SZ Signature
Hot electron gas imposes a unique spectral
signature
145 GHz decrement
220 GHz null
270 GHz increment
1.4x 1.4
Easy to find!
NO SZ Contribution in Central Band
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Clusters as Cosmological Probes

• Multiple uses
• Standard candles
• Standard rulers
• Probes of volume
• Probes of velocity field
• Probes of initial conditions

• 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

• Amplitude of fluctuations
• Scaling relations
• Gravitational lensing of CMB gives F
• Kinetic SZ gives v2
• Cluster counts give
• N(M,z)
• N(FSZ,z)

Need to know cluster physics
Linked theoretical/observational effort
essential for using these observables as
cosmological probes.
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Clusters scaling relations
(e.g., size temperature, mass-temperature)
(Verde et al. 2000)
Mohr et al 1997, Mohr et al 2000
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New scaling relations that include the SZ
decrement
(Verde, Haiman, Spergel 2002)
chandra
Observables SZ, angular size,
redshift,Temperature
constraints M-T relation
THSC
Virial relation
Total SZ decrement
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If our understanding of cluster physics is
correct
Narrow
Clusters should occupy a fundamental plane
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Modifications in the Position, orientation and
redshift evolution of the plane
Different cluster physics and/or
cosmology
Scaling relations with SZ
(THSC prediction)
narrow
broad
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Formation redshift?
Mathiessen 2001 finds no evidence for zf being
relevant to clusters properties
Only formation redshift
Only stochastic
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300 clusters with follow up
Assume cosmology, study cluster physics ?
fM Lacey Cole 94 parameter for the formation
redshift distribution
2D KS test
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Back to
Observations e.g., Xu et al. 2001, Mohr, Evrard
1997, Mohr et al 1999
Effect of formation redshift
Can constrain a fiducial model
Deviations from virialization parameterized by
For a fiducial model
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Assume cluster physics, study cosmology
Assume formation redshift distribution is
important Constraints from
Used KS, Lokelihood is much more sensitive
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MAP 2 yr
Cluster abundance
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ADD information about dN/dz (mass function)
With Z. Haiman
Break the cluster physics/cosmology degeneracy
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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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Dark energy ?
Verde et al 2002
deBernardis et al. 2001
Perlmutter et al. 1998
From Verde et al. 2002
Nature? Equation of state?
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s
MAP will constrain
and cosmological parameters
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The growth of structure (i.e. cluster abundance
evolution)
Nature of dark energy
Haiman et al. 2000
(once we know clusters physics)
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Conclusions

• X-ray CMB optical theory
• Clusters scaling relations with SZ (Tx)
• (study cluster physics and cosmology)
• constrain dark energy exploiting
• growth rate of structure

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END