Cosmology with theCosmology with theXMM Cluster Survey (XCS)XMM Cluster Survey (XCS)
Martin SahlMartin Sahlén, én, University of SussexUniversity of Sussex
withwithPedro Viana (Porto), Andrew Liddle, Kathy Romer (PI)Pedro Viana (Porto), Andrew Liddle, Kathy Romer (PI)
and others (XCS Consortium)and others (XCS Consortium)
COSMO ’07, University of Sussex, 22 August 2007COSMO ’07, University of Sussex, 22 August 2007
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
OutlineOutline Why Galaxy Clusters?Why Galaxy Clusters?
From Theory to Predictions:From Theory to Predictions:Simulation and ObservationSimulation and Observation
The XMM Cluster SurveyThe XMM Cluster Survey
ForecastsForecasts
Status and ConclusionsStatus and Conclusions
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Why Galaxy Clusters?Why Galaxy Clusters?
Galaxy clusters: largest grav. bound Galaxy clusters: largest grav. bound objects, hot intracluster gas – objects, hot intracluster gas – bremsstrahlung (X-ray)bremsstrahlung (X-ray)
Cluster abundance exponentially sensitive Cluster abundance exponentially sensitive to to σσ88 and and ΩΩMM → good constraining power → good constraining power
Probe structure formation; constraints Probe structure formation; constraints complementary to CMB, SNIa, etc.complementary to CMB, SNIa, etc.
Knop et al. 2003 Allen et al. 2004
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Why Galaxy Clusters Again? Why Galaxy Clusters Again?
0.22 0.25 0.28 0.31 0.34
0.75 0.8 0.85 0.9 0.95 1
8
m
8
0.22 0.25 0.28 0.31 0.340.75
0.8
0.850.9
0.95
1
None Linear No NoSelf-similar None No No
Self-similar Linear Yes NoNone None Yes No
L-T evolution L-T & M-T scatterData Fit Data Fit
Self-similar None Yes NoNone Linear Yes No
F iducial
Fiducial
Fiducial
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Theoretical ComponentsTheoretical Components
n(M, z) – comoving number density of clustersn(M, z) – comoving number density of clusters M(O, z) – relation between halo mass and direct M(O, z) – relation between halo mass and direct
observableobservable dV/dz – cosmic volume evolutiondV/dz – cosmic volume evolution ffselsel(O,z) – probability of detecting a given cluster (O,z) – probability of detecting a given cluster Uncertainties in observables and relationsUncertainties in observables and relations
dMzMfdz
dVzMnO
dz
dNsel
zM
)),((),()();(
lim
limmin
Dynamics of Cluster ScienceDynamics of Cluster Science
IC’s
Particle physics
Gravita-tional theory
Cosmo-dynamics
Cluster dynamics
Mass function Jenkins et al. 2001
BiasSheth & Tormen 1999
Mass-observable relationsMuanwong et al. 2006
Halo conc.Neto et al. 2007
THEORY SIMULATIONS FITTING FORMULAE
OBSERVATIONS
e.g. XCS
e.g. Virgo Hubble Volume
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Mass FunctionMass Function
PPδδ(k) - PS of density contrast; depends on primordial (k) - PS of density contrast; depends on primordial PS, transfer function and perturbation growth PS, transfer function and perturbation growth suppression factorsuppression factor
Primordial spectrum specified, transfer function and Primordial spectrum specified, transfer function and growth factor determined by cosmologygrowth factor determined by cosmology
Here: parameterisation for Here: parameterisation for σσ(R); (R); Viana & Liddle 1996
0
22 )()()(k
dkkPkRWR
dMdM
zMd
zMM
zFdMzMn m ),(
),(
)()(),(
8.31 61.0lnexp315.0)( JF
)(
18 Mpc8)(
R
h
RR
Jenkins mass function; Jenkins mass function; Jenkins et al. 2001
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Mass-Observable/Scaling Mass-Observable/Scaling RelationsRelations
Luminosity-TemperatureLuminosity-Temperature
Mass-TemperatureMass-Temperature
Evolution (Evolution (γγ, , δδ, , ηη, , νν)) Self-similar Self-similar γγ = 1/2, = 1/2, ηη = 1/3 = 1/3
Scatter (Scatter (σσlogLlogL, , σσlogTlogT))
Self-calibration and follow-upSelf-calibration and follow-up
)1(*)(*)(
)()(*),(),(
2
2
zzEz
zEzzTLzTL
vir
vir
),0()1()()(log),(log log223/2
1010 Tvirvir NzzzEhAMzMT
e.g. Levine et al. 2002, Lima & Hu 2004, 2005, Majumdar & Mohr 2004
),0(log*),(log log1010 LNTzTL
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
XMM Cluster Survey (XCS)XMM Cluster Survey (XCS)
Mining XMM-Newton imagesMining XMM-Newton images X-ray temperature, flux, redshiftX-ray temperature, flux, redshift
2 keV < T < 8 keV, z2 keV < T < 8 keV, zmaxmax = 1.45 = 1.45
500 500 □□˚̊ Important ‘pathfinder’ Important ‘pathfinder’
survey for e.g. SPT,survey for e.g. SPT,
E-ROSITA, and DESE-ROSITA, and DES
(XCS collaboration)(XCS collaboration) http://xcs-home.orghttp://xcs-home.org
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Selection FunctionSelection Function
Calculated using cluster detection pipeline Calculated using cluster detection pipeline with mock clusters - numerically very with mock clusters - numerically very intensive to compute (months)intensive to compute (months)
Dependencies include:Dependencies include: Halo modelHalo model X-ray spectrumX-ray spectrum Detector characteristicsDetector characteristics CosmologyCosmology
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Mock cluster added to image
Detecting Mock ClustersDetecting Mock Clusters
Original XMM-Newton image Original source detectionMock source detection
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
From Theory to PredictionsFrom Theory to Predictions N-body/hydrodynamic simulations - full non-linear N-body/hydrodynamic simulations - full non-linear
treatment, necessary!treatment, necessary!
Mass function, mass-observable relations, etc. Mass function, mass-observable relations, etc. calibrated to simulations/observationscalibrated to simulations/observations
Selection function: simulations using the Selection function: simulations using the detection pipelinedetection pipeline
Used along with cosmology to make predictionsUsed along with cosmology to make predictions
ttttt
tttseltttttt
z
z
T
T
dzdTdLdMdz
dVzTLfzMnzTLMzTLMpzTn
dTdzzTnTTzzN
),,(),(,,,|,,,),(
),(),,,(2
1
2
1
2121
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Expected Number CountsExpected Number CountsFull XCS;Full XCS;ΩΩM M = 0.3= 0.3ΩΩΛΛ = 0.7 = 0.7σσ8 8 = 0.8= 0.8
Self-sim M-TSelf-sim M-T
Scatter:Scatter:σσlogL logL = 0.3= 0.3σσlogT logT = 0.1= 0.1
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
10
20
30
40
50
60
70
z
Mea
n nu
mbe
r of
clu
ster
s in
bin
,
z =
0.0
5
M-T & L-T scatter, self-similar L-TM-T & L-T scatter, constant L-T
No scatter, self-similar L-TNo scatter, constant L-T
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Expected Constraints, Full XCSExpected Constraints, Full XCSFiducialFiducial::ΩΩM M = 0.3= 0.3ΩΩΛΛ = 0.7 = 0.7σσ8 8 = 0.8= 0.8Self-similar M-TSelf-similar M-TNo scatterNo scatter
500 500 □□˚̊2 keV < T < 8 keV2 keV < T < 8 keV0.1 < z < 10.1 < z < 1Flat universeFlat universe
0.28 0.29 0.3 0.31
0.78 0.8 0.82 0.84
8
m
8
0.29 0.3 0.31
0.78
0.8
0.82
No L-T evolution
Self-similar/linear L-Tevolution
F iducial
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Systematic BiasesSystematic Biases
0.22 0.25 0.28 0.31 0.34
0.75 0.8 0.85 0.9 0.95 1
8
m
8
0.22 0.25 0.28 0.31 0.340.75
0.8
0.850.9
0.95
1
None Linear No NoSelf-similar None No No
Self-similar Linear Yes NoNone None Yes No
L-T evolution L-T & M-T scatterData Fit Data Fit
Self-similar None Yes NoNone Linear Yes No
F iducial
Fiducial
Fiducial
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
StatusStatus XCS DR1 XCS DR1
168 168 □□˚̊
Exp. ~50-250 clusters with >500 photons and T > 2 keVExp. ~50-250 clusters with >500 photons and T > 2 keV
166 candidates, 119 confirmed with redshift, BUT clusters 166 candidates, 119 confirmed with redshift, BUT clusters with T < 2 keV not excluded yetwith T < 2 keV not excluded yet
Results expected late 2008Results expected late 2008
Full XCSFull XCS 500 500 □□˚̊
Exp. ~200-700 clusters with >500 photons and T > 2 keVExp. ~200-700 clusters with >500 photons and T > 2 keV
Results expected 2010Results expected 2010
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
ConclusionsConclusions
Cluster cosmology can be modeled Cluster cosmology can be modeled using N-body/hydrodynamic using N-body/hydrodynamic simulation results tuned to simulation results tuned to observationsobservations
A comprehensive MCMC forecasting A comprehensive MCMC forecasting and data analysis code has been and data analysis code has been developeddeveloped
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
ConclusionsConclusions
XCS DR1 (2008): XCS DR1 (2008): σσ88 to 15%, to 15%, ΩΩMM to 25% to 25% (~WMAP3)(~WMAP3)
Full XCS (2010): Full XCS (2010): σσ88 and and ΩΩMM to 5% to 5%
Knowledge of L-T scatter and evolution Knowledge of L-T scatter and evolution necessary (self-calibration/follow-up)necessary (self-calibration/follow-up)
XCS is a key step for cluster surveysXCS is a key step for cluster surveys
M. Sahlén - Cosmology with the XCS M. Sahlén - Cosmology with the XCS
Ongoing WorkOngoing Work
Self-calibrationSelf-calibration
Temperature & redshift errorsTemperature & redshift errors
Future/reference surveysFuture/reference surveys