Probing the Dark Universe with Galaxy Clusters

Günther Hasinger Max-Planck Institut für extraterrestrische Physik, Garching Technische Universität München With major inputs from H. Böhringer and P. Schücker TR33-Symposium: The Dark Universe Heidelberg, 8.November 2006

Does it Matter?

After the discovery of „Antimatter“ and „Dark Matter“, we have recently discovered the existence of „Doesn‘t Matter“, which seems to have absolutely no effect on the Universe!

Formation of Large Scale Structure

Simulation of Dark Matter

Klypin, Kravtsov, Gottlöber, 1999

Clusters of Galaxies

… form at the 3D intersections of the Cosmic Web filaments Dark Matter Hot Baryons

The Role of Galaxy Clusters in the Hierarchy of Large Scale Structure

Gaussian fluctuation field 1. Cosmology determines the growth of the matter density fluctuation amplitude (with time or z) of which the cluster mark the peaks and provide a sensitive statistical measure.

2. The number counts are observed as a function of z, which also includes the volumina of dz shells – which are cosmology dependent Mass of Galaxy Clusters ~ 10 14 – 10 15 M sun

X-ray Gas in Galaxy Clusters

Hydro-Simulations

V. Springel et al., 2003, MPA

Sunyaev Zeldovich Effect Compton scattering of CMB Photons on Electrons of the hot Cluster gas.

Carlstrom et al. Sunyaev & Zeldovich, 1980, Ann. Rev. Astr. Astrophy., 18, pp.537

Simulation of SZ-Surveys

Caveats: SZ-Surveys are just about to begin. Not a single cluster has been discovered using SZ so far. Sensitivity limited by CMB fluctuation confusion. Large ground-based dishes necessary for angular resolution.

Bertoldi 2003, priv. comm.

1.

2.

Future SZ-Experiments

SZ-Cluster survey with APEX at ESO-ALMA site.

> 2500 clusters in 250 deg 2 (@ 1.4 and 2 mm) bolometer array (Start next year !) Expected cluster counts in the 4000 deg 2 SZ survey with the South Pole Telescope [Ruhl et al. astro-ph/0411122]

APEX built by MPIfR & Co



to determine

w

to about ~5% and time variation of

w

(better than 10%) when combined to about > 10-20%

Clusters of Galaxies as X-ray Sources Potential wells of Dark Matter are filled with hot gas.

Merger of two clusters in the system Abell 3528, observed with ROSAT: X-ray emission in false colours, optical galaxies in black (Schindler 2002)

Complementarity between X-rays, SZ and lensing!

Cosmos Survey

2 deg 2

Subaru Suprimcam PI: G. Hasinger

6x X-ray Clusters for Precision Cosmology 1. Cluster mass function mainly depends on the matter density W

m

and the amplitude of the primordial power spectrum s

8

2. Evolution of mass function

N(z)

3. Cluster Power Spectrum amplitude and shape depend on DM and DE 4. Baryonic Wiggles due to acoustic oscillations at recombination give tight constraints on space curvature 5. Cluster baryon fraction as a function of redshift provides constraints on DM and DE 6. Clusters provide direct distance measurements due to combined X-ray and SZ-measurements

Test I: Cluster Mass Function

Vikhlinin et al., 2005

Cluster Mass Function

Growth of cluster masses is one important effect to constrain dark energy and dark matter.

Mass of the Perseus Cluster

Assume hydrostatic equilibrium. Use gas particles as „test masses“

74-83% dark matter 15-20% hot gas 2-6% galaxies Böhringer et al., 1994 Fabian et al. 2002

Mass-Luminosity Relation

Cluster Mass Function f(z)



There are more distant clusters for small -w !

But results are very sensitive to the mass scale

Test II: Cluster LSS Distribution

ROSAT

The X-ray Sky

M. Freyberg, 1998

Combined REFLEX & NORAS Survey

Extragal. ALL-SKY RASS Survey

REFLEX 2 + NORAS 2 ~

1500

clusters F> 1.8 /2. 10 -12 erg s -1 cm -2

L X REFLEX 2: 6 runs ESO 3.6m NORAS 10runs C.A. 2 runs K.P.

Published:

REFLEX = 447 (SOUTH) (F > 3 10 -12 erg s -1 cm -2 ) NORAS 1 = 378 + 141 , incompl.;(eBCS = 299 )

redshift

Optical Identification of Clusters

Tedious optical spectroscopy on many cluster members necessary

3D distribution of ROSAT clusters

Spatial Distribution characterized by P(K)

Volume-limited samples with boxlength of: 300, 400, 500 h -1 Mpc Schuecker et al. 2001

Concordance of LSS measurements

Bias factor taken into account in a self — consistent fashion!

Tegmark & Schuecker (2002)

Constraints on Cosmological Models and

W m

from

REFLEX

Cluster Survey

ROSAT [Schuecker et al. 2002a,b] CFHTLS lensing [Hoekstra et al., 2006] WMAP 3 CMB [Spergel et al., 2006] (curves are 1,2,3 σ)  W

m ~ 0.34 +-0.05 (+ syst. errors +-0.05) 2

s

!

Comparison of Observational Constraints W L W

m

WMAP 1 results from Spergel et al. 2003 REFLEX results from Schuecker et al. 2003 (three weeks before WMAP 1 publication)

Combined Constraints REFLEX & SN Ia on

W m

and W

x

Data from REFLEX and SN observations of Riess et al. 1998 and Perlmutter et al. 1999

L  

x

(

z

) ;

w



[Schuecker et al. 2003]

L

model

P x



x

REFLEX SN Ia Riess et al. 98

W

m = 0.31 (+0.05,-0.04) W x = -1.00 (+0.20,-0.25)

Test III: Cluster Evolution

The Influence of

w

on Cosmic Evolution

Density fluctuation growth:

L w=-0.6

w=-0.2

open Def.

:

w



P X



X

N(z)

Dark Energy Equation of State: N(z)

p =

w(z)

 Based on 10000 clusters (DUO)

Prospects of cluster surveys to various depth

REFLEX2 (x100) „UCS“

eROSITA „DUO“

100K X-ray survey DUET X-ray SPT SZE Majumdar and Mohr, 2003 Haiman et al, 2005

Test V: Power Spectrum Shape & Baryonic Wiggles

P(k) and Baryonic Wiggles

Cluster Survey

Constraints from Baryon Oscillations

≥ 100 000 clusters in survey required ! Schücker 2005, priv. comm.

D k A /k A = 1.5% z=1 D k A /k A = 3.6% Baryon oscillations in cluster P(k) M>1.1x10

14 M o N=1.5x10

5 k M>1.8x10

14 M o N=4.5x10

4 k Angulo etal 05 Courtesy C. Frenk

BAO 3D correlation function

Springel et al., 2006

Self-Calibration

• N(z): Cluster mass scale is very uncertain • But cluster power spectrum P(k) amplitude also depends on mass scale • Baryonic wiggle features provide additional lever arm • Folding everything in to a Fisher matrix analysis, leaving mass scale as a free parameter, gives very tight constraints on DE (Majumdar & Mohr 2004) • Dedicated X-ray follow-up of ~1000 clusters provides temperatures and masses to calibrate scaling relations and as input for SZ-effect

Constraints from 100K Cluster Survey

Time dependence of w x w x(z) = w 0 + w a * z p(z) = w x (z) *

(

z

) Results from the White Paper submitted to the NASA/DOE Dark Energy Task Force: Haiman, … , G.H. et al., 2005, astro-ph/0507013

100K X-ray Cluster Survey

Instrumental Solution: eROSITA

The eROSITA Survey

Main goal: Study of Dark Matter and Dark Energy using the Cluster abundance, the large scale structure, the baryonic acoustic oscillations and the cosmic evolution of clusters of galaxies with a sample of ~100 000 clusters

The new Spectrum-X-Gamma Mission Lobster ART-XC eROSITA • Mission is approved on the Russian side. Launch planned on Soyus/Fregat from Baikonur in 2011. • eROSITA funding secured, DLR project start planned for 1/2007 • Additional MPG funding for mirror and detector development

New pn-CCD Chip Technology MPG is operating a dedicated semiconductor lab for the development of novel detectors optimised for high energy radiation.

Larger chips 384 x 384 pixels development The new pn-CCD detectors are significantly better, than those successfully operated aboard XMM Newton since more than 6 years (energy resolution, CTI, speed).

70 working CCDs are already available. Larger chips currently being developed !

ROSITA Wafer in HLL on Cold Chuck Probe Station

eROSITA

– 7 Mirror Systems •  35 cm (ABRIXAS 16 cm) • 54 gold-coated nickel-shells • PSF < 20 arcsec (goal 15 arcsec) • A eff ~ 2400 cm 2 • Grasp  700 cm 2 (1 keV, on-axis) deg 2 at 1 keV – 7 individual cameras • 256 × 256 pixel, 75µm • 41 × 41 arcmin 2 FoV • framestore area

ABRIXAS eROSITA

Scheme

Telescope

KT-Model MPE-Model WE-Model

Effective area and Grasp

Effective area [cm 2 ] Grasp [cm 2 deg 2 ]

ART-XC ART-XC Grasp of 7 eROSITA telescopes is 3-4 x higher than 3 XMM Newton telescopes in the energy range 0.3-2 keV!

At energies 5-15 keV, the Russian ART-XC is taking over significantly.

eROSITA Surveys

• 30000 deg 2 Cluster survey • Galactic Plane Survey 3 yrs 1 yr • 2 x 200 deg 2 Deep Survey 0.5 yr • Re-observation of high-z clusters and other interesting targets 1 yr +?

Survey-Geometry

gal. plane gal. plane ≤ 30° Ecliptic ≤ 30°

4 Year Survey, Survey Pole and “Wobble” optimised for extragalactic sky

Schematic Exposure Map

4 Years Survey optimised on extragalactic sky (30000 deg 2 ) significant survey of Galactic Plane (10000 deg 2 ) exposure rises towards the poles effectively ½ yr exposure in the poles of the survey (2 x 200 deg 2 )

The XMM-Newton COSMOS Survey A „representative“ patch of the eROSITA deep survey (Hasinger et al. 2006)

0.5-2 keV

Sensitivity

2-10 keV

We expect ~ 100,000 clusters, 3.4 Mio AGN (0.5-2 keV), ~200 QSOs at z>6 and 250000 AGN (2-10 keV). In addition > 100000 stars

Cluster Surveys

1/2y

eROSITA

4y

• • • • • • • • • Optical/X-ray/SZ follow-up

Accurate redshifts (dz ~ 0.02) to z < 1.5 for >100,000 clusters from multi-band photometry, covering wavelength of <1

m

for clusters at z=1.5, deep enough to obtain ~10 cluster members.

The Sloan Digital Sky Survey (SDSS) provides spectroscopic redshifts of cluster galaxies to z~ 0.6 over ~7000 deg 2 . PanSTARRS will survey 30,000 deg 2 survey 5000 deg 2 (g, r, i, z, Y) to z~1.5, the DES will in the South (g, r, i, z) to z≥1.3. The Large Synoptic Survey Telescope (LSST) will provide five band data for a solid angle ~20,000 deg 2 . Dedicated spectroscopic follow-up with 30 moveable IFUs possible The South Pole Telescope (SPT) will deliver a sample of more than 20,000 SZ clusters over 4000 deg 2 extending to z>1.5. The CMB mapping experiment Planck will deliver SZ observations of many massive and nearby galaxy clusters.

X-ray follow-up observations with ROSITA will provide temperatures for ~1000 clusters Interesting AGN (high-z & EXOs) and high-z clusters need 8m follow-up

Clusters and Groups in the COSMOS-Field Photo-z selected galaxy groups (colours) on XMM-Newton Wavelet extended sources Weak-lensing mass map with X-ray clusters superposed Finoguenov et al. 2006 Massey al., 2006

Virtual Observatory Cluster Identification Example: ROSAT / Sloan DSS Schuecker et al.,2004

Summary

• Clusters of galaxies provide a very good probe of Dark Matter and Dark Energy • X-ray surveys are an efficient means to find clusters of galaxies • Optical follow-up requires photometry of very large fields in preparation (e.g. PanSTARRS, DES) • Technology is ready, mission scope very moderate • Significant synergies and complementarity with surveys in other wavebands (JDEM, SZ, PanSTARRS, LSST) • Potential for new physics (e.g. clustering of DE) • Important to calibrate cluster mass scaling relations (e.g. detailed X-ray pointings & lensing!) • Spectroscopic follow-up possible but demanding Thank you very much!