CLUSTERS OF GALAXIESCLUSTERS OF GALAXIES

IGM, and Scaling LawsIGM, and Scaling Laws

Emission Processes of Emission Processes of Clusters of Galaxies in the X-Clusters of Galaxies in the X-

ray Bandray Band

Status of The IGMStatus of The IGMAge of Clusters ~ few Gyr; R ~ 1-2 MpcAge of Clusters ~ few Gyr; R ~ 1-2 MpcT T ~ 1-10 keV; Gas highly ionized; density 10~ 1-10 keV; Gas highly ionized; density 10-3-3cmcm-3-3

Electrons free mean path

Gas may be treated as a fluid

Timescale for Coulomb Collisions

Electrons are in kinetic equilibriumMaxwellian velocity distribution

Timescale for soundwave propagation

Gas is in hydrostatic equilibrium

Intracluster MediumIntracluster Medium

Hydrostatic equilibrium (spherical symmetry)

We can measure the Cluster mass

Dynamical Properties of the Galaxies

Isothermal Cluster King profile Beta Profile

Emission Processes of Emission Processes of Clusters of Galaxies in the X-Clusters of Galaxies in the X-ray Bandray Band

•The IGM is a PlasmaThe IGM is a Plasma•Electrons are accelerated by the ionsElectrons are accelerated by the ions•They emit for BremsstrahlungThey emit for Bremsstrahlung

•Electrons are in kinetic equilibrium (Maxwellian V distr. )•Cluster emission is mainly thermal Bremsstrahlung

Emission Processes of Emission Processes of Clusters of Galaxies in the X-Clusters of Galaxies in the X-ray Bandray Band

Beside IGM contains some metals (0.3 Solar)

They produce line emission

X-ray ObservationsX-ray Observations

•Gas densityGas density•Gas TemperatureGas Temperature•Gas chemical compositionGas chemical composition

•If assume hydrostatic If assume hydrostatic equilibriumequilibriumCluster MassCluster Mass

Clusters –Cosmology Clusters –Cosmology connectionconnection

Clusters are useful cosmological toolsClusters are useful cosmological tools

Rosati, Borgani & Norman 03

Evolution of N(M,z) to constrain cosmological parameters

Instead of M we can either use LX ngas

2 (T) Volumeor

Tgas

But: matter is dark & we need light to But: matter is dark & we need light to see/count/measure galaxy clusters…see/count/measure galaxy clusters…

Cluster Gas DensityCluster Gas Density

Observables RelationsObservables RelationsL-ML-M

X-ray Luminosity

Observables RelationsObservables RelationsT-MT-M

Virial Equilibrium

Kinetic Energy for the gas

Thermodynamic

T-M relation

X-ray scaling laws: X-ray scaling laws: M M T T3/23/2

Evrard, Metzler & Navarro (1996) use gasdynamic simulations to assess the accuracy of X-ray mass estimations & conclude that within an overdensity between 500 and 2500, the masses from -model are good. The scatter can be reduced if M is estimated from the tight M-T relation observed in simulations:

M500 = 2.22e15 (T/10 keV)3/2 h50-1 Msun

law

-model

X-ray scaling laws: X-ray scaling laws: M M T T3/23/2

Nevalainen et al. (2000) using a ASCA (clusters: 6) & ROSAT (groups: 3) T profiles: (i) in the 1-10 keV range, M1000 T

1.8 [preheating due to SN?], but (ii) at T>4 keV, M1000 T

3/2 [they claim, but measure 1.80.5 at 90%…] & norm 50% [!!!] lower than EMN :

EMN96

X-ray scaling laws: X-ray scaling laws: M M T T3/23/2

Finoguenov et al. (2001) use a flux-limited sample of 63 RASS clusters (T mainly from ASCA) & 39 systems btw 0.7-10 keV with ASCA T profile.

(i) Steeper profile than 3/2, high scatter in groups(ii) deviations from simulations due to pre-heating [makes flat ngas] & z_formation(iii) M from -model: depends on T

EMN96

X-ray scaling laws: X-ray scaling laws: M M T T3/23/2

Allen et al. (2001): 7 massive clusters observed with Chandra, M2500-T2500 relation.

ME01slope of 1.52 0.36 & normalization lower than 40%.

Observables RelationsObservables RelationsL-TL-T

Theoretically

However from an observation point of view

X-ray scaling laws: self-similar?X-ray scaling laws: self-similar?

We have a consistent picture at T>3 keV, but also evidence that cool clusters/groups may be not just a scaled version of high-T clusters [review in Mulchaey 2000]

T5

T3

X-ray scaling laws: evolutionX-ray scaling laws: evolution

Luminosity FunctionLuminosity Function

Local (left) & high-z (right) XLF: no evolution evident below 3e44 erg/s, but present at 3 level above it (i.e. more massive systems are rare at z>0.5) Rosati et al. 03

Temperature Function & Temperature Function & cosmological constraintscosmological constraints

Henry 00Markevitch 98

Cosmology in the WMAP eraCosmology in the WMAP era

1-st year results of the temperature anisotropies in the CMB from MAP (Bennett et al., Spergel et al 03) put alone constraints on tot, bh2, mh2.

Cosmology in the WMAP eraCosmology in the WMAP era

However, the final answer to the cosmology quest is not given:• the cosmological parameters in CMB are degenerate… complementary• the equation of state of Dark Energy & its evolution with redshift is not known• given that, we can play the reverse game: fix the cosmology & see what your cosmology-dependent data require

Cosmology in the WMAP eraCosmology in the WMAP eraIn non-flat cosmologies, there is degeneracy in m- space (e.g. =0 is consistent with MAP results, but requires H0=32 and tot=1.28…).To get tighter & non-degenerated constraints, one needs to add something else, like, P(k) from 2dF & Lyman- forest, Hubble KP, SN Ia, clusters survey…: complementarity

Allen etal 02

Cosmology in the WMAP eraCosmology in the WMAP era

The equation of state of the Dark Energy & its evolution with time: only post-MAP CMB surveys (i.e. Planck in 2007), SN Ia, X-ray/SZ clusters can answer in the next future

Cosmology in the WMAP eraCosmology in the WMAP era

The equation of state of the Dark Energy & its evolution with time: only post-MAP CMB surveys (i.e. Planck in 2007), SN Ia, X-ray/SZ clusters can answer in the next future

Mohr et al.

Clusters of GalaxiesClusters of Galaxiesin the Microwaves in the Microwaves

Sunyaev & Zel'dovich EffectCMB+CLUSTERS

Sunyaev & Zel'dovich Sunyaev & Zel'dovich EffectEffect

Sunyaev & Zel'dovich Sunyaev & Zel'dovich EffectEffect