CLUSTERS OF GALAXIES IGM, and Scaling Laws

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

Status of The IGM Age of Clusters ~ few Gyr; R ~ 1-2 Mpc T ~ 1-10 keV; Gas highly ionized; density cm -3 Electrons free mean path Gas may be treated as a fluid Timescale for Coulomb Collisions Electrons are in kinetic equilibrium Maxwellian velocity distribution Timescale for soundwave propagation Gas is in hydrostatic equilibrium

Intracluster 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 Clusters of Galaxies in the X-ray 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 Clusters of Galaxies in the X-ray Band Beside IGM contains some metals (0.3 Solar) They produce line emission

X-ray Observations Gas densityGas density Gas TemperatureGas Temperature Gas chemical compositionGas chemical composition If assume hydrostatic equilibriumIf assume hydrostatic equilibrium Cluster Mass

Clusters –Cosmology connection Clusters are useful cosmological tools

Rosati, Borgani & Norman 03 Evolution of N(M,z) to constrain cosmological parameters

Instead of M we can either use L X  n gas 2  (T) Volume or T gas But: matter is dark & we need light to see/count/measure galaxy clusters…

Cluster Gas Density

Observables Relations L-M X-ray Luminosity

Observables Relations T-M Virial Equilibrium Kinetic Energy for the gas Thermodynamic T-M relation

X-ray scaling laws: M  T 3/2 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: M 500 = 2.22e15 (T/10 keV) 3/2 h Msun law  -model

X-ray scaling laws: M  T 3/2 Nevalainen et al. (2000) using a ASCA (clusters: 6) & ROSAT (groups: 3) T profiles: (i) in the 1-10 keV range, M 1000  T 1.8 [preheating due to SN?], but (ii) at T>4 keV, M 1000  T 3/2 [they claim, but measure 1.8  0.5 at 90%…] & norm 50% [!!!] lower than EMN : EMN96

X-ray scaling laws: M  T 3/2 Finoguenov et al. (2001) use a flux-limited sample of 63 RASS clusters (T mainly from ASCA) & 39 systems btw 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 n gas ] & z_formation (iii) M from  -model:  depends on T EMN96

X-ray scaling laws: M  T 3/2 Allen et al. (2001): 7 massive clusters observed with Chandra, M T 2500 relation. ME01 slope of 1.52  0.36 & normalization lower than 40%.

Observables Relations L-T Theoretically However from an observation point of view

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 ] T5T5 T3T3

X-ray scaling laws: evolution

Luminosity 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 & cosmological constraints Henry 00Markevitch 98

Cosmology 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,  b h 2,  m h 2.

Cosmology 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 era In non-flat cosmologies, there is degeneracy in  m -   space (e.g.   =0 is consistent with MAP results, but requires H 0 =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 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 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 Galaxies in the Microwaves Sunyaev & Zel'dovich Effect CMB+CLUSTERS

Sunyaev & Zel'dovich Effect