Transcript Slide 1
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 10-3cm-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 Plasma •Electrons are accelerated by the ions •They 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 density •Gas Temperature •Gas chemical composition •If assume hydrostatic equilibrium Cluster Mass Clusters –Cosmology connection Clusters are useful cosmological tools Evolution of N(M,z) to constrain cosmological parameters Rosati, Borgani & Norman 03 But: matter is dark & we need light to see/count/measure galaxy clusters… Instead of M we can either use LX ngas2 (T) Volume or Tgas 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 T3/2 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 -model law X-ray scaling laws: M T3/2 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: M T3/2 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: M T3/2 Allen et al. (2001): 7 massive clusters observed with Chandra, M2500-T2500 relation. slope of 1.52 0.36 & normalization lower than 40%. ME01 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] T3 T5 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 Markevitch 98 Henry 00 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, bh2, mh2. 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 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 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, Xray/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, Xray/SZ clusters can answer in the next future Mohr et al. Clusters of Galaxies in the Microwaves CMB+CLUSTERS Sunyaev & Zel'dovich Effect Sunyaev & Zel'dovich Effect Sunyaev & Zel'dovich Effect