MASS AND ENTROPY PROFILES OF X-RAY BRIGHT RELAXED GROUPS FABIO GASTALDELLO UC IRVINE & BOLOGNA D. BUOTE P. HUMPHREY L. ZAPPACOSTA J. BULLOCK W. MATHEWS UCSC F. BRIGHENTI BOLOGNA

OUTLINE 1.MASS RESULTS AND c-M PLOT FOR X-RAY GROUPS 2.ENTROPY PROFILES 3.FOCUS ON SOME PARTICULAR OBJECTS

DM DENSITY PROFILE Navarro et al The concentration parameter c do not depend strongly on the innermost data points, r < 0.05 r vir (Bullock et al. 2001, B01; Dolag et al. 2004, D04).

c-M RELATION Bullock et al c slowly declines as M increases (slope of -0.1) Constant scatter (σ logc ≈ 0.14) the normalization depends sensitively on the cosmological parameters, in particular σ 8 and w (D04,Kuhlen et al. 2005).

Concentrations for relaxed halos are larger by 10% compared to the whole population (Jing 2000, Wechsler 2002, Maccio’ 2006). They show also smaller scatter (σ logc ≈ 0.10) Wechsler et al Selection Effects

A SPECIAL ERA IN X-RAY ASTRONOMY ChandraXMM-Newton 1 arcsec resolution High sensitivity due to high effective area, i.e. more photons

NFW a good fit to the mass profile c-M relation is consistent with no variation in c and with the gentle decline with increasing M expected from CDM ( α =  0.03, P05). Vikhlinin et al Pointecouteau et al Clusters X-ray results

THE PROJECT Improve significantly the constraints on the c-M relation by analyzing a wider mass range with many more systems, in particular obtaining accurate mass constraints on relaxed systems with ≤ M ≤ M sun There are very few constraints on groups scale (10 13 ≤ M ≤ M sun ), where numerical predictions are more accurate because a large number of halo can be simulated.

In Gastaldello et al we selected a sample of 16 objects in the 1-3 keV range from the XMM and Chandra archives with the best available data with no obvious disturbance in surface brightness at large scale with a dominant elliptical galaxy at the center with a cool core with a Fe gradient The best we can do to ensure hydrostatic equilibrium and recover mass from X-rays. SELECTION OF THE SAMPLE

RESULTS After accounting for the mass of the hot gas, NFW + stars is the best fit model MKW 4 NGC 533

RESULTS No detection of stellar mass due to poor sampling in the inner 20 kpc or localized AGN disturbance NGC 5044 Buote et al. 2002

RESULTS NFW + stars best fit model We failed to detect stellar mass in all objects, due to poor sampling in the inner 20 kpc or localized AGN disturbance. Stellar M/L in K band for the objects with best available data is 0.57  0.21, in reasonable agreement with SP synthesis models (≈ 1) Adopting more complicated models, like introducing AC or N04 did not improve the fits. AC produces too low stellar mass-to- light ratios

c-M relation for groups We obtain a slope α=  0.076, c decreases with M at the 3σ level

THE X-RAY c-M RELATION Buote et al c-M relation for 39 systems ranging in mass from ellipticals to the most massive galaxy clusters ( ) x M sun. A power law fit requires at high significance (6.6σ) that c decreases with increasing M Normalization and scatter consistent with relaxed objects

THE X-RAY c-M RELATION WMAP 1 yr Spergel et al. 2003

THE X-RAY c-M RELATION WMAP 3yr Spergel et al. 2006

CLUSTERS PREFER HIGH σ 8 Evrard et al. 2007

CLUSTERS PREFER HIGH σ 8 Evrard et al. 2007

CAVEATS/FUTURE WORK HE (10-15% from simulations, e.g. Nagai et al. 2006, Rasia et al. 2006). No results yet on the magnitude for the bias on c (if there is one) due to radial dependence of turbulence Selection bias Semi-analytic model prediction of c-M Gas physics and AC (problems also with rotation curves of spirals: Kassim et al. 2006, Gnedin et al but also positive claims: M31 mass model of Seigar et al. 2007) Extend the profiles at large radii (r 500 is possible to reach for groups)

MASS CONCLUSIONS The crucial mass regime of groups has provided the crucial evidence of the decrease of c with increasing M c-M relation offers interesting and novel approach to potentially constrain cosmological parameters See constraints on the c-z relation (poster by L. Zappacosta)

ENTROPY PROFILES

THE BASELINE INTRACLUSTER ENTROPY PROFILE FROM GRAVITATIONAL STRUCTURE FORMATION VOIT ET AL. 2005

COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONS PRATT ET AL. 2006

COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONS

ENTROPY PROFILES FOR AGN HEATING VOIT ET AL. 2006

ENTROPY PROFILES NGC 4325 AGN DISTURBANCE: RUSSELL ET AL. 2007

ENTROPY PROFILES

RGH80

AWM4 AND AGN FEEDBACK “In this scenario there is a clear dichotomy between active and radio quiet clusters: one would expect the cluster population to bifurcate into systems with strong temperature gradients and feedback and those without either” Donahue et al. 2005

AWM4 AND AGN FEEDBACK

ENTROPY CONCLUSIONS BROKEN POWER LAW ENTROPY PROFILES FOR GROUPS WITH STEEPER INNER SLOPES AND FLATTER OUTER SLOPES SEEM TO POINT TO HIGHER IMPORTANCE OF LOCAL AGN HEATING INTERPLAY BETWEEN AGN AND MERGINGS THE PUZZLE AWM4 (MORE DATA: RADIO, POSTER BY S. GIACINTUCCI, CHANDRA !)