TWO SAMPLES OF X-RAY GROUPS FABIO GASTALDELLO UC IRVINE & BOLOGNA D. BUOTE P. HUMPHREY L. ZAPPACOSTA J. BULLOCK W. MATHEWS UCSC F. BRIGHENTI BOLOGNA

OUTLINE / MOTIVATION 1.MASS PROFILES AND c-M PLOT FOR A SAMPLE OF X-RAY BRIGHT AND RELAXED GROUPS 2.ENTROPY PROFILES FOR THE SAME SAMPLE. RELEVANT SCALE FOR BREAKDOWN OF SELF- SIMILARITY 3.PRELIMINARY RESULTS ON A FLUX-LIMITED SAMPLE

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). r vir calculated using Bryan & Norman 98 for concordance model

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).

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)

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

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

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 Gas cools AGN feedback Gas heated AGN stops being fed

AWM4 AND AGN FEEDBACK

NOGS (NORAS GROUP SAMPLE) Purely X-ray selected flux limited samples have been very effective in cluster studies (e.g.,Gioia+90,Edge+90,Rosati+95,Scharf+97,Vikhlinin+98,Romer+00,Bo hringer+00) and they have follow-up studies with XMM or Chandra (REXCESS,400d 2 ) Groups have been historically selected in the optical band, only one pioneering study of 8 groups from the ROSAT NEP survey (Henry+95) We used the NORAS catalogue: 1.10h20m-14h region due to superior re-analysis 2.f x > 3x erg cm -2 s -1, completeness to better than 82% 3.L x < 5x10 43 erg s objects, 5 in the archive, 10 observed with a Chandra LP (400ks, PI Buote)

NOGS (NORAS GROUP SAMPLE)

A 1275 A 1142 A 1185 A 1377

NOGS (NORAS GROUP SAMPLE) A 1314 NGC 4104 NGC 5129 RXJ 022

NOGS (NORAS GROUP SAMPLE) A 1177 RGH 80

SUMMARY DETAILED MASS PROFILES FOR A SAMPLE OF X-RAY BRIGHT GROUPS ARE WELL FITTED BY NFW+STARS. THE X- RAY c-M RELATION POINTS TO A COMPROMISE WMAP COSMOLOGY (EVRARD ET AL. 07, YEPES TALK) BROKEN POWER LAW BEHAVIOR OF ENTROPY PROFILES POINTS TO MORE IMPORTANT LOCAL MODIFICATIONS (AGN) STAY TUNED FOR RESULTS FOR A COMPLETE X-RAY SELECTED, FLUX LIMITED SAMPLE (AND MORE FUN TO COME WITH XMM-LSS AND COSMOS)