Transcript Slide 1
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 SELFSIMILARITY 3. PRELIMINARY RESULTS ON A FLUX-LIMITED SAMPLE DM DENSITY PROFILE The concentration parameter c do not depend strongly on the innermost data points, r < 0.05 rvir (Bullock et al. 2001, B01; Dolag et al. 2004, D04). rvir calculated using Bryan & Norman 98 for concordance model Navarro et al. 2004 c-M RELATION •c slowly declines as M increases (slope of -0.1) •Constant scatter (σlogc ≈ 0.14) •the normalization depends sensitively on the cosmological parameters, in particular σ8 and w (D04,Kuhlen et al. 2005). Bullock et al. 2001 A SPECIAL ERA IN X-RAY ASTRONOMY Chandra •1 arcsec resolution XMM-Newton •High sensitivity due to high effective area, i.e. more photons Clusters X-ray results Pointecouteau et al. 2005 Vikhlinin et al. 2006 • 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 = -0.040.03, P05). 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 1012 ≤ M ≤ 1014 Msun •There are very few constraints on groups scale (1013 ≤ M ≤ 1014 Msun) , where numerical predictions are more accurate because a large number of halo can be simulated. SELECTION OF THE SAMPLE In Gastaldello et al. 2007 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. 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 Buote et al. 2002 NGC 5044 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 0.570.21, in reasonable agreement with SP synthesis models (≈ 1) c-M relation for groups We obtain a slope α=-0.2260.076, c decreases with M at the 3σ level THE X-RAY c-M RELATION • Buote et al. 2007 c-M relation for 39 systems ranging in mass from ellipticals to the most massive galaxy clusters (0.0620) x 1014 Msun. • 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 ENTROPY PROFILES 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 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. 2005 Gas cools AGN stops being fed AGN feedback Gas heated AWM4 AND AGN FEEDBACK 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,400d2) • 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. fx > 3x10-12 erg cm-2 s-1, completeness to better than 82% 3. Lx < 5x1043 erg s-1 • 15 objects, 5 in the archive, 10 observed with a Chandra LP (400ks, PI Buote) NOGS (NORAS GROUP SAMPLE) NOGS (NORAS GROUP SAMPLE) A 1142 A 1275 A 1185 A 1377 NOGS (NORAS GROUP SAMPLE) NGC 4104 A 1314 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 XRAY 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)