TWO SAMPLES OF X-RAY TWO SAMPLES OF X-RAY GROUPS GROUPS

FABIO GASTALDELLO

UC IRVINE & BOLOGNAD. BUOTE

P. HUMPHREY

L. ZAPPACOSTA

J. BULLOCK

W. MATHEWS UCSC

F. BRIGHENTI BOLOGNA

OUTLINE / MOTIVATIONOUTLINE / 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 PROFILEDM DENSITY PROFILE

Navarro et al. 2004

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

c-M RELATIONc-M RELATION

Bullock et al. 2001

•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).

A SPECIAL ERA IN X-RAY ASTRONOMY

Chandra XMM-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 = -0.040.03, P05).

Vikhlinin et al. 2006Pointecouteau et al. 2005

Clusters X-ray resultsClusters X-ray results

THE PROJECTTHE 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.

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.

SELECTION OF THE SAMPLESELECTION OF THE SAMPLE

RESULTSRESULTS•After accounting for the mass of the hot gas, NFW + stars is the best fit model

MKW 4

NGC 533

RESULTSRESULTS•No detection of stellar mass due to poor sampling in the inner 20 kpc or localized AGN disturbance

NGC 5044

Buote et al. 2002

RESULTSRESULTS

•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 groupsc-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 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 (0.06-20) 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 THE X-RAY c-M RELATION

WMAP 1 yr Spergel et al. 2003

THE X-RAY c-M RELATION THE X-RAY c-M RELATION

WMAP 3yr Spergel et al. 2006

ENTROPY PROFILESENTROPY PROFILES

ENTROPY PROFILESENTROPY PROFILES

ENTROPY PROFILESENTROPY PROFILES

THE BASELINE INTRACLUSTER ENTROPY THE BASELINE INTRACLUSTER ENTROPY PROFILE FROM GRAVITATIONAL STRUCTURE PROFILE FROM GRAVITATIONAL STRUCTURE

FORMATIONFORMATION

VOIT ET AL. 2005

COMPARISON WITH MASSIVE CLUSTERS AND COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONSGRAVITATIONAL SIMULATIONS

PRATT ET AL. 2006

COMPARISON WITH MASSIVE CLUSTERS AND COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONSGRAVITATIONAL SIMULATIONS

COMPARISON WITH MASSIVE CLUSTERS AND COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONSGRAVITATIONAL SIMULATIONS

AWM4 AND AGN FEEDBACKAWM4 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 feedback

Gas heated

AGN stops being fed

AWM4 AND AGN FEEDBACKAWM4 AND AGN FEEDBACK

AWM4 AND AGN FEEDBACKAWM4 AND AGN FEEDBACK

NOGS (NORAS GROUP SAMPLE)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,Bohringer+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)

NOGS (NORAS GROUP SAMPLE)NOGS (NORAS GROUP SAMPLE)

A 1275

A 1142A 1185

A 1377

NOGS (NORAS GROUP SAMPLE)NOGS (NORAS GROUP SAMPLE)

A 1314

NGC 4104

NGC 5129

RXJ 022

NOGS (NORAS GROUP SAMPLE)NOGS (NORAS GROUP SAMPLE)

A 1177

RGH 80

SUMMARYSUMMARY

• 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)