TWO SAMPLES OF X-RAY GROUPS

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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
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OUTLINE / MOTIVATION

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

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DM DENSITY PROFILE
The concentration parameter c do not depend
strongly on the innermost data points, r lt 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
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c-M RELATION

• c slowly declines as M increases (slope of -0.1)
• Constant scatter (slogc 0.14)
• the normalization depends sensitively on the
  cosmological parameters, in particular s8 and w
  (D04,Kuhlen et al. 2005).

Bullock et al. 2001
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A SPECIAL ERA IN X-RAY ASTRONOMY

• High sensitivity due to high effective area, i.e.
  more photons

• 1 arcsec resolution

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Clusters X-ray results
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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.

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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.

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RESULTS

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

MKW 4
NGC 533
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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
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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)

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c-M relation for groups
We obtain a slope a-0.226?0.076, c decreases
with M at the 3s level
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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
  (6.6s) that c decreases with increasing M
• Normalization and scatter consistent with relaxed
  objects

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THE X-RAY c-M RELATION
WMAP 1 yr Spergel et al. 2003
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THE X-RAY c-M RELATION
WMAP 3yr Spergel et al. 2006
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ENTROPY PROFILES
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ENTROPY PROFILES
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ENTROPY PROFILES
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THE BASELINE INTRACLUSTER ENTROPY PROFILE FROM
GRAVITATIONAL STRUCTURE FORMATION
VOIT ET AL. 2005
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COMPARISON WITH MASSIVE CLUSTERS AND
GRAVITATIONAL SIMULATIONS
PRATT ET AL. 2006
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COMPARISON WITH MASSIVE CLUSTERS AND
GRAVITATIONAL SIMULATIONS
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COMPARISON WITH MASSIVE CLUSTERS AND
GRAVITATIONAL SIMULATIONS
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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
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AWM4 AND AGN FEEDBACK
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AWM4 AND AGN FEEDBACK
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NOGS (NORAS GROUP SAMPLE)

• Purely X-ray selected flux limited samples have
  been very effective in cluster studies
  (e.g.,Gioia90,Edge90,Rosati95,Scharf97,Vikhlin
  in98,Romer00,Bohringer00) 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 (Henry95)
• We used the NORAS catalogue
• 10h20m-14h region due to superior re-analysis
• fx gt 3x10-12 erg cm-2 s-1, completeness to better
  than 82
• Lx lt 5x1043 erg s-1
• 15 objects, 5 in the archive, 10 observed with a
  Chandra LP (400ks, PI Buote)

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NOGS (NORAS GROUP SAMPLE)
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NOGS (NORAS GROUP SAMPLE)
A 1142
A 1185
A 1275
A 1377
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NOGS (NORAS GROUP SAMPLE)
NGC 5129
NGC 4104
A 1314
RXJ 022
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NOGS (NORAS GROUP SAMPLE)
A 1177
RGH 80
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SUMMARY

• DETAILED MASS PROFILES FOR A SAMPLE OF X-RAY
  BRIGHT GROUPS ARE WELL FITTED BY NFWSTARS. 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)