1. X-RAY GROUPS WITH CHANDRA AND XMM: MASS, ENTROPY AND AGN HEATING
FABIO GASTALDELLO
UC IRVINE & BOLOGNA
D. BUOTE UCI
P. HUMPHREY UCI
L. ZAPPACOSTA UCI & TRIESTE
J. BULLOCK UCI
W. MATHEWS UCSC
F. BRIGHENTI UCSC & BOLOGNA
S. ETTORI BOLOGNA

2. OUTLINE / MOTIVATION
MASS PROFILES FOR A SAMPLE OF X-RAY BRIGHT AND RELAXED GROUPS
ENTROPY PROFILES FOR THE SAME SAMPLE. RELEVANT SCALE FOR BREAKDOWN OF SELF-SIMILARITY
AGN FEEDBACK IN AN INTERESTING OBJECTS
PRELIMINARY RESULTS ON A FLUX-LIMITED SAMPLE
Introduction with NFW and cosmological relevance of the c-M relation with current observational results
Lack of results in the group mass range which spurred the work I’m presenting here.
Method of analysis (bkg subtraction, potential approach to HE equation, care to addressing systematics)
Group results
Cosmological implications of the extended sample ranging from ellipticals to massive clusters (Buote et al. 2006)

3. Clusters X-ray results
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 = -0.040.03, P05).
Vikhlinin et al. 2006
Pointecouteau et al. 2005

4. THE PROJECT
Improve significantly the constraints on mass profiles and 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 were very few constraints on groups scale (1013 ≤ M ≤ 1014 Msun)
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

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

7. 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

8. c-M relation for groups
The values of concentration and mass obtained by the best fit NFW+stars model are plotted here. The best fitting power law obtained with the BCES estimator is plotted in red along with the B01 model for sigma_8 = 0.9.
It is this mass range which provides crucial evidence that c decreases with M
The intrinsic scatter is low, 0.030.02 which agrees with CDM only if these halos are very relaxed, reinforcing the selection for HE equilibrium
We obtain a slope α=-0.2260.076, c decreases with M at the 3σ level

9. GAS FRACTIONS
CLUSTERS
GROUPS
GASTALDELLO ET AL

10. ENTROPY PROFILES

11. ENTROPY PROFILES

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

13. COMPARISON WITH MASSIVE CLUSTERS AND GRAVITATIONAL SIMULATIONS

14. AGN FEEDBACK IN GROUPS
“UNFORTUNATELY, AGN HEATING IS NOT AS WELL STUDIED IN GROUPS AS IN CLUSTERS” (McNAMARA & NULSEN, ARAA).
NGC 5044 IS BRIGHT AND NEARBY (z=0.009). IDEAL TARGET TO STUDY AGN FEEDBACK.

15. NGC 5044 AGAIN …

16. NGC 5044 AGAIN …

17. NGC 5044 AGAIN …
CAON ET AL

18. DUST IN NGC 5044
TEMI, BRIGHENTI & MATHEWS 2007

19. 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:
10h20m-14h region due to superior re-analysis
fx > 3x10-12 erg cm-2 s-1, completeness to better than 82%
Lx < 5x1043 erg s-1
15 objects, 5 in the archive, 10 observed with a Chandra LP (400ks, PI Buote)

20. NOGS (NORAS GROUP SAMPLE)

21. NOGS (NORAS GROUP SAMPLE)

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

23. NOGS (NORAS GROUP SAMPLE)
RGH 80

24. SUMMARY
DETAILED MASS PROFILES FOR A SAMPLE OF X-RAY BRIGHT GROUPS ARE WELL FITTED BY NFW+STARS. GAS FRACTIONS ARE LOWER AND WITH MORE SCATTER COMPARED TO CLUSTERS.
BROKEN POWER LAW BEHAVIOR OF ENTROPY PROFILES POINTS TO MORE IMPORTANT LOCAL MODIFICATIONS (AGN).
IT’S TIME TO STUDY AGN FEEDBACK IN GROUPS WITH MULTI-LAMBDA DATA. NGC 5044 CAN BE THE PERSEUS OF GROUPS.
RESULTS FOR A COMPLETE X-RAY SELECTED, FLUX LIMITED SAMPLE COMING SOON. IT’S IMPORTANT TO HAVE ALSO XMM DATA TO GO TO LARGE RADII.