THE X-RAY C-M RELATIONTHE X-RAY C-M RELATION

FABIO GASTALDELLOINAF-IASF MILANO, UCI

D. BUOTE, S. ETTORI, P. HUMPHREY, L. ZAPPACOSTA, A. LECCARDI, S. MOLENDI, M. ROSSETTI, J. BULLOCK, M.

MENEGHETTI, W. MATHEWS, F. BRIGHENTI

OUTLINEOUTLINE

1. INTRODUCTION: c-M AS COSMOLOGICAL TOOL 2. c-M RELATION FOR THE LOCAL SAMPLE3. c-M FOR THE SAMPLE OF 44 CLUSTERS AT z=0.1-0.34. CONCLUSIONS

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).

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; Macciò et al. 2008,M08).

c-M RELATIONc-M RELATION

Macciò et al. 2008

X-RAY MASS DETERMINATIONX-RAY MASS DETERMINATION

• Spectra averaged within circular annuli• Normalization / shape of spectrum gives gas density

/ temperature

X-RAY MASS DETERMINATIONX-RAY MASS DETERMINATION

A) Deproject with no need to assume parametrized quantities for gas quantities but smoothing required to obtain a physical mass profile

(smoothed inversion)

B) Forward-fitting: fit gas density and temperature fit gas density and temperature simultaneously assuming only parameterizations simultaneously assuming only parameterizations

for density (or T or entropy) and massfor density (or T or entropy) and massBuote & Humphrey 11

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

MKW 4

NGC 533

STARS

GAS

DM

THE LOCAL X-RAY c-M RELATION THE LOCAL X-RAY c-M RELATION • Buote, Gastaldello 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 (slope -0.172 ± 0.026)

• Normalization and scatter consistent with relaxed objects

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

WMAP 1 yr Spergel et al. 2003

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

WMAP 3yr Spergel et al. 2006

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 SAMPLE @ z = 0.1 – 0.3THE SAMPLE @ z = 0.1 – 0.3• In Ettori, Gastaldello et al. (2010) we used the sample from Leccardi & Molendi (2008), all hot clusters (kT > 3.3 keV) in the range 0.1 < z < 0.3, with detailed temperature profiles secured by performing accurate background modelling•Even though clusters showing evidence of recent and strong interactions were excluded, we have not only regular and relaxed clusters in the sample. They are characterized by the entropy ratios, following Leccardi et al. (2010), which are closely related to the dynamical disturbance

A 2204 LEC A 1763 HEC

c-M @ z = 0.1 – 0.3c-M @ z = 0.1 – 0.3

c-M @ z = 0.1 – 0.3c-M @ z = 0.1 – 0.3Slope steeper than predicted by simulations, it can not be constrained in the narrow mass range (all -0.50 ± 0.07, LEC -0.28 ± 0.15). Normalization in agreement. Constraints improve when considering only clusters with rs within the data and only LEC clusters. Concentration biased high in disturbed systems (e.g., Lau et al. 2009).

COSMOLOGICAL CONSTRAINTSCOSMOLOGICAL CONSTRAINTS

OPEN ISSUESOPEN ISSUES

• HYDROSTATIC EQUILIBRIUM• SELECTION EFFECTS• RADIAL RANGE OF DATA TO OBTAIN MASS PROFILE • THEORETICAL/SIMULATION PREDICTION• ADIABATIC CONTRACTION

BIAS IN HE DERIVED cBIAS IN HE DERIVED c

Lau et al. (2009)

TURBULENT PRESSURE RISING W/ RADIUS AND MORE IMPORTANT IN DISTURBED OBJECTS. SEE RASIA ET AL., MENEGHETTI ET AL.

WHAT ARE WE REALLY SELECTING WHEN WE SELECT “RELAXED” OBJECTS ?

Wechsler et al. 2002

SELECTION EFFECTSSELECTION EFFECTS

De Boni et al. 2013

RADIAL RANGE OF DATARADIAL RANGE OF DATA

Humphrey et al. (2012)

RXJ 1159

SUMMARY & CONCLUSIONSSUMMARY & CONCLUSIONS

•c-M relation as determined from X-rays has provided independent evidence of hierarchical structure formation, in particular when fitted over a wide range of masses•c-M relation offers interesting and novel approach to potentially constrain cosmological parameters. Selection effects, HE, radial range of the data, response of DM to baryons (adiabatic contraction) and semi-analytic/ N-body simulations are open issues which have to be better characterized and improved.