Thermal and non-thermal emission from galaxy clusters: X-ray and LOFAR observations

Thermal and non-thermal Thermal and non-thermal

emission from galaxy clusters: emission from galaxy clusters:

X-ray and LOFAR observationsX-ray and LOFAR observations

Chiara FerrariChiara FerrariObservatoire de la Côte d’Azur, Nice,

FRANCE

Hamburg, 18 September 2008 LOFAR Wokshop 2/44

Outline of the talk

Diffuse radio emission in clusters

Radio/X-ray comparison Importance for the study of radio halos & relics

Open questions

Study of non-thermal emission with LOFAR

Conclusions


Diffuse radio emission in clusters

A2163: VLA observations

Feretti et al. 2001, 2004

S(ν)ν-α

α 1

Relativistic electrons: γ>>1000

Magnetic fields: ~ 0.1 – 1 μGauss


X-ray images + radio contours

Feretti, Fusco-Femiano et al. 2001

A2163: XMM + VLA

Ferrari, Arnaud et al. 2006

A521: Chandra + VLA

Radio relics:extended (~1 Mpc) radio sourcescluster outskirtselongated morphology + polarised

Gitti, Ferrari et al. 2007

RX J1347-11: XMM + VLA

Radio mini halos: smaller sources ( 500

kpc) at the centre of clusters

with: AGN cooling-core

Radio halos:extended ( 1 Mpc) radio sourcesat the cluster centreregular morphology (~X-ray)


Origin of relativistic electrons

vScmcm )(,90

20

Dimensions: ~1 Mpc

Crossing time e-: ~9.5 Gyr Life time of e-: ~0.1 Gyr

A2163: radio halo

Feretti et al. 2001

30 arcmin

z ~ 0.2


Origin of relativistic electrons

Primary models: (re-)acceleration due to shocks/turbulence

(e.g. Enßlin et al. 1998; Brunetti et al. 2001, 2004;

Cassano & Brunetti 2005)

Secondary models: hadronic collisions of relativistic p+ with the ICM (e.g. Dennison 1980; Blasi & Colafrancesco 1999; Dolag &

Enßlin 2000)

Prim. + Sec. models: a combination of the two (e.g. Pfrommer et al. 2008; Cassano et al. 2008)

credits: C. Pfrommer


Measure of intracluster magnetic fields Discrepant results

Equipartition assumption: ~ 0.1 – 1 μGauss

Compton scattering of CMB photons: ~ 0.1 – 0.3 μGauss

Faraday rotation measure: ~ 1 - 10 μGauss

X-ray analysis of cold fronts: ~ 10 μGauss


Radio / X-ray comparisonNature of the non-thermal cluster component (1)

Radio + Thermal X-ray Radio + Non-Thermal X-ray



Radio + Thermal X-ray

Radio X-ray morphologies

A2163: Feretti et al. 2001

XMM (image) + VLA (contours)

A2255: Govoni et al. 2001




Halos & Relics Cluster mergers


A2256: Clarke & Enßlin 2006

Chandra (image) + VLA (contours)





P1.4GHz LX (TX )


Brunetti et al. 2007





P1.4GHz LX (TX )


Radio spectral index Distance from the X-ray centroid

A665: Feretti et al. 2004





P1.4GHz LX (TX )



Radio spectral index TX

A773: Orrù et al. 2007

3

27 M

Hz

1400

MH

Z

TX (keV)


Giant radio halos & relics: cluster mergers

Johnston-Hollitt et al. 2002

Relics ICM shocks

Giant halos turbulece

A3667

X-ray + radio contours

Govoni et al. 2004

A773

TICM + radio contours





P1.4GHz LX (TX )



Radio spectral index TX

Mini-halos AGN + cooling-core

A773: Orrù et al. 2007

3

27 M

Hz

1400

MH

Z

TX (keV)

RX J1347: Gitti, Ferrari et al. 2007

XMM (image) + VLA (contours)

TX

X-ray surf. bright.

Radio surf. bright.

Radius



Magnetic field mesurements

Rotation Measure

Cold front analysis


6 cm 3.6 cm

A 2255: Govoni et al. 2001

ROSAT (image) + VLA (contours)



Magnetic field mesurements

Rotation Measure

Cold front analysis


A 3667: Vikhlinin et al. 2001

Chandra

Magnetic layer


Chandra (red/yellow) + VLA (blue & contours)

Clarke & Ensslin 2006

Relativistic electrons: γ>>1000 CMB photons

Inverse Compton emission(hard X-ray & domain)

Radio / X-ray comparison Nature of the non-thermal cluster component (3)

Radio + Non-thermal X-ray

e- energy

distribution

synchrotron

emissivity

IC flux

S IC S radio 1 z 2 B

N N 02 1 d

J N 0 B sin 1

HXR excess

Fusco-Femiano et al. 2000

Beppo-SAX

A 2256


Main limits of current analyses Low statistics

60 clusters with detected diffuse radio emission

< 15 clusters with detected hard X-ray excess

< 10 clusters with detailed radio spectral index maps

Lack of current intruments’ sensitivity

Distribution on the Lradio vs. LX plane: bimodal or not?

Radio relics: associated to ICM shocks?

Low significance of the hard X-ray excess ( < 5)

• Systematic errors in the background level

• Lack of spatial information & ICMmulti-temperature plasma

• Contamination by AGNs


Origin of relativistic particles

Primary models ( halos & relics new tracers of large-scale structure

formation) Secondary models Primary + Secondary (Pfrommer et al. 2008: unified model for all halos

and relics)

Intra-cluster magnetic fields

Intensity & Structure

Non-thermal cluster component

Effects on the thermal ICM (energy budget, heat conduction,

overall pressure) Detection of the non-thermal HXR emission

e.g. Fusco-Femiano et al. 1999, 2004, 2007 (Beppo-SAX),

Repaheli et al. 1999, 2002 (RXTE), Eckert et al. 2008

(INTEGRAL), ...

e.g. Rossetti & Molendi 2004 (Beppo-SAX), Eckert et al. 2007

(INTEGRAL), Ota et al. 2008 (Suzaku), Ajello et al. 2008

(Swift/BAT), ...

Radio / X-ray comparison : some open

questions


Study of non-thermal emission with LOFAR:multi-wavelength comparison

Statistical studies of diffuse radio emission vs. global

cluster porperties (mass, dynamical state, LX, ...) & z

(based on « All Sky Survey » – Röttgering et al. 2008)

Detailed radio/X-ray comparisons for a cluster sub-sample Thermal X-ray emission: Chandra & XMM Non-thermal X-ray emission: Simbol-X

(based on «Deep Survey» – Röttgering et al. 2008)

coll.: Ferrari, Arnaud, Feretti, Tagger, Aghanim, ... & «Clusters of galaxies» working group

in the « Extragalactic Survey » Key Project


Diffuse radio sources with LOFAR

lo gL 1 . 4 G H z

5 10 2 4 4.18 lo gR h

500 h 7 01 k pc

0.26

Brunetti et al. 2007

Cassano et al. 2007

Bri

gh

tness p

rofi

le

1023 W/Hz 1024 W/Hz

1025 W/Hz 1026 W/Hz

Ferrari 2008

L1.4GHz =1


Statistical studiesDiffuse radio emission vs. global cluster properties & z

All Sky Survey sensitivity limits – Röttgering et al. 2008

= 1

Rhalo as a function of P1.4GHz

80% of flux detected at 10 sig. level

LX

z

Ferrari 2008




= 1



= 1.5



LX

z

Ferrari 2008




= 1



= 1

Rhalo = 0.5 Mpc


LX

z

Ferrari 2008




= 1



= 1

Rhalo = 0.5 Mpc


LX

z

Ferrari 2008




= 1



= 1

Rhalo = 0.5 Mpc


LX

z

Ferrari 2008




= 1



= 1.5



LX

z

Ferrari 2008



= 1.0 (e.g. Orrù et al. 2007)


80% of flux detected at 20 s.l. All Sky Survey (Röttgering et al. 2008)

Radio luminosity of diffuse radio sources vs.

Physical properties of their host systems (dyn. state, mass, LX, TX)

Redshift (possible connections with the Planck cluster catalogue)

Ferrari 2008



= 1.0 (e.g. Orrù et al. 2007)



Radio luminosity of diffuse radio sources vs.

Physical properties of their host systems (dyn. state, mass, LX, TX)

Redshift (possible connections with the Planck cluster catalogue)

= 1.0 (e.g. Orrù et al. 2007)



= 1.5 (e.g. Brentjens 2008)



Ferrari 2008


30 MHz

Resolution ~ 20 arcsec

20 detection - 80% of the radio flux

Ferrari 2008

Adapted from Cassano et al.

2006

Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008


30 MHz



Ferrari 2008

z = 0.1


2006



30 MHz



Ferrari 2008

z = 0.2


2006



30 MHz



Ferrari 2008

z = 0.3


2006



30 MHz



Ferrari 2008

z = 0.4


2006



30 MHz



Ferrari 2008

z = 0.5


2006



30 MHz



Ferrari 2008

z = 0.6


2006



30 MHz



Ferrari 2008

z = 0.8


2006



30 MHz



Ferrari 2008

z = 1.0


2006



Detailed radio/X-ray comparisons


2006

LOFAR estimates: Ferrari 2008

z=0.2

z=0.1

Ferrari 2008LX

z

30 MHz


20 detection

80% of the radio flux




2006


z=0.2

z=0.1

Ferrari 2008LX

z

30 MHz


20 detection


Simbol-X

Spectro-Imager

0.5-80 keV

~15“ angular resolution

~12‘ F.o.V.




2006


z=0.2

z=0.1

Ferrari 2008LX

z

30 MHz


20 detection


Brunetti et al. 2007b

# c

luste

rs w

ith

dete

cte

d

HX

R

F 60-100 keV = 10-13 erg cm-2 s-1

5 x10-12 erg cm-2 s-1

10-12 erg cm-2 s-1

B=0.2 G

B=0.2 G

B=2.0 G

Simbol-X limits




2006


@ z 0.2 !!!

z=0.2

z=0.1

Ferrari 2008LX

z

30 MHz


20 detection


Arnaud 2008

A2163 (z~0.2) + Simbol-X

F.o.V

S IC S radio 1 z 2 B

br T 1 2 e h k T n e2

Optimal for the detection of radio

relics


Conclusions

Galaxy clusters hierarchical scenario of structure formation

Physics of formation and evolution of galaxy clusters

Nature and origin of the non-thermal cluster component Statistical studies : halos/relics presence & luminosity vs.

global clusters properties (e.g. mass, dyn.

state) & z Detailed studies : radio emission in galaxy clusters

vs. thermal and non-thermal X-ray emission

+ Complementary studies

Statistical studies : e.g. possible comparison with Planck cluster catalogue

Detailed studies : e.g. energetics of the ICM & AGN feedback

Thermal and non-thermal emission from galaxy clusters: X-ray and LOFAR observations

Documents

nonthermal cluster component

radio nonthermal xraye

talkdiffuse radio emission

halos relics cluster

detected hard xray excess

galaxy clusters

xmm vlaferrari

cte dazur