Thermal and non-thermal emission from galaxy clusters: X-ray and LOFAR observations
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Transcript of 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
Hamburg, 18 September 2008 LOFAR Wokshop 3/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 4/44
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)
Hamburg, 18 September 2008 LOFAR Wokshop 5/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 6/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 7/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 8/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray Radio + Non-Thermal X-ray
Hamburg, 18 September 2008 LOFAR Wokshop 9/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Radio X-ray morphologies
A2163: Feretti et al. 2001
XMM (image) + VLA (contours)
A2255: Govoni et al. 2001
Hamburg, 18 September 2008 LOFAR Wokshop 10/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Halos & Relics Cluster mergers
Radio X-ray morphologies
A2256: Clarke & Enßlin 2006
Chandra (image) + VLA (contours)
Hamburg, 18 September 2008 LOFAR Wokshop 11/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Halos & Relics Cluster mergers
P1.4GHz LX (TX )
Radio X-ray morphologies
Brunetti et al. 2007
Hamburg, 18 September 2008 LOFAR Wokshop 12/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Halos & Relics Cluster mergers
P1.4GHz LX (TX )
Radio X-ray morphologies
Radio spectral index Distance from the X-ray centroid
A665: Feretti et al. 2004
Hamburg, 18 September 2008 LOFAR Wokshop 13/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Halos & Relics Cluster mergers
P1.4GHz LX (TX )
Radio X-ray morphologies
Radio spectral index Distance from the X-ray centroid
Radio spectral index TX
A773: Orrù et al. 2007
3
27 M
Hz
1400
MH
Z
TX (keV)
Hamburg, 18 September 2008 LOFAR Wokshop 14/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 15/44
Radio / X-ray comparisonNature of the non-thermal cluster component (1)
Radio + Thermal X-ray
Halos & Relics Cluster mergers
P1.4GHz LX (TX )
Radio X-ray morphologies
Radio spectral index Distance from the X-ray centroid
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
Hamburg, 18 September 2008 LOFAR Wokshop 16/44
Radio / X-ray comparisonNature of the non-thermal cluster component (2)
Magnetic field mesurements
Rotation Measure
Cold front analysis
Radio + Thermal X-ray
6 cm 3.6 cm
A 2255: Govoni et al. 2001
ROSAT (image) + VLA (contours)
Hamburg, 18 September 2008 LOFAR Wokshop 17/44
Radio / X-ray comparisonNature of the non-thermal cluster component (2)
Magnetic field mesurements
Rotation Measure
Cold front analysis
Radio + Thermal X-ray
A 3667: Vikhlinin et al. 2001
Chandra
Magnetic layer
Hamburg, 18 September 2008 LOFAR Wokshop 18/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 19/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 20/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 21/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 22/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 23/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 24/44
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
= 1.5
Rhalo as a function of P1.4GHz
50% of flux detected at 10 sig. level
LX
z
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 25/44
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
= 1
Rhalo = 0.5 Mpc
80% of flux detected at 10 sig. level
LX
z
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 26/44
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
= 1
Rhalo = 0.5 Mpc
50% of flux detected at 10 sig. level
LX
z
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 27/44
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
= 1
Rhalo = 0.5 Mpc
80% of flux detected at 20 sig. level
LX
z
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 28/44
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
= 1.5
Rhalo as a function of P1.4GHz
50% of flux detected at 10 sig. level
LX
z
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 29/44
Statistical studiesDiffuse radio emission vs. global cluster properties & z
= 1.0 (e.g. Orrù et al. 2007)
Rhalo as a function of P1.4GHz
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
Hamburg, 18 September 2008 LOFAR Wokshop 30/44
Statistical studiesDiffuse radio emission vs. global cluster properties & z
= 1.0 (e.g. Orrù et al. 2007)
Rhalo as a function of P1.4GHz
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)
= 1.0 (e.g. Orrù et al. 2007)
Rhalo as a function of P1.4GHz
80% of flux detected at 20 sig. level
= 1.5 (e.g. Brentjens 2008)
Rhalo as a function of P1.4GHz
80% of flux detected at 20 s.l. All Sky Survey (Röttgering et al. 2008)
Ferrari 2008
Hamburg, 18 September 2008 LOFAR Wokshop 31/44
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
Hamburg, 18 September 2008 LOFAR Wokshop 32/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.1
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 33/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.2
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 34/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.3
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 35/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.4
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 36/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.5
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 37/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.6
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 38/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 0.8
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 39/44
30 MHz
Resolution ~ 20 arcsec
20 detection - 80% of the radio flux
Ferrari 2008
z = 1.0
Adapted from Cassano et al.
2006
Detailed radio/X-ray comparisonsDeep Survey sensitivity limits – Röttgering et al. 2008
Hamburg, 18 September 2008 LOFAR Wokshop 40/44
Detailed radio/X-ray comparisons
Adapted from Cassano et al.
2006
LOFAR estimates: Ferrari 2008
z=0.2
z=0.1
Ferrari 2008LX
z
30 MHz
Resolution ~ 20 arcsec
20 detection
80% of the radio flux
Hamburg, 18 September 2008 LOFAR Wokshop 41/44
Detailed radio/X-ray comparisons
Adapted from Cassano et al.
2006
LOFAR estimates: Ferrari 2008
z=0.2
z=0.1
Ferrari 2008LX
z
30 MHz
Resolution ~ 20 arcsec
20 detection
80% of the radio flux
Simbol-X
Spectro-Imager
0.5-80 keV
~15“ angular resolution
~12‘ F.o.V.
Hamburg, 18 September 2008 LOFAR Wokshop 42/44
Detailed radio/X-ray comparisons
Adapted from Cassano et al.
2006
LOFAR estimates: Ferrari 2008
z=0.2
z=0.1
Ferrari 2008LX
z
30 MHz
Resolution ~ 20 arcsec
20 detection
80% of the radio flux
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
Hamburg, 18 September 2008 LOFAR Wokshop 43/44
Detailed radio/X-ray comparisons
Adapted from Cassano et al.
2006
LOFAR estimates: Ferrari 2008
@ z 0.2 !!!
z=0.2
z=0.1
Ferrari 2008LX
z
30 MHz
Resolution ~ 20 arcsec
20 detection
80% of the radio flux
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
Hamburg, 18 September 2008 LOFAR Wokshop 44/44
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