Unveiling the composition of plasma bubbles with the SZ-effect “The SZ Effect and ALMA” Institut d’Astrophysique Spatiale, Orsay (France)
Christoph Pfrommer (MPA) [email protected]
Unveiling the composition of plasma bubbles with the SZ-effect – p.1/15 Plasma bubbles (1)
Perseus cluster Abell 2052 (NASA/IoA/A.Fabian et al.) (Blanton et al., 2001)
Unveiling the composition of plasma bubbles with the SZ-effect – p.2/15 Plasma bubbles (2)
Hydra A cluster MS 0735 cluster (X-ray: NASA/CXC/SAO; Radio: NRAO) (X-ray: NASA/CXC/Ohio U./ B.McNamara et al.; Radio: NRAO/VLA)
Unveiling the composition of plasma bubbles with the SZ-effect – p.3/15 Why caring about plasma bubbles?
• minimum energy arguments show: εCRe 0.1εth where is the ‘missing’ pressure? ' → radio plasma bubbles ghost cavity transition: • ↔ 1. is there an influence on the dynamically dominant component? 2. inferring the magnetic field configuration, cross field diffusivity composition of AGN jets: hadronic leptonic scenario • ↔ • plasma bubble - cool core connection: cooling core cluster experienced only moderate accretion over the last Gyr (no major merger), cooling gas ‘triggered’ AGN activity detailed physical understanding of governing processes → This work: C.P., Torsten Enßlin, & Craig Sarazin, 2005, A&A, 430, 799
Unveiling the composition of plasma bubbles with the SZ-effect – p.4/15 Idea Disadvantages of bubble X-ray observations: L n2√kT X ∝ e e
• hot dilute gas does barely contribute to X-ray luminosity • projected foreground and background emission contaminates weak signal
• projected substructure in outer regions could mock signal Advantages of bubble SZ observations:
• SZ effect measures directly the ‘missing’ quantity pressure
• possibility of bubble detections in outer cluster regions
Unveiling the composition of plasma bubbles with the SZ-effect – p.5/15 SZ effect (1) Planckian distribution function of the CMB I(x):
2(kT )3 x3 I(x) = i i(x) = CMB , 0 (hc)2 ex 1 − The relative change δi(x) in flux density as a function of dimensionless frequency x = hν/(kTCMB) for a line-of-sight through a galaxy cluster is given by
δi(x) = g(x) y h(x) w + [j(x) i(x)] τ gas − gas − rel thermal SZ effect relativistic SZ effect kinetic SZ effect
Unveiling the composition of plasma bubbles with the SZ-effect – p.6/15 SZ effect (2)
• Amplitude of the thermal SZ effect: σ y T dl n kT gas ≡ m c2 e,gas e e Z
• Amplitude of the kinetic SZ effect:
w β¯ τ = σ dl n β¯ , gas ≡ gas gas T e,gas gas Z
• Amplitude of the relativistic SZ effect:
τrel = σT dl ne,rel. Z Using the formalism of Enßlin & Kaiser (2000).
Unveiling the composition of plasma bubbles with the SZ-effect – p.7/15 Relativistic SZ effect We introduce a relativistic Comptonization parameter y˜:
δi (x) = [j(x) i(x)]τ = g˜(x)y˜, rel − rel where σ y˜ = T dl n kT˜ , m c2 e e e Z Pe kT˜e = , ne g˜(x) = [j(x) i(x)] β˜(kT˜ ) , − e 2 2 mec mec dl ne β˜(kT˜e) = = . kT˜ dl n kT˜ h ei Re e R
Unveiling the composition of plasma bubbles with the SZ-effect – p.8/15 Spectral distortions
frequency ν [GHz] 0 200 400 600
6
4
2 distortion 0 g(x) PSfrag replacements spectral h(x) -2 g˜UCRe(x) g˜CRe(x) -4 g˜50 keV(x) g˜20 keV(x) -6 0 2 4 6 8 10 12 14 = dimensionless frequency x hν/kTCMB
Unveiling the composition of plasma bubbles with the SZ-effect – p.9/15 Bubble model: visual
Pressure of the cooling core cluster is described by a multi- ple β-model, radio plasma bubbles are spheres cutting out the thermal pressure.
Unveiling the composition of plasma bubbles with the SZ-effect – p.10/15 Bubble model: mathematical
• Unperturbed line-of-sight (not intersecting the bubble), the observed thermal Comptonization parameter reads
(3βy,i 1)/2 N 2 2 − − x1 + x2 ycl(x1, x2) = yi 1 + 2 ry,i ! Xi=1
2 1 3βy,i 1 1 where y = σ (m c ) P r − , . i T e − i y,iB 2 2 • In the case of a line-of-sight intersecting the surface of the bubble, the area covered by the bubble reads
(3βy,i 1)/2 N 2 2 − − x1 + x2 yb(x1, x2) = ycl(x1, x2) yi 1 + 2 − ry,i ! Xi=1 z+ sgn(z) 1 3βy,i 1 qy,i(z) , − × 2 I 2 2 z − Unveiling the composition of plasma bubbles with the SZ-effect – p.11/15 A2052: SZE versus thermal X-rays
relative R.A. [arcsec] -40 -20 0 20 40 40
20
20 10 kpc] 1 − 70 h [ [arcsec]
0 0 Decl. e distance v e v
-10 relati relati -20
-20
-40 -20 -10 0 10 20 PSfrag replacements −1 relative distance [h70 kpc]
2.7 2.9 3.0 3.2 3.3
simulated GBT observation Chandra: 7600 7600 × ν = 90 GHz, size: 8000 8000 (Blanton et al., 2001) ×
Unveiling the composition of plasma bubbles with the SZ-effect – p.12/15 Perseus: SZE versus thermal X-rays
relative R.A. [arcsec] -60 -40 -20 0 20 40 60
60 20
40
10 kpc]
1 20 − 70 h [ [arcsec]
0 0 Decl. e distance v e
v -20
-10 relati relati -40
-20 -60
-20 -10 0 10 20 PSfrag replacements −1 relative distance [h70 kpc]
11.8 12.2 12.6 13.0 13.3
simulated ALMA observation Chandra: 60 60 × ν = 144 GHz, size: 2.50 2.50 (NASA/IoA/A.Fabian et al.) ×
Unveiling the composition of plasma bubbles with the SZ-effect – p.13/15 Unveiling the composition of bubbles
relative angular displacement [arcsec] relative angular displacement [arcsec] 0 20 40 60 80 100 0 20 40 60 80 100 2.0 ultra-relativistic CRe power-law CRe, e−– p – composition − + 16 power-law CRe, e – e – composition 1.8 = thermal electrons (kTe 50 keV) −
] 1
] = υ = + thermal electrons (kT 20 keV) 2 2 e gas 300 km s − − 1.6 arcmin arcmin 15 ultra-relativistic CRe − [mJy
[mJy − 1.4 power-law CRe, e – p – composition υ = + 1 − + gas 300 km s power-law CRe, e – e – composition = GHz) thermal electrons (kTe 50 keV) GHz) = 1.2 thermal electrons (kTe 20 keV)
14 217 144 ' =
0
0 -1.2 ν ν ( ( I I δ δ = −1 υgas 0 km s 13 -1.4 decrement
PSfrag replacements decrement PSfrag replacements flux
flux -1.6 − SZ 1 SZ υ = −300 km s 12 = − −1 gas υgas 300 km s -1.8
11 -2.0 0 10 20 30 40 0 10 20 30 40 −1 −1 relative distance [h70 kpc] relative distance [h70 kpc]
Unveiling the composition of plasma bubbles with the SZ-effect – p.14/15 Conclusions
• SZ effect offers suitable tool for studying plasma bubble composition (SZ effect more sensitive to cluster outskirts compared to X-rays)
• Observations of SZ cavities possible for non-thermal pressure supported bubbles: Perseus 5 hours exposure, A2052 30 hours exposure ∼ ∼ • Detailed observations will reveal the dynamically dominant composition (relativistic electrons, protons magnetic fields, hot thermal gas) Solving the cooling core riddle; indications how the heating mechanism→ proceeds by AGN bubbles Indications for AGN jet composition (leptonic versus → hadronic scenario)
Unveiling the composition of plasma bubbles with the SZ-effect – p.15/15