kinetic sz effect from galaxy cluster rotation & another relativistic correction to the sze jc,...

Kinetic SZ effect from galaxy cluster rotation&

Another relativistic correction to the SZE

JC, Gert Hütsi and Rashid Sunyaev

accepted by A&A, 2005, astro-ph/0409058

Max-Planck-Institut für Astrophysik

Jens Chluba and Karl Mannheim

A&A 396, 419-428 (2002)

Universitäts-Sternwarte Göttingen

Kinetic SZ effect from

galaxy cluster rotation

Large & smalle scale motion of the ICM

SZ effect and Alma workshop - Orsay - April 2005 - Jens Chluba - MPA-Garching

• Mergers in the cosmological context

should excite large & small scale motion of the ICM ! (off-axis mergers)

• Coma Cluster (XMM)

(Schuecker et al., 2004) turbulent motions on scales ~20-145 kpc (core radius 420 kpc) turbulence on larger scalesis possible!

• Turbulent cascades• from large small scales• viscosity• plasma instabilities• magnetic fields• transition between k-SZ & th-SZ

Schuecker et al., 2004

Large & smalle scale motion of the ICM (2)

• Hydrodynamic simulations by Norman & Bryan 1999 turbulent velocities ~ 25-60% of virial velocity minor mergers maintain the level of turbulence also found „ordered“ circulation, which is likely due to a off-axis merger

• X-ray spectral lines for Centaurus cluster (Dupke & Bregman 2001)

bulk velocities of the order of ~1000 km/s likely due to a previous off-axis merger

• Several recent hydrodynamic simulations (Nagai et al. 2003; Torman, Moscardini & Yoshida 2004; Diaferio, Borgani, Moscardini et al. 2005)

bulk velocities v ~ few 100 km/s


Toy-model for large scale motion of the ICM

• Initial stage after (major) merger one large scale eddie simple assumption: solid body rotation line of sight velocity constant

• Gas follows isothermal -model line of sight integral analytical

• spectral dependence like k-SZ• dipolar signature (inclination)• extrema at y ~ few rc

• core ~ 10-5 to few 10-4

T ~ 0.1 - few 10 µK

)sin( 1

ccore r

y

e

ex

I

Ix

x

=0.75, =90°, Rmax= 10 rc


Multi-frequency observations of the SZE

• Main signals th-SZ and k-SZ

• RJ part of the CMB spectrum th-SZ dominant

• close to cross-over frequency k-SZ + rk-SZ

• shift of the maximum: y ~ fraction of the core radius optimistic: y ~ few arcsec even more optimistic: y up to arcmin (no k-SZ)

• Comparison of SZ image at different frequencies• This probably also happens for two merging lumps

• linear polarization many orders smaller (few nK or a fraction of µK level) sensitive to the transverse velocity optimistic: on the level of a few % relative to the k-SZ polarization k-SZ + rk-SZ tilt of the planes of polarization by a few degree frequency-independent (in principle separable from e.g. multiple scattering for rich clusters...)


Another relativistic correction to the SZE....

SZ effect from clusters of galaxies

• Relativistic temperatures & peculiar motions (Rephaeli, 1995;

Challinor & Lasenby 1998; Sazonov & Sunyaev, 1998; Itoh et al., 1998) corrections to the lowest order signals especially important at high frequencies 10-20% deviations possiblility to measure the electron temperature only with the CMB (strong frequency dependence)

• non-thermal SZ

• Motion of the Solar System ! (Chluba, Hütsi &

Sunyaev, 2004) • has been neglected so far• SZ effect: imprint in the CMB rest frame• Doppler boosting & aberration• Lorentz boosted y-distortion correction similar to

the first order temperature correction to the k-SZ

• easy to take into account!


Motion-induced Change of SZ Brightness

• Example kTe= 5.1 keV, c = 10-3 and o = 1.241 10-3

• strong frequency and spatial dependence• can reach the level of 10% of the k-SZ at high frequencies (e.g.14% at 400 GHz)

• RJ- limits: motion-induced correction to th-SZ: T/T=-2 y o


• simple analytic model for k-SZ from cluster rotation• dipolar signature on few 10 arcsec angular scales close to center• T ~ 0.1 - few 10 µK• comparing multi-fequency morphology may be useful• combined with polarization very useful to constraint motions of ICM• turbulent motions interesting contribution to th-SZ (transition)

• motion-induced correction to the th-SZ similar to the first order temperature correction to the k-SZ

• strong spectral & spacial dependence• reaches the 10% level of the k-SZ• easy to take into account !!!• Dipolar asymmetry of the cluster number counts (1% level)

Conclusions

kinetic sz effect from galaxy cluster rotation & another relativistic correction to the sze jc,...

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