The Sunyaev-Zeldovich effect (SZ effect or Sunyaev-Zeldovich theory) is due to high energy electrons distorting the cosmic microwave background radiation (CMB) through the inverse Compton effect, in which some of the high energy of the electrons is transferred to the low energy photons. It determines disk accretion and photon-electron scattering . This inverse Compton effect between the photons and electrons alters the CMB spectrum observed. This has been observed through many telescopes, for example XMM-Newton.

The Sunyaev-Zeldovich theory can be divided into:

• thermal effects
• kinetic effects
• polarization

Sunyaev and Zeldovich predicted the effect, and conducted research in 1969, 1972, and 1980. The Sunyaev-Zeldovich effect is of major astrophysical and cosmological interest. It can help determine the value of the Hubble constant.

To distinguish the SZ effect due to galaxy clusters from ordinary density perturbations, both the spectral dependence and the spatial dependence of fluctuations in the cosmic microwave background are used. Analysis of CMB data at higher angular resolution (high l values) requires taking into account the Sunyaev-Zeldovich effect.

Current research is focused on modelling how the effect is generated by the intra-cluster plasma in galaxy clusters, in using the effect to estimate the Hubble constant and to separate different components in the angular average statistics of fluctuations in the background. Hydrodynamic structure formation simulations are being studied to gain data on thermal and kinetic effects in the theory. Observations are difficult due to the small amplitude of the effect and to confusion with experimental error and other sources of CMB temperature fluctuations.

See also: Background radiation, Compton effect, Cosmic background radiation, Cosmic microwave background radiation, Rashid Sunyaev, Yakov Zel'dovich

External links and references

• Myers et al, "Evidence for an Extended SZ Effect in WMAP Data". 2004 RAS Press Release Images.
  • Myers, A. D., T. Shanks, P. J. Outram, W. J. Frith, and A. W. Wolfendale, "Evidence for an Extended SZ Effect in WMAP Data". Astrophysics, astro-ph/0306180.
• Birkinshaw, Mark, "The Sunyaev Zeldovich Effect", Department of Physics, University of Bristol, Bristol, UK.
• Ma, Chung-Pei, and J. N. Fry, "Nonlinear Kinetic Sunyaev-Zeldovich Effect". PRL. May 27 2002. (arXiv.org)
• Sunyaev, R. A. and Ya. B. Zeldovich, "Small-Scale Fluctuations of Relic Radiation". Astrophysics and Space Science, Vol. 7, p.3, 1970.
• Sunyaev, R. A.; Zeldovich, Ia. B. "Microwave background radiation as a probe of the contemporary structure and history of the universe". Annual review of astronomy and astrophysics. Volume 18. Palo Alto, California. 1980.
• Hu, Jian, and Yu-Qing Lou, "Magnetic Sunyaev-Zeldovich effect in galaxy clusters". ApJL.
• "Matter-antimatter asymmetry". Phys199 course. hep.caltech.edu (PDF)
• Cen, Renyue, and Jeremiah P. Ostriker, "A hydrodynamic approach to cosmology: the mixed dark matter cosmological scenario". The Astrophysical Journal, 431, (1994), 1.
• Springel, Volker, Martin White, and Lars Hernquist, "Hydrodynamic Simulations of the Sunyaev-Zel'dovich effect(s)". ApJ.