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The SZE in groups of galaxies

The SZE in groups of galaxies. Why?. How?. Normal groups (overdensity ≈ 200). half of galaxies are in groups. laboratory for environmental effects. transition from clusters to single galaxies building blocks of clusters. Compact groups (overdensity ≈ 10 5 ).

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The SZE in groups of galaxies

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  1. The SZE in groups of galaxies Why? How? Gary MAMON, ALMA-SZ workshop, 8 April 2005

  2. Normal groups (overdensity ≈ 200) half of galaxies are in groups laboratory for environmental effects transition from clusters to single galaxies building blocks of clusters Compact groups (overdensity ≈ 105) densest galaxy densities in Universe laboratory for extreme environmental effects heavy contamination by projection effects? are many CGs = chance alignments of galaxies? within normal groups, clusters, filaments Mamon 86 Walke & Mamon 89 Hernquist et al. 95 Groups of galaxies massive clusters rare at high z! Gary MAMON, ALMA-SZ workshop, 8 April 2005

  3. Science with SZ in Groups Quantify alignment along line of sight Internal structure Evolution of group gas properties but can’t measure T at medium to high z! Better stats on n(z) to constrain cosmology Gary MAMON, ALMA-SZ workshop, 8 April 2005

  4. intergalactic gas in hydrostatic equilibrium with group potential X-ray emission traces gravitational potential X-rays less subject to projections 30-80% of CGs have diffuse X-ray emission ROSAT, ASCA Mulchaey et al. 96; Ponman et al. 96 Can X-rays settle the alignment debate? Gary MAMON, ALMA-SZ workshop, 8 April 2005

  5. HCG 62 Vrtilek et al. 00 HCG 16 Mamon et al. unpub Compact groups in X rays Gary MAMON, ALMA-SZ workshop, 8 April 2005

  6. Luminosity - Temperature relation Osmond & Ponman 04 groups clusters Gary MAMON, ALMA-SZ workshop, 8 April 2005

  7. Unresolved groups If V ≈ a2 c } gas mass / alignment degeneracy Ostriker et al. 95 can be lifted by SZ measurements Do X-rays measure gas mass? Gary MAMON, ALMA-SZ workshop, 8 April 2005

  8. 300 x lower Groups vs Rich Clusters 1013 Msun 1015 Msun 1000 x lower Gary MAMON, ALMA-SZ workshop, 8 April 2005

  9. 1 detection at South Polar Telescope in 4.5 hr 3 detection at South Polar Telescope in 40 hr! Observability: 1) sensitivity ygroups ≈ 5 x 10-7 1013 Msun better with ALMA if we smooth y maps? stack groups Planck/1yr  3 x 1013 Msun Gary MAMON, ALMA-SZ workshop, 8 April 2005

  10. Observability: 2) angular size 1013 Msun M*(z) = M ALMA will resolve groups at all redshifts but not detect them unless one smoothes the map? SPT will barely resolve groups at all redshifts Gary MAMON, ALMA-SZ workshop, 8 April 2005

  11. Conclusion Relative to clusters, groups are more visible in SZ than in X-rays But, because of lack of sensitivity of SZ instruments (relative to X-ray instruments), groups are extremely hard to detect, even with ALMA or SPT Gary MAMON, ALMA-SZ workshop, 8 April 2005

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