Determination of cosmic distance from SunyaevZelDovich effect

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Determination of cosmic distance from
Sunyaev-ZelDovich effect

• Bingxiao Xu
• December, 6th

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OUTLINE

• Introduction of SZE
• Basic principle of SZE method to measure the
  distance
• Recent distance measurement results
• Discussion and conclusion

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Sunyaev-ZelDovich Effect(SZE)
Sunyaev
Zel Dovich
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Basic idea

• The low energy photons travel through the hot
  electrons and are boosted to high energy photons
  (inverse Compton scattering)
• CMB (2.7K) ? Galaxy clusters (T107K)

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CMB will be shifted up !
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Galaxy cluster

• Hot gas with T107 K
• Strong X-ray source (thermal Bremsstrahlung)

EMSS 13586245 ?
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Spherical assumption for cluster

• Easily model the structure of cluster
• Convert line-of-sight distance to angular size

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Basic principle of SZE method to measure the
distance

• Different density dependence of CMB temperature
  decrement and X-ray surface brightness

Angular distance
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Two important parameters

• CMB temperature decrement (interferometric radio
  observations)
• e.g. BIMA,OVRO typical AR 1)
• X-ray temperature profile for cluster
• (High resolution X-ray observations)
• e.g. XMM-Newton, Chandra.
• typical AR 0.5

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Process

• Get initial observational data (SZE map, X-ray
  image)
• Establish proper model (density profile, thermal
  emissivity,)
• Obtain best fit to the parameters
• Use that formula to get the distance value

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Recent results (Reese et. al. 2002)

• Sample number 18
• SZE observation BIMA,OVRO
• X-ray observation ROSAT

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X-ray image plus SZE contour
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Final results
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Hubble constant determination
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More recent one(Bonamente et. al. 2006)

• Sample number 38 (the largest so far)
• SZE observation BIMA, OVRO
• X-ray observation Chandra (ACIS detectors)

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Data
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Image and profile
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Final results
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Hubble constant determination
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Discussion conclusion

• SZE method is a absolute distance estimator
• Insensitive to the plasma physics and redshift
  (good news!)
• Many uncertainties involved such as asphericity,
  point source contamination (for SZE),Galactic
  N_H1, (bad news!)
• SZE survey (more distant, more accurate.)

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Reference

• Sunyaev, R. Zeldovich, Y. 1970, Comments
  Astrophys. Space Phys., 2, 66
• Calstrom,J., Holder, G. Reese, E. ARAA,
  2002, 40, 643
• Reese, E., et al. ApJ, 2002, 581, 53
• Bonamente, M., et al. ApJ, 2006, 647, 25
• Chandra Proposers Observatory Guide,
  http//asc.harvard.edu/proposer/POG/html