Topics to Investigate: Observational Constraints

• H₀ from direct measurements (e.g., HSTKP)
• q₀ from type Ia supernovae (e.g., Hi-z; SCP)
• Age constraints [f(q₀,1/H₀)] from globular clusters (e.g., VSB)
• Omega_b from deuterium & other light element abundances (e.g., Olive; TOSL)
• Omega_m from
  • kinematics
  • large scale structure (e.g., 2dF; 2dF-lite)
  • cluster baryon fractions (e.g., Evrard)
  • cluster mass-to-light ratios (e.g., BCDO; CNOC)
    SHF combine several of these
• Omega_Lambda from gravitational lensing statistics (e.g., CQM; K)
• Omega_m + Omega_Lambda from the cosmic microwave background (e.g., Boomerang; Maxima-1; DASI)

Also see the extended reference list for further pointers.

A brief discussion combining many of these topics is given by
The Observational Case for a Low Density Universe with a Non-Zero Cosmological Constant
Ostriker & Steinhardt 1995, Nature, 377, 600
I will lead a discussion of this paper to launch our more detailed discussion of the individual observational constraints.

Note that many of the observational constraints often boil down to a statement like "O_bh² = 0.019 +/- 0.001." This is the essence of what you're after, though of course you need to understand the method in order to appreciate how the result is obtained and what might go wrong. But we will need something like this as a bottom-line answer for intercomparison of results in the culminating debate.

Tentative schedule:

Wed April 3: Choice of topics DUE

Let me know what you plan to investigate and present.

Wed 17 April: Discussion of Ostriker & Steinhardt

Led by McGaugh

Wed 24 April: Written repots DUE

Make 14 copies - one for everybody.

There is no page length requirement. Use what space is needed to get the basic point accross to your colleagues. I'd guess that 3 or so pages of text would generally be adequate, but more space may be needed for figures and references. The purpose is to illustrate what cosmological constraint a particular observation imposes and how it does so in as digestible a format as possible. Remember: you'll get a dozen of these to read yourself!

Mon 22 April: Student talks

Wed 24 April: Student talks

Mon 29 April: Student talks

Tue 23 or 30 April: Student talks (replacement for displaced March 11 class.)

Talks will be 20 minutes each.

A specific schedule will be constructed in early April.

Choose a topic to investigate. The list above is intended as a guide to some of the important topics, but there are plenty of other possibilities. Let me know by Wed April 3 what you'd like to investigate. While there are many possibilities, I will try to ensure that a diversity of topics are covered, so if anything proves particularly popular it will go on a first come-first serve basis.

Mon 29 or Tue 30 April: Secret ballot

Choose sides! does it all add up?

Wed 1 May: Debate

I am still unclear on how this will actually work. I think I will try to provide a summary at the end of all the talks, after which we'll have a secret ballot. The idea is to choose sides for or against the standard LCDM cosmology/parameter values as outlined by Ostriker & Steinhardt. I will use the ballots to line up debate teams who will face off on May 1. In the event of a lopsided vote one way or the other, I will take the role of opposing the majority.

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