Debate: the Values of Cosmic Parameters
H0 | q0 | Om | OL | Ob
Topics to Investigate: Observational Constraints
- H0 from direct measurements (e.g., HSTKP)
- q0 from type Ia supernovae (e.g., Hi-z;
- Age constraints [f(q0,1/H0)] from globular clusters
- Omegab from deuterium & other light element abundances
- Omegam from
- large scale structure (e.g., 2dF;
- cluster baryon fractions (e.g., Evrard)
- cluster mass-to-light ratios (e.g., BCDO; CNOC)
SHF combine several of these
- OmegaLambda from gravitational lensing statistics (e.g.,
- Omegam + OmegaLambda from the cosmic microwave
background (e.g., Boomerang; Maxima-1;
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 "Obh2 = 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.
Schedule of talks
- 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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