Ekpyrotic model and CMB observations?

[branebrain]

Hello folks,

I'm new to this fine forum and wondered if anyone here knows which present or future spacecraft (perhaps even balloon borne mission?) are capable of discriminating the effects of the strongly blue shifted gravitational spectrum that should be evident in the CMB as the Ekpyrotic model predicts? What exactly are the signatures in the CMB? Microwave polarizations? Any info on the latest data in this area would be greatly appreciated.

bb

[marcus]

Hello branebrain, welcome from one of the rank-and-file,
one or more of the PF Mentors will probably be saying hello
and may respond to your question

I can't reply specifically but I just happened across a
new paper by Eric Linder that suggests the possibility of
testing various models by their signature on the history
of accelerated expansion.

I started a thread about Linder's article
http://www.physicsforums.com/showthread.php?s=&threadid=15078
and called the thread "different kinds of dark energy"

He was comparing a "braneworld" hypothesis with a "cosmological constant" hypothesis and seeing if they predicted detectably different grow curves for the size of the universe. (His braneworld model may not be your ekpyrotic picture but could interest you all the same.)

Can you provide a link to some article about how the ekpyrotic model would leave a signature effect on the CMB? It is interesting to know about proposed means for testing these various models.

Linder's article is not about the CMB but about the supernova redshift-distance data, but in case you are interested in looking at it Linders is

http://arxiv.org/abs/astro-ph/0402503

or its at that other thread.
I dont know how branes get into it for Linder, but he is a well-known cosmologist and generally has something interesting to say.

[branebrain]

Hello marcus,

Here are three links that may help regarding the stochastic gravitational background and its signature on the CMB:

http://arxiv.org/pdf/astro-ph/0302012
http://arxiv.org/pdf/astro-ph/0112381
http://nedwww.ipac.caltech.edu/level5/March03/Lineweaver/Lineweaver6.html



I'm enjoying your links regarding Type 1a supernova results and the constraints placed on Inflation and cyclic models.

Thanks,
bb

[marcus]

Your 3rd link is to the Caltech HTML version of Lineweaver's great article
If you ever want PDF it is at
http://arxiv.org/astro-ph/0305179
your link is to page 19 of the PDF print-out
section "6. The Status of Inflation"

I'm a fan of Lineweaver

there are more lineweaver links and other goodies
at the "Reference Shelf" sticky

(you may know all this and I may not be telling you anything"

I looked at your first link

Koury, Steinhardt, and Turok

I cant figure out how soon anything will be testable from
the CMB spectrum, regarding these different models.
something to keep alert to, I guess, but not to expect results soon.
sorry cant respond more cogently

Nereid often knows things. Try to get her attention.