Another possible crisis for the standard cosmological model?

[Garth]

Another possible crisis for the standard cosmological model?
An old quasar in a young dark energy-dominated universe?

It is shown that for the currently accepted value of the matter density parameter, most of the existing dark energy scenarios cannot accommodate this old high redshift object unless the Hubble parameter is as low as H_o = 58km.s^-1.Mpc^-1, as recently advocated by Sandage and collaborators. Even considering less stringent age limits, only cosmological models that predicts a considerably old Universe at high z can be compatible with the existence of this object. This is the case of the conventional LambdaCDM scenario and some specific classes of brane world cosmologies.

Perhaps the universe is older than it is normally thought to be?
(for example: Freely Coasting Model?)
Garth

 

[hellfire]

In a free coasting model with H = 71 km/s Mpc the universe has the same age as in the standard model with H = 71 km/s Mpc (there is a difference of 0.1 Gyr between both). However, you are right, an object located at redshift 4 in the free coasting model is older (2.7 Gyr) than one at redshift 4 in the standard model (1.5 Gyr). There is a maximum in the difference in ages between both models around z ~ 3. By the way, how in which extent are these chemical evolution models widely accepted? I can imagine (just a feeling) that there are some assumptions behind them which may not be very stable (galactic evolution, mass functions, star formation rates, metalicities, etc.).

 

[Garth]

In a free coasting model with H = 71 km/s Mpc the universe has the same age as in the standard model with H = 71 km/s Mpc (there is a difference of 0.1 Gyr between both).

In the Freeely Coasting model, R ~ t, the age of the universe is Hubble time, H₀^-1, in the standard decelerating model it is less than this, in the Einstein - de Sitter model, R ~ t^2/3 the age of the universe is 2/3H₀^-1.

Of course the introduction of acceleration and dark energy completely changes the Einstein-de Sitter model, and can make the evolution of the universe, and its age, anything you want. Just keep switching it on and off! On for inflation, off for ancient cosmic evolution, on again for recent evolution since SN Ia, and possibly off again in the most recent epoch! However this arbitrary invocation robs the standard theory of any predictive power; you can make it predict anything you want, a big rip, a heat death, cosmic isolation, a big crunch, anything else you fancy?

However, you are right, an object located at redshift 4 in the free coasting model is older (2.7 Gyr) than one at redshift 4 in the standard model (1.5 Gyr). There is a maximum in the difference in ages between both models around z ~ 3. By the way, how in which extent are these chemical evolution models widely accepted? I can imagine (just a feeling) that there are some assumptions behind them which may not be very stable (galactic evolution, mass functions, star formation rates, metalicities, etc.).

I believe the Freely Coasting model is not as widely accepted as it should be as a viable alternative; however, there are a lot of problems to be resolved with it as well! Not least is finding a mechanism that delivers the linear expansion. One such theory does exist as you must know, Self Creation Cosmology, and that is being tested at the moment by Gravity Probe B.

We wait and see, exciting times!

Garth

 

[Chronos]

Our stellar evolution models are admittedly pretty weak, especially in the early universe where the action is hot and heavy, so to speak. Our knowledge of things like population III stars and hypernova is very limited. Early metallicity has been a source of debate for quite some time. It could be the universe is older than currently thought. This was also proposed as a possibility a few years ago:

http://arxiv.org/abs/astro-ph/0204505 :
Title: Detection of Iron Emission in the z = 5.74 QSO SDSSp J104433.04-012502.2
Authors: K. Aoki, T. Murayama, K. Denda

It is more often speculated that supernovae were produced more quickly and often in the early universe than suspected. Here are some papers on the subject:

http://arxiv.org/abs/astro-ph/0406636
Title: A New Contributor to Chemical Evolution in High-Redshift Galaxies
Authors: Takuji Tsujimoto

http://arxiv.org/abs/astro-ph/0307264
Title: Early star formation traced by the highest redshift quasars
Authors: R. Maiolino, Y. Juarez, R. Mujica, N. Nagar, E. Oliva

http://arxiv.org/abs/astro-ph/0306584
Title: FeII/MgII Emission Line Ratio in High Redshift Quasars
Authors: M.Dietrich, F.Hamann, I.Appenzeller, M.Vestergaard

http://arxiv.org/abs/astro-ph/0207005
Title: Discovery of an ionized Fe-K edge in the z=3.91 Broad Absorption Line Quasar APM 08279+5255 with XMM-Newton
Authors: G. Hasinger (1), N. Schartel (2), S. Komossa (1)

http://arxiv.org/abs/astro-ph/0109208
Title: High Redshift Quasars and Star Formation in the Early Universe
Authors: M. Dietrich, I. Appenzeller, M. Vestergaard, S.J. Wagner

http://arxiv.org/abs/astro-ph/9902361
Title: Chemical Evolution on the Scale of Clusters of Galaxies, and Beyond
Authors: Alvio Renzini

Iron production mechanisms other than supernova have also been occasionally suggested.

 

[ray b]

I have never like all or nothing events like ALL MATTER was created
in one big bang

why not a pre-existant univerce that had a big bang event
this allows some older bits to survive that we cannot account for
IE super massive BLACK HOLES
some heavy atoms [metal rich stars and quazars] ect
and would form a structure for the clumps we see now

are there any real facts the forbid any matter being here before the BIG BANG?

 

[Garth]

There could have been an earlier universe that went through some kind of bounce, which became our Big Bang, however the nuclear material would have been reprocessed during this process. The standard models uses the concordant nucleosynthesis of hydrogen, helium and trace other isotopes and elements from a primordial 'quark soup' as a 'verification pillar' of that theory. If atomic matter leaked through from the preceeding universe then that concordance would be compromised.

Garth

 

[turbo]

Our stellar evolution models are admittedly pretty weak, especially in the early universe where the action is hot and heavy, so to speak. Our knowledge of things like population III stars and hypernova is very limited. Early metallicity has been a source of debate for quite some time. It could be the universe is older than currently thought. This was also proposed as a possibility a few years ago

Thank you for the useful papers. I have many of them bookmarked already, but appreciate the citations to the ones I did not have. Indeed, the universe is probably much older than anyone can comprehend, and very old objects that we see in today's light are likely representative objects (at least as judged by local metallicities).

The interpretation of redshift as rigidly equivalent to distance (and cosmological expansion) is a problem that will cause our observations of quasars and other black-hole-like phenomena to be badly misrepresented. It's too bad that Einstein isn't around today, because he would have had the brain-power and the intellectual honesty to reconcile these. He HATED quantum theory, but by now, he would have said "OK, what do we need to do to GR to make it predictive in light of it?". His work has been enshrined (for decades), and there haven't been too many folks gutsy enough to question his assumptions. GR fails at galactic scales and at cluster scales. Some of the kids here (OK, I'm in my mid-50's, so most of you are "kids") will tackle these ideas and some of you will improve the assumptions of GR. Go for it!