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Garth

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**An Old quasar in a Young Universe?**

On the arXiv today:Age of High Redshift Objects - a Litmus Test for the Dark Energy Models The Abstract:

(Italics mine)The discovery of the quasar, the APM 08279+5255 at z = 3.91 whose age is 2.1 Gyr has once again led to “age crisis”. The noticeable fact about this object is that it cannot be accommodated in a universe with Omega_m = 0.27, currently accepted value of matter density parameter and w = constant. In this work, we explore the concordance of various dark energy parameterizations (w(z) models) with the age estimates of the old high redshift objects. It is alarming to note that the quasar cannot be accommodated in any dark energy model even for Omega_m = 0.23, which corresponds to 1 sigma deviation below the best fit value provided by WMAP.There is a need to look for alternative cosmologies or some other dark energy parameterizations which allow the existence of the high redshift objects.

Just for the record, in the SCC scenario, in the Einstein conformal frame with constant atomic proper masses, the age of the universe at z = 3.91 is 2.8 Gyrs. The authors quote their eprint Cosmological Constraints on a Power Law Universe . Abstract.

Here we go again?Linearly coasting cosmology is comfortably concordant with a host of cosmological observations. It is surprisingly an excellent fit to SNe Ia observations and constraints arising from age of old quasars. In this article we highlight the overall viability of an open linear coasting cosmological model.The model is consistent with the latest SNe Ia ``gold'' sample and accommodates a very old high-redshift quasar, which the standard cold-dark model fails to do.

Garth

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