[astro-ph/0509212] Age of High Redshift Objects - a Litmus Test for the Dark Energy Models

Authors:  Deepak Jain, Abha Dev
Abstract:  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 $\omega = \mathrm{constant}$. 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.
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Garth Antony Barber
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[astro-ph/0509212] Age of High Redshift Objects - a Litmus T

Post by Garth Antony Barber » September 09 2005

Any comments on these extraordinary claims?

Boud Roukema
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Re: [astro-ph/0509212] Age of High Redshift Objects - a Litm

Post by Boud Roukema » September 09 2005

Garth Antony Barber wrote:Any comments on these extraordinary claims?
The title is not so extraordinary: this is a good type of test. But the interesting question is how precise the 2.1Gyr estimate is.

If this estimate were 2.1 ± 0.1 Gyr (no h dependence) including random and systematic error, then it would start to become significantly (several sigma) in contradiction with the concordance values of the local cosmological parameters (e.g. 71,0.27,0.73,−1.0).

If it's 2.1 ± 0.5 Gyr (no h dependence) then it's not yet precise enough.

From a 5 minute scan of Hamann & Ferland (1993) + Komossa & Hasinger (2002) it is not obvious to me that we have 2.1 ± 0.1 Gyr (no h dependence), but maybe that's simply because 5 minutes is not enough. If you are interested, then please read the papers, understand them, and then you can summarise for us. :)

Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

[astro-ph/0509212] Age of High Redshift Objects - a Litmus T

Post by Garth Antony Barber » September 09 2005

Yes, the age is determined from the Fe/O and Fe/Ne relative abundances and it takes time to form Fe in the observed quantities; Fe/O ~ 3. It would be essential to firm up on the error bars of this age determination for APM08279+5255, is there any more recent information about this?

Jain & Dev seem to have pulled the value of 2.1 Gyr out of thin air, with no error bars at all. Is this a generally accepted value for that system or have they just 'made it up'?

Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

[astro-ph/0509212] Age of High Redshift Objects - a Litmus T

Post by Garth Antony Barber » September 11 2005

In answer to my last question I found http://www.ingentaconnect.com/content/b ... 4/art00002
"Cosmological implications of APM 08279+5255, an old quasar at z= 3.91" Alcaniz J.S.; Lima J.A.S.; Cunha J.V, MNRAS, Volume 340, Number 4, April 2003, pp. L39-L42(1)
The existence of old high-redshift objects provides an important tool for constraining the expanding age of the Universe and the formation epoch of the first objects. In a recent paper, Hasinger, Schartel & Komossa reported the discovery of the quasar APM 08279 + 5255 at redshift z= 3.91 with an extremely high iron abundance, and estimated age of 2−3 Gyr. By assuming the lower limit for this age estimate and the latest measurements of the Hubble parameter as given by the HST key project, we study some cosmological implications from the existence of this object. In particular, we derive new limits on the dark matter and vacuum energy contribution. Our analysis is also extended to quintessence scenarios in which the dark energy is parametrized by a smooth component with an equation of state px= x x (−1 x < 0) . For flat models with a relic cosmological constant we show that the vacuum energy density parameter is constrained to be 0.78 , a result that is marginally compatible with recent observations from type Ia supernovae (SNe Ia) and cosmic microwave background (CMB). For quintessence scenarios the same analysis restricts the cosmic parameter to x −0.22 . Limits on a possible first epoch of quasar formation are also briefly discussed. The existence of this object pushes the formation era back to extremely high redshifts.
(emphasis mine)

So it looks as if Jain and Dev we quoting the lower end of that age range, with a possible lower error of −0.1 Gyr. May their conclusions therefore be of some significance?

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