Dark energy is the invisible fuel that seems to drive the current acceleration of the Universe .
Its presence , which is inferred from an impressive convergence of high-quality observational results along with some apparently sucessful theoretical predictions , is also supported by the current estimates of the age of the Universe from dating of local and high- z objects .
In this paper we test the viability of several dark energy scenarios in the light of the age estimates of the high redshift ( z = 3.91 ) quasar APM 08279+5255 .
Using a chemodinamical model for the evolution of spheroids , we first reevaluate its current estimated age , as given by Hasinger et al .
( 2002 ) .
An age of 2.1 Gyr is set by the condition that Fe/O abundance ratio ( normalized to solar values ) of the model reaches 3.3 , which is the best fit value obtained in the above reference .
In the detailed chemodynamical modelling , the iron enrichment defines three relevant time scales : ( i ) \sim 0.3 Gyr for the central region of the galaxy housing the quasar to reach a solar iron abundance ; ( ii ) \sim 1 Gyr for the Fe/O abundance ratio to reach the solar value ; ( iii ) \sim 2 Gyr for a highly suprasolar Fe/O abundance ratio ( Fe/O=2.5 , suggested by the quasar APM 08279+5255 ) .
Therefore , a high value of the Fe/O abundance ratio for a quasar is a strong evidence that the quasar is old , which represents a severe constraint for cosmological scenarios .
It is shown that for the currently accepted value of the matter density parameter , most of the existing dark energy scenarios can not accomodate this old high redshift object unless the Hubble parameter is as low as H _ { o } = 58 { km . 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 \Lambda CDM scenario and some specific classes of brane world cosmologies .