Dark Energy increasing with Time:

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Active galaxies point to new physics of cosmic expansion:

January 29, 2019, European Space Agency:

Investigating the history of our cosmos with a large sample of distant 'active' galaxies observed by ESA's XMM-Newton, a team of astronomers found there might be more to the early expansion of the universe than predicted by the standard model of cosmology.

According to the leading scenario, our universe contains only a few percent of ordinary matter. One quarter of the cosmos is made of the elusive dark matter, which we can feel gravitationally but not observe, and the rest consists of the even more mysterious dark energy that is driving the current acceleration of the universe's expansion.

This model is based on a multitude of data collected over the last couple of decades, from the cosmic microwave background, or CMB – the first light in the history of the cosmos, released only 380,000 years after the big bang and observed in unprecedented detail by ESA's Planck mission – to more 'local' observations. The latter include supernova explosions, galaxy clusters and the gravitational distortion imprinted by dark matter on distant galaxies, and can be used to trace cosmic expansion in recent epochs of cosmic history – across the past nine billion years.

Read more at:


the paper:

Cosmological constraints from the Hubble diagram of quasars at high redshifts:


The concordance model (Λ cold dark matter (ΛCDM) model, where Λ is the cosmological constant) reproduces the main current cosmological observations1,2,3,4 assuming the validity of general relativity at all scales and epochs and the presence of CDM and of Λ, equivalent to dark energy with a constant density in space and time. However, the ΛCDM model is poorly tested in the redshift interval between the farthest observed type Ia supernovae5 and the cosmic microwave background. We present measurements of the expansion rate of the Universe based on a Hubble diagram of quasars. Quasars are the most luminous persistent sources in the Universe, observed up to redshifts of z ≈ 7.5 (refs. 6,7). We estimate their distances following a method developed by our group8,9,10, based on the X-ray and ultraviolet emission of the quasars. The distance modulus/redshift relation of quasars at z < 1.4 is in agreement with that of supernovae and with the concordance model. However, a deviation from the ΛCDM model emerges at higher redshift, with a statistical significance of ~4σ. If an evolution of the dark energy equation of state is allowed, the data suggest dark energy density increasing with time.

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I wouldn't place too much faith on this paper in and of itself, while its findings are interesting I personally feel it isn't conclusive enough by itself to overturn the constant of Lambda. It is noteworthy but it will most likely take further studies to test its robustness. Over the years I have seen numerous papers suggesting findings of an evolving Lambda but they are in essence insufficient in the face of the evidence for the constancy of Lambda.

grr there was something I should be remembering at roughly Z=4.5 to 5.5, I'll have to see if I can remember what it was but if I recall it had to do with apparent luminosity. Anyways that's just my inside voice typing...

Found a related in regards to my inside voice an older study of  the QLF quasar luminosity function at z>5, this papers discusses some of the corrections that need to apply in some of the findings they had. In essence trying to solve why two different findings of the same quasars had two different results in the Lyman alpha forest findings.


Edited by Mordred

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