Incompatibility of a comoving Lyαforest with supernova-Ia luminosity distances

Abstract

Recently, Perlmutter et al. (1999) suggested a positive value of Einstein's cosmological constant Λ on the basis of luminosity distances from type-Ia supernovae (the "SN-method"). However, Λ world models had earlier been proposed by Hoell & Priester (1991) and Liebscher et al. (1992a,b) on the basis of quasar absorption-line data (the "Q-method"). Employing more general repulsive fluids ("dark energy") encompassing the Λ component, we quantitatively compare both approaches. Fitting the SN-data by a minimum-component model consisting of dark energy + dust (pressureless matter) yields a closed universe with a large amount of dust exceeding the baryonic content constrained by big-bang nucleosynthesis. The nature of the dark energy is hardly constrained. Only when enforcing a flat universe is there a clear tendency to a dark-energy Λ fluid and the "canonical" value ΩM ≈ 0.3 for dust. Conversely, a minimum-component Q-method fit yields a sharply defined, slightly closed model with a low dust density ruling out significant pressureless dark matter. The dark-energy component obtains an equation-of-state P = −0.96 close to that of a Λ-fluid (P = −). ΩM = 0.3 or a precisely flat spatial geometry are inconsistent with minimum-component models. It is found that quasar and supernova data sets cannot be reconciled with each other via (repulsive ideal fluid+incoherent matter+radiation)-world models. Compatibility could be reached by drastic expansion of the parameter space with at least two exotic fluids added to dust and radiation as world constituents. If considering such solutions as far-fetched, one has to conclude that the Q-method and the SN-Ia constraints are incompatible.

Wolfgang Priester: from the big bounce to the $\Lambda$-dominated universe

“…We will not go over this material in detail here; recent reviews may be found in [107] and [142]. Instead, we will approach the phenomenon of quasar absorption lines in a different way and focus on what is probably the "Achilles heel" of the BN-P approach: its assumption that intrinsic evolution in the absorber population can be neglected relative to the Hubble expansion rate.…”

“…The study of these issues occupied most of the last ten years of Wolf's career, including two more review articles in Naturwissenschaften, a chapter in the authoritative Bergmann-Schaefer Lehrbuch der Experimentalphysik and many more publications [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109]. We will not go over this material in detail here; recent reviews may be found in [107] and [142]. Instead, we will approach the phenomenon of quasar absorption lines in a different way and focus on what is probably the "Achilles heel" of the BN-P approach: its assumption that intrinsic evolution in the absorber population can be neglected relative to the Hubble expansion rate.…”

Quasar Absorption-Line Number Density in a Closed, Λ-Dominated Universe

“…1(b). We do not discuss the details of this model here (see Liebscher, Kayser and Helbig, 1996;Thomas and Schulz 2001 for critical reviews), except to note that it was derived from Lyα absorption-line statistics under the assumption that evolutionary effects could be neglected. Insofar as this assumption is justified, the present results can be seen as a confirmation of this earlier work, which was based on a significantly older dataset and a completely independent method of analysis.…”