Related papers: Subaru Telescope limits on cosmological variations…
Contemporary multidimensional cosmological theories predict different variations of fundamental physical constants in course of the cosmological evolution. On the basis of the QSO spectra analysis, we show that the fine-structure constant…
We statistically analyse a recent sample of data points measuring the fine-structure constant alpha (relative to the terrestrial value) in quasar absorption systems. Using different statistical techniques, we find general agreement with…
Detecting any evolution of dimensionless in the ratios of physical quantities, such as the fine structure constant, would prove that the Weak Equivalence Principle is violated and lead to a paradigm shift in physics. High resolution…
Detecting or placing upper limits on spacetime variations of fundamental constants requires quantifying every potential source of uncertainty. We continue our previous study into the impact of continuum variations on measurements of the…
We summarize the attempts by our group and others to derive constraints on variations of fundamental constants over cosmic time using quasar absorption lines. Most upper limits reside in the range 0.5-1.5x10-5 at the 3sigma level over a…
We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well…
We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars (23 doubles, 1 quad, and 1 possible triple, and 3 candidates) from the…
We present evidence for variations in the fine-structure constant from Keck/HIRES spectra of 143 quasar absorption systems over the redshift range 0.2 < z_abs < 4.2. This includes 15 new systems, mostly at high-z (z_abs > 1.8). Our most…
The detection of a spatial variation of the fine-structure constant, alpha, based on study of quasar absorption systems has recently been reported. The physics that causes this alpha-variation should have other observable manifestations,…
Aims. To obtain limits on the variation of the fine-structure constant alpha and the electron-to-proton mass ratio mu over different cosmological epochs. Methods. A new approach based on the comparison of redshifts of far infrared (FIR)…
This article reviews the two major recent developments that significantly improved cosmological measurements of fundamental constants derived from high resolution quasar spectroscopy. The first one is the deployment of astronomical Laser…
Spectra observed with the Ultraviolet and Visual Echelle Spectrograph (UVES) on the European Southern Observatory's VLT exhibit long-range wavelength distortions. These distortions impose a systematic error on high-precision measurements of…
Comparison of quasar absorption spectra with laboratory spectra allow us to probe possible variations in the fundamental constants over cosmological time-scales. In a companion paper we present an analysis of Keck/HIRES spectra and report…
The Keck telescope's HIRES spectrograph has previously provided evidence for a smaller fine-structure constant, alpha, compared to the current laboratory value, in a sample of 143 quasar absorption systems: da/a=(-0.57+/-0.11)x10^{-5}. This…
We present a short review of the current quasar (QSO) absorption line constraints on possible variation of the fine structure constant, alpha = e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra of 49 absorption…
The brighter-fatter effect affects all CCD sensors to various degrees. Deep-depleted thick sensors are seriously affected and the measurement of galaxy shapes for cosmic shear measurements requires an accurate correction of the effect in…
We have previously presented 5.7-sigma evidence for a smaller alpha at redshifts 0.2 < z_abs < 3.7 from a sample of 128 Keck/HIRES quasar absorption systems: da/a = (-0.57 +/- 0.10) x 10^{-5}. A non-zero da/a manifests itself as a distinct…
Cosmological variation of the fine structure constant $\alpha$ due to the evolution of a spatially homogeneous ultra-light scalar field ($m \sim H_0$) during the matter and $\Lambda$ dominated eras is analyzed. Agreement of $\Delta…
Searches for variations of fundamental constants require accurate measurement errors. There are several potential sources of errors and quantifying each one accurately is essential. This paper addresses one source of uncertainty relating to…
High resolution spectra of quasar absorption systems provide the best constraints on temporal or spatial changes of fundamental constants in the early universe. An important systematic that has never before been quantified concerns model…