Related papers: High-precision limit on variation in the fine-stru…

We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500 - 920 $\AA$) of high luminosity quasars using HST (low to intermediate redshift sample) and SDSS (high redshift sample) archives. The combined HST and SDSS data…

(abridged) We present a new analysis of a large sample of quasar absorption-line spectra obtained using UVES (the Ultraviolet and Visual Echelle Spectrograph) on the VLT (Very Large Telescope) in Chile. In the VLT sample (154 absorbers), we…

Cosmological variations in the fine structure constant, alpha, can be probed through precise velocity measurements of metallic absorption lines from intervening gas clouds seen in spectra of distant quasars. Data from the Keck/HIRES…

Theories unifying gravity with other interactions suggest spatial and temporal variation of fundamental ``constants'' in the Universe. A change in the fine structure constant, alpha, could be detected via shifts in the frequencies of atomic…

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 [O III] $\lambda\lambda\ 4960,5008$ emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constant $\alpha$ over cosmic time. In this work, we…

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…

In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along background quasar sight-lines, reporting…

We present an analysis of the absorption-line system in the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph spectrum at a redshift of $z_{\rm a}={3.1448}$ associated with the quasar SDSS J122040.23+092326.96, whose…

We propose a new methodology for probing the cosmological variability of alpha from pairs of FeII lines (SIDAM, single ion differential alpha measurement) observed in individual exposures from a high resolution spectrograph. By this we…

We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10,000…

Observations of the redshift z=7.085 quasar J1120+0641 have been used to search for variations of the fine structure constant, alpha, over the redshift range 5.5 to 7.1. Observations at z=7.1 probe the physics of the universe when it was…

From the Sloan Digital Sky Survey (SDSS) Data Release 12, which covers the full Baryonic Oscillation Spectroscopic Survey (BOSS) footprint, we investigate the possible variation of the fine-structure constant over cosmological time-scales.…

We have compared the frequency of high-redshift Hydrogen HI 21 cm absorption with that of associated molecular absorption in two quasars to place new (1 sigma) upper limits on any variation in y = g_p.alpha^2 (where alpha is the fine…

Recent quasar spectroscopy from the VLT and Keck telescopes suggests that fundamental constants may not actually be constant. To better confirm or refute this result, systematic errors between telescopes must be minimized. We present a new…

We present the results of a search for variability in the equivalent widths (EWs) of narrow, associated (Delta v < 5,000 km/s) absorption lines found in the UV spectra of z < 1.5 quasars. The goal of this search was to use variability as a…

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…

The most precise method of investigating possible space-time variations of the fine-structure constant, using high-redshift quasar absorption lines, is the many-multiplet (MM) method. For reliable results this method requires very accurate…

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…

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)…