258 citations · 590 across the 14 of their papers we have counts for
7 papers · 1 filter
Most precise single redshift bound to the variability of the fine-structure constant
S. A. Levshakov, M. Centurion, P. Molaro +4
Verification of theoretical predictions of an oscillating behavior of the fine-structure constant, alpha, with cosmic time requires high precision measurements at individual redshi…
Most precise single redshift bound to Delta alpha/alpha
S. A. Levshakov, M. Centurion, P. Molaro +4
Verification of theoretical predictions of an oscillating behavior of the fine-structure constant alpha with cosmic time requires high precision Delta alpha/alpha measurements at i…
Spectral shape of the UV ionizing background and OVI absorbers at z ~ 1.5 towards HS0747+4259
D. Reimers, I. I. Agafonova, S. A. Levshakov +5
We report on high resolution spectra of the bright QSO HS0747+4259 (zem = 1.90, V = 15.8) observed to search for intermediate redshift OVI absorption systems. The spectra were obta…
Nitrogen-deficient and iron-rich associated absorbers with oversolar metallicities towards the quasar HE0141-3932
S. A. Levshakov, I. I. Agafonova, D. Reimers +3
HE0141-3932 (zem=1.80) is a bright blue radio-quite quasar which reveals an emission line spectrum with an unusually weak Ly-alpha line. In addition, large redshift differences (De…
Spectral energy distribution of the metagalactic ionizing radiation field from QSO absorption spectra
I. I. Agafonova, M. Centurion, S. A. Levshakov +1
A computational procedure is presented to estimate the spectral shape of the ionizing background between 1 and 10 Ryd by analyzing optically thin absorption systems in the spectra…
VLT/UVES shows no cosmological variability of alpha
P. Molaro, M. Centurion, S. D'Odorico +1
The cosmological variability of alpha is probed from individual observations of pairs of FeII lines. This procedure allows a better control of the systematics and avoids the influe…