112 citations · 778 across the 22 of their papers we have counts for
10 papers · 1 filter
A new approach for testing variations of fundamental constants over cosmic epochs using FIR fine-structure lines
S. A. Levshakov, D. Reimers, M. G. Kozlov +2
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 ba…
HE 0515-4414 - an unusual sub-damped Ly alpha system revisited
R. Quast, D. Reimers, R. Baade
Using STIS and VLT UVES observations we have examined the ionization, abundances, and differential dust depletion of metals, the kinematic structure, and the physical conditions in…
Spectral shape of the UV ionizing background and HeII absorption at redshifts 1.8 < z < 2.9
I. I. Agafonova, S. A. Levshakov, D. Reimers +4
The shape of the UV ionizing background is reconstructed from optically thin metal absorption-line systems identified in spectra of HE2347-4342, Q1157+3143, and HS1700+6416 in the…
Fluctuations of the intergalactic UV background towards two lines of sight
C. Fechner, D. Reimers
We present a reanalysis of the HeII Lyman alpha absorption towards the quasars HS1700+6416 and HE2347-4342 using new high S/N, optical observations. An alternative analysis method…
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…
Intergalactic HeII absorption towards QSO 1157+3143
D. Reimers, C. Fechner, H. -J. Hagen +3
We report the discovery of a further line of sight allowing detection of HeII Ly alpha absorption by the intergalactic medium. A HST/STIS survey of 32 bright z ~ 3 quasars selected…