Open AccessSpectroscopy of the optical Einstein ring 0047 – 2808
Author(s) -
S. J. Warren,
A. Iovino,
Paul C. Hewett,
P. A. Shaver
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01881.x
Subject(s) - physics , astrophysics , galaxy , velocity dispersion , redshift , radius , line (geometry) , radial velocity , astronomy , stars , geometry , computer security , mathematics , computer science
We present optical and near‐infrared spectroscopic observations of the optical Einstein ring 0047 – 2808. We detect both [O III ] lines λλ4959, 5007 near ∼ 2.3 μm, confirming the redshift of the lensed source as z = 3.595. The Lyα line is redshifted relative to the [O III ] line by 140 ± 20 km s −1 . Similar velocity shifts have been seen in nearby starburst galaxies. The [O III ] line is very narrow, 130 km s −1 FWHM. If the ring is the image of the centre of a galaxy, the one‐dimensional stellar velocity dispersion σ = 55 km s −1 is considerably smaller than the value predicted by Baugh et al. for the somewhat brighter Lyman‐break galaxies. The Lyα line is significantly broader than the [O III ] line, probably due to resonant scattering. The stellar central velocity dispersion of the early‐type deflector galaxy at z = 0.485 is 250 ± 30 km s −1 . This value is in good agreement both with the value predicted from the radius of the Einstein ring (and a singular isothermal sphere model for the deflector), and with the value estimated from the D n −σ relation.