Open AccessH i kinematics in a massive spiral galaxy at z = 0.89
Author(s) -
Koopmans L. V. E.,
De Bruyn A. G.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2005.00030.x
Subject(s) - physics , astrophysics , spiral galaxy , galaxy , redshift , radio telescope , advanced camera for surveys , einstein ring , hydrogen line , radius , star formation , spiral (railway) , astronomy , gravitational lens , mathematical analysis , computer security , mathematics , computer science
We present a kinematic model of the neutral hydrogen in the spiral galaxy of the lens system PKS 1830−211, based on a Multi‐Element Radio‐Linked Interferometer Network (MERLIN) 1.4‐GHz radio map and the integrated and redshifted 21‐cm hydrogen absorption‐line profile as measured with the Westerbork Synthesis Radio Telescope (WSRT). Degeneracies in the models do not allow a unique determination of the kinematic centre, and forthcoming deeper Hubble Space Telescope observations with the Advanced Camera for Surveys (ACS) are required to break this degeneracy. Even so, we measure the inclination of the hydrogen disc: i = 17°–32° , indicating a close to face‐on spiral galaxy. The optical depth increases with radius over the extent of the Einstein ring, suggesting H i depletion towards the lens centre. The latter could be due to star formation or conversion of H i into molecular hydrogen because of a higher metalicity/dust content in the galaxy centre. The neutral hydrogen optical depth gives N H I = 2 × 10 21 cm −2 at r = 5.0 h −1 70 kpc in the disc ( T s = 100 K) , comparable to local spiral galaxies.