Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 423, Issue 2, Pages 1073-1088Publisher
OXFORD UNIV PRESS
DOI: 10.1111/j.1365-2966.2012.20934.x
Keywords
gravitational lensing: strong; galaxies: fundamental parameters; galaxies: haloes; galaxies: kinematics and dynamics; galaxies: spiral; galaxies: structure
Categories
Funding
- Department of Energy [DE-AC02-76SF00515]
- CITA
- National Science Foundation Science and Technology Center CfAO
- NSF [AST 08-08133, NSF-0642621, PHY99-07949]
- HST [AR-10664.01-A, AR-10965.02-A, GO-11206.02-A]
- TABASGO
- Kavli foundations
- Royal Society
- Packard Foundation
- NWO-VIDI [639.042.505]
- NASA [GO-10587, GO-11202, GO-11978, NAS 5-26555]
- NASA/ESA Hubble Space Telescope and obtained at Space Telescope Science Institut
- W. M. Keck Foundation
- SDSS
- SDSS-II
- Alfred P. Sloan Foundation
- National Science Foundation
- US Department of Energy
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- STFC [ST/J001538/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/J001538/1, ST/H00243X/1] Funding Source: researchfish
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [808133] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [807458] Funding Source: National Science Foundation
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We construct a fully self-consistent mass model for the lens galaxy SDSS J2141 at redshift 0.14, and use it to improve on previous studies by modelling its gravitational lensing effect, gas rotation curve and stellar kinematics simultaneously. We adopt a very flexible axisymmetric mass model constituted by a generalized NavarroFrenkWhite (NFW) dark matter halo and a stellar mass distribution obtained by deprojecting the multi-Gaussian expansion fit to the high-resolution K'-band laser guide star adaptive optics imaging data of the galaxy, with the (spatially constant) mass-to-light ratio as a free parameter. We model the stellar kinematics by solving the anisotropic Jeans equations. We find that the inner logarithmic slope of the dark halo is weakly constrained, i.e. , and consistent with an unmodified NFW profile; we can conclude, however, that steep profiles (?= 1.5) are disfavoured (<14 per cent posterior probability). We marginalize over this parameter to infer the galaxy to have (i) a dark matter fraction within 2.2 disc radii of , independent of the galaxy stellar population, implying a maximal disc for SDSS J2141; (ii) an apparently uncontracted dark matter halo, with concentration and virial velocity , consistent with ? cold dark matter (?CDM) predictions; (iii) a slightly oblate halo (), consistent with predictions from baryon-affected models. Comparing the tightly constrained gravitational stellar mass inferred from the combined analysis () with that inferred from stellar population modelling of the galaxies colours, and accounting for an expected cold gas fraction of 20 +/- 10 per cent, we determine a preference for a Chabrier IMF over Salpeter IMF by a Bayes factor of 5.7 (corresponding to substantial evidence). We infer a value for the orbital anisotropy parameter in the meridional plane, in agreement with most studies of local disc galaxies, and ruling out at 99 per cent confidence level that the dynamics of this system can be described by a two-integral distribution function.
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