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Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies

Gavazzi, R; Cooray, A; Conley, A; Aguirre, JE; Amblard, A; Auld, R; Beelen, A; ... Zmuidzinas, J; + view all (2011) Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies. The Astrophysical Journal , 738 (2) , Article 125. 10.1088/0004-637X/738/2/125. Green open access

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Abstract

We present the results of a gravitational lensing analysis of the bright z s = 2.957 submillimeter galaxy (SMG) HERMES found in the Herschel/SPIRE science demonstration phase data from the Herschel Multi-tiered Extragalactic Survey (HerMES) project. The high-resolution imaging available in optical and near-IR channels, along with CO emission obtained with the Plateau de Bure Interferometer, allows us to precisely estimate the intrinsic source extension and hence estimate the total lensing magnification to be μ = 10.9 ± 0.7. We measure the half-light radius R eff of the source in the rest-frame near-UV and V bands that characterize the unobscured light coming from stars and find R eff, * = [2.0 ± 0.1] kpc, in good agreement with recent studies on the SMG population. This lens model is also used to estimate the size of the gas distribution (R eff, gas = [1.1 ± 0.5] kpc) by mapping back in the source plane the CO (J = 5 → 4) transition line emission. The lens modeling yields a relatively large Einstein radius R Ein = 4farcs10 ± 0farcs02, corresponding to a deflector velocity dispersion of [483 ± 16] km s–1. This shows that HERMES is lensed by a galaxy group-size dark matter halo at redshift z l ~ 0.6. The projected dark matter contribution largely dominates the mass budget within the Einstein radius with f dm(< R Ein) ~ 80%. This fraction reduces to f dm(< R eff, G1 sime 4.5 kpc) ~ 47% within the effective radius of the main deflecting galaxy of stellar mass M *, G1 = [8.5 ± 1.6] × 1011 M ☉. At this smaller scale the dark matter fraction is consistent with results already found for massive lensing ellipticals at z ~ 0.2 from the Sloan Lens ACS Survey.

Type: Article
Title: Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/0004-637X/738/2/125
Publisher version: http://dx.doi.org/10.1088/0004-637X/738/2/125
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, galaxies: elliptical and lenticular, cD, galaxies: groups: general, galaxies: halos, gravitational lensing: strong, submillimeter: galaxies, HIGH-DENSITY ENVIRONMENTS, ELLIPTIC GALAXIES, HIGH-REDSHIFT, ACS SURVEY, STAR-FORMATION, NUMBER COUNTS, MASS PROFILE, HALOS, FIELD, EVOLUTION
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/1372062
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