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

Gavazzi, R. and Cooray, A. and Blain, A. and Bock, J. J. and Bradford, C. M. and Bridge, C. and Djorgovski, S. G. and Dowell, C. D. and Fu, H. and Levenson, L. and Mahabal, A. and Murphy, E. and Nguyen, H. T. and Riechers, D. and Schulz, B. and Shupe, D. L. and Vieira, J. D. and Xu, C. K. and Zemcov, M. and Zmuidzinas, J. (2011) Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies. Astrophysical Journal, 738 (2). Art. No. 125. ISSN 0004-637X.

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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) = 4".10 ± 0".02, 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) ≃ 4.5 kpc) ~ 47% within the effective radius of the main deflecting galaxy of stellar mass M_(*,G1) = [8.5 ± 1.6] × 10^(11) 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Cooray, A.0000-0002-3892-0190
Blain, A.0000-0001-7489-5167
Bock, J. J.0000-0002-5710-5212
Bradford, C. M.0000-0001-5261-7094
Djorgovski, S. G.0000-0002-0603-3087
Fu, H.0000-0001-9608-6395
Mahabal, A.0000-0003-2242-0244
Murphy, E.0000-0001-7089-7325
Riechers, D.0000-0001-9585-1462
Shupe, D. L.0000-0003-4401-0430
Xu, C. K.0000-0002-1588-6700
Zemcov, M.0000-0001-8253-1451
Additional Information:© 2011 The American Astronomical Society. Received 2011 February 9; accepted 2011 June 7; published 2011 August 18. Some of the data presented herein were obtained at the W. M. Keck Observatory which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. R.G. and A.O. acknowledge support from the Centre National de Etudes Spatiales. S.G.D. and A.A.M. acknowledge partial support from SN grant AST-0909182 and the Ajax Foundation. SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including University of Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, University of Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, University of Sussex (UK); Caltech, JPL, NHSC, University of Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC (UK); and NASA (USA). The IRAM Plateau de Bure Interferometer is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Funding AgencyGrant Number
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Ajax FoundationUNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
National Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Ministerio de Ciencia e Innovación (MCINN)UNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
Subject Keywords:galaxies: elliptical and lenticular, cD; galaxies: groups: general; galaxies: halos; gravitational lensing: strong; submillimeter: galaxies
Issue or Number:2
Classification Code:PACS: 95.35.+d; 98.65.Cw; 98.52.Eh; 98.62.Sb; 98.62.Py; 98.52.Lp
Record Number:CaltechAUTHORS:20111004-113055775
Persistent URL:
Official Citation:Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies R. Gavazzi et al. 2011 ApJ 738 125
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25634
Deposited By: Ruth Sustaita
Deposited On:04 Oct 2011 20:00
Last Modified:09 Mar 2020 13:18

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