Modeling of the HerMES submillimeter source lensed by a dark matter dominated foreground group of galaxies

R. Gavazzi, A. Cooray, A. Conley, J. E. Aguirre, A. Amblard, R. Auld, A. Beelen, A. Blain, R. Blundell, J. Bock, C. M. Bradford, C. Bridge, D. Brisbin, D. Burgarella, P. Chanial, E. Chapin, N. Christopher, D. L. Clements, P. Cox, S. G. DjorgovskiC. D. Dowell, S. Eales, L. Earle, T. P. Ellsworth-Bowers, D. Farrah, A. Franceschini, H. Fu, J. Glenn, E. A. Gonzalez Solares, M. Griffin, M. A. Gurwell, M. Halpern, E. Ibar, R. J. Ivison, M. Jarvis, J. Kamenetzky, S. Kim, M. Krips, L. Levenson, R. Lupu, A. Mahabal, P. D. Maloney, C. Maraston, L. Marchetti, G. Marsden, H. Matsuhara, A. M. J. Mortier, E. Murphy, B. J. Naylor, R. Neri, H. T. Nguyen, S. J. Oliver, A. Omont, M. J. Page, A. Papageorgiou, C. P. Pearson, I. Perez-Fournon, M. Pohlen, N. Rangwala, J. I. Rawlings, G. Raymond, D. Riechers, G. Rodighiero, I. G. Roseboom, M. Rowan-Robinson, B. Schulz, Douglas Scott, K. S. Scott, P. Serra, N. Seymour, D. L. Shupe, A. J. Smith, M. Symeonidis, K. E. Tugwell, M. Vaccari, E. Valiante, I. Valtchanov, A. Verma, J. D. Vieira, L. Vigroux, L. Wang, J. Wardlow, D. Wiebe, G. Wright, C. K. Xu, G. Zeimann, M. Zemcov, J. Zmuidzinas

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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 = 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.
Original languageEnglish
Number of pages8
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 10 Sept 2011


  • galaxies: elliptical and lenticular, cD
  • galaxies: groups: general
  • galaxies: halos
  • gravitational lensing: strong
  • submillimeter: galaxies


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