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 (1) , P. Chanial , E. Chapin , N. Christopher , D. L. Clements , P. Cox , S. G. Djorgovski , C. 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 , Gavin Wright , C. K. Xu , G. Zeimann , M. Zemcov , J. Zmuidzinas

1 LAM - Laboratoire d'Astrophysique de Marseille

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 mu = 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,R-* = [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,R-gas = [1.1 +/- 0.5] kpc) by mapping back in the source plane the CO (J = 5 -\textgreater 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) similar to 0.6. The projected dark matter contribution largely dominates the mass budget within the Einstein radius with f(dm)(\textlessR-Ein) similar to 80%. This fraction reduces to f(dm)(\textless R-eff,R-G1 similar or equal to 4.5 kpc) similar to 47% within the effective radius of the main deflecting galaxy of stellar mass M-*,M-G1 = [8.5 +/- 1.6] x 10(11) M-circle dot. At this smaller scale the dark matter fraction is consistent with results already found for massive lensing ellipticals at z similar to 0.2 from the Sloan Lens ACS Survey.

Domaines: Astrophysique [astro-ph]

R. Gavazzi, A. Cooray, A. Conley, J. E. Aguirre, A. Amblard, et al.. MODELING OF THE HERMES SUBMILLIMETER SOURCE LENSED BY A DARK MATTER DOMINATED FOREGROUND GROUP OF GALAXIES. The Astrophysical Journal, 2011, 738 (2), ⟨10.1088/0004-637X/738/2/125⟩. ⟨hal-01438061⟩