Radio counterpart of the lensed sub-mm emission in the cluster MS0451.6-0305: new evidence for the merger scenario

A&A 509 (2010) 54

DOI: 10.1051/0004-6361/200912903 (http) or 10.1051/0004-6361/200912903 (doi)
ADS bibcode 2010A&A...509A..54B
arXiv:0910.1213

A. Berciano Alba [1,2], L.V.E. Koopmans [2], M.A. Garrett [1], O. Wucknitz [3], M. Limousin [4,5]

  1. ASTRON, Dwingeloo, The Netherlands
  2. Kapteyn Institute, Groningen, The Netherlands
  3. Argelander-Institut für Astronomie, Bonn, Germany
  4. Laboratoire d'Astrophysique de Marseille, France
  5. DARK, Copenhagen, Denmark

Abstract

SMM J04542-0301 is an extended (~1 arcmin) sub-mm source located near the core of the cluster MS0451.6-0305. It has been suggested that part of its emission arises from the interaction between a LBG and two EROs at z~2.9 that are multiply-imaged. However, the dramatic resolution difference between the sub-mm map and the optical/NIR images make it difficult to confirm this hypothesis. In this paper, we present a deep (~ 10 microJy/beam), high resolution (~2 arcsec) 1.4 GHz radio map of the cluster core, in which we have identified 6 sources located within SMM J04542-0301. The strong lensing effect in the radio data has been quantified by constructing a new lens model of the cluster. The brightest and most extended of these sources (RJ) is located in the middle of the sub-mm emission, and has no obvious counterpart in the optical/NIR. Three other detections (E1, E2 and E3) seem to be associated with the images of one of the EROs. The last two detections (CR1 and CR2), for which no optical/NIR counterpart have been found, seem to constitute two relatively compact emitting regions embedded in a ~5 arcsec extended radio source located at the position of the sub-mm peak. The presence of this extended component can only be explained if it is being produced by a lensed region of dust obscured star formation in the center of the merger. A comparison between the radio and sub-mm data at the same resolution suggests that E1, E2, E3, CR1 and CR2 are associated with the sub-mm emission. The radio observations provide strong observational evidence in favor of the merger hypothesis. However, the question if RJ is also contributing to the observed sub-mm emission remains open. These results illustrate the promising prospects for radio interferometry and strong gravitational lensing to study the internal structure of SMGs.

Key words: gravitational lensing - galaxies: starburst - radio continuum: galaxies - galaxies: clusters: individual: MS0451.6-0305


A&A 509 (2010) 54 (link to online journal)
DOI (Digital Object Identifier): 10.1051/0004-6361/200912903 (http) or 10.1051/0004-6361/200912903 (doi)
ADS bibcode 2010A&A...509A..54B (link to ADS entry)
Preprint version with reduced resolution images (19 pages): arXiv:0910.1213 (link to e-print archive)


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