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Multi-wavelength properties of Spitzer selected starbursts at z ~ 2

Fiolet, N. and Omont, A. and Polletta, M. and Owen, F. and Berta, S. and Shupe, D. and Siana, B. and Lonsdale, C. and Strazzullo, V. and Pannella, M. and Baker, A. J. and Beelen, A. and Biggs, A. and de Breuck, C. and Farrah, D. and Ivison, R. and Lagache, G. and Lutz, D. and Tacconi, L. J. and Zylka, R. (2009) Multi-wavelength properties of Spitzer selected starbursts at z ~ 2. Astronomy and Astrophysics, 508 (1). pp. 117-132. ISSN 0004-6361.

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Context. Wide-field Spitzer surveys allow identification of thousands of potentially high-z submillimeter galaxies (SMGs) through their bright 24 μm emission and their mid-IR colors. Aims. We want to determine the average properties of such z ~ 2 Spitzer-selected SMGs by combining millimeter, radio, and infrared photometry for a representative IR-flux (λ_(rest) ~ 8 μm) limited sample of SMG candidates. Methods. A complete sample of 33 sources believed to be starbursts (“5.8 μm-peakers”) was selected in the (0.5 deg^2) J1046+56 field with selection criteria F_(24 μm) > 400 μJy, the presence of a redshifted stellar emission peak at 5.8 μm, and r'_(Vega) > 23. The field, part of the SWIRE Lockman Hole field, benefits from very deep VLA/GMRT 20 cm, 50 cm, and 90 cm radio data (all 33 sources are detected at 50 cm), and deep 160 μm and 70 μm Spitzer data. The 33 sources, with photometric redshifts ~1.5−2.5, were observed at 1.2mm with IRAM-30m/MAMBO to an rms ~0.7–0.8mJy in most cases. Their millimeter, radio, 7-band Spitzer, and near-IR properties were jointly analyzed. Results. The entire sample of 33 sources has an average 1.2mm flux density of 1.56 ± 0.22 mJy and a median of 1.61mJy, so the majority of the sources can be considered SMGs. Four sources have confirmed 4σ detections, and nine were tentatively detected at the 3σ level. Because of its 24 μm selection, our sample shows systematically lower F_(1.2mm)/F_(24 μm) flux ratios than classical SMGs, probably because of enhanced PAH emission. A median FIR SED was built by stacking images at the positions of 21 sources in the region of deepest Spitzer coverage. Its parameters are T_(dust) = 37 ± 8K, L_(FIR) = 2.5 × 10^(12) L_☉, and SFR = 450 M yr^(−1). The FIR-radio correlation provides another estimate of LFIR for each source, with an average value of 4.1 × 10^(12) L_☉; however, this value may be overestimated because of some AGN contribution. Most of our targets are also luminous star-forming BzK galaxies which constitute a significant fraction of weak SMGs at 1.7 ≲ z ≲ 2.3. Conclusions. Spitzer 24 μm-selected starbursts and AGN-dominated ULIRGs can be reliably distinguished using IRAC-24 μm SEDs. Such “5.8 μm-peakers” with F_(24 μm) > 400 μJy have L_(FIR) 10^(12) L_☉. They are thus z ~ 2 ULIRGs, and the majority may be considered SMGs. However, they have systematically lower 1.2mm/24 μm flux density ratios than classical SMGs, warmer dust, comparable or lower IR/mm luminosities, and higher stellar masses. About 2000−3000 “5.8 μm-peakers” may be easily identifiable within SWIRE catalogues over 49 deg^2.

Item Type:Article
Related URLs:
URLURL TypeDescription
Omont, A.0000-0002-4721-3922
Polletta, M.0000-0001-7411-5386
Berta, S.0000-0002-0320-1532
Shupe, D.0000-0003-4401-0430
Siana, B.0000-0002-4935-9511
Lonsdale, C.0000-0003-0898-406X
Baker, A. J.0000-0002-7892-396X
Biggs, A.0000-0002-1117-9961
de Breuck, C.0000-0002-6637-3315
Farrah, D.0000-0003-1748-2010
Ivison, R.0000-0001-5118-1313
Lagache, G.0000-0003-1492-2519
Lutz, D.0000-0003-0291-9582
Tacconi, L. J.0000-0002-1485-9401
Additional Information:© 2009 ESO. Received 22 June 2009; accepetd 1 September 2009. We thank Roy Kilgard, Jacqueline Bergeron, Attila Kovács and Helmut Dannerbauer for their helpful contribution. This work includes observations made with IRAM, which is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). Thanks to the staff of IRAM for their support and the anonymous observers of the MAMBO pool for observations presented here. This work is based in part on observations made within the context of SWIRE survey with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The VLA is operated by NRAO, the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The optical data come from KPNO (Kitt Peak National Observatory), National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. This work includes observations made with WFCAM/UKIRT. The UKIRT is operated by the Joint Astronomy Centre on behalf of the UK’s Science and Technology Facilities Council.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:galaxies: high-redshift; galaxies: starburst; galaxies: active; infrared: galaxies; submillimeter; radio continuum: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20100111-095352567
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Official Citation:Multi-wavelength properties of Spitzer selected starbursts at z ~ 2 N. Fiolet, A. Omont, M. Polletta, F. Owen, S. Berta, D. Shupe, B. Siana, C. Lonsdale, V. Strazzullo, M. Pannella, A. J. Baker, A. Beelen, A. Biggs, C. De Breuck, D. Farrah, R. Ivison, G. Lagache, D. Lutz, L. J. Tacconi and R. Zylka A&A 508 (1) 117-132 (2009) DOI: 10.1051/0004-6361/200912742
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17131
Deposited By: Jason Perez
Deposited On:11 Jan 2010 19:31
Last Modified:30 Sep 2020 17:56

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