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ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Infrared Excess of UV-Selected z = 2–10 Galaxies as a Function of UV-Continuum Slope and Stellar Mass

Bouwens, Rychard J. and Walter, Fabian (2016) ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Infrared Excess of UV-Selected z = 2–10 Galaxies as a Function of UV-Continuum Slope and Stellar Mass. Astrophysical Journal, 833 (1). Art. No. 72. ISSN 0004-637X.

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We make use of deep 1.2 mm continuum observations (12.7 μJy beam^(−1) rms) of a 1 arcmin^2 region in the Hubble Ultra Deep Field to probe dust-enshrouded star formation from 330 Lyman-break galaxies spanning the redshift range z = 2–10 (to ~2–3 M ⊙ yr^(−1) at 1σ over the entire range). Given the depth and area of ASPECS, we would expect to tentatively detect 35 galaxies, extrapolating the Meurer z ~ 0 IRX–β relation to z ≥ 2 (assuming dust temperature T_d ~ 35 K). However, only six tentative detections are found at z ≳ 2 in ASPECS, with just three at >3σ. Subdividing our z = 2–10 galaxy samples according to stellar mass, UV luminosity, and UV-continuum slope and stacking the results, we find a significant detection only in the most massive (>10^(9.75) M⊙) subsample, with an infrared excess (IRX = L_(IR)/L_(UV)) consistent with previous z ~ 2 results. However, the infrared excess we measure from our large selection of sub-L∗ (<10^(9.75) M⊙) galaxies is 0.11^(+0.32)_(-0.42) ± 0.34 (bootstrap and formal uncertainties) and 0.14^(+0.15)_(-0.14) ± 0.18 at z = 2–3 and z = 4–10, respectively, lying below even an IRX–β relation for the Small Magellanic Cloud (95% confidence). These results demonstrate the relevance of stellar mass for predicting the IR luminosity of z ≳ 2 galaxies. We find that the evolution of the IRX–stellar mass relationship depends on the evolution of the dust temperature. If the dust temperature increases monotonically with redshift (∝(1 + z)^(0.32)) such that T_d ~ 44–50 K at z ≥ 4, current results are suggestive of little evolution in this relationship to z ~ 6. We use these results to revisit recent estimates of the z ≥ 3 star formation rate density.

Item Type:Article
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URLURL TypeDescription Paper
Walter, Fabian0000-0003-4793-7880
Additional Information:© 2016 The American Astronomical Society. Received 2016 May 6; revised 2016 July 22; accepted 2016 August 3; published 2016 December 8. We thank an especially knowledgeable referee for their feedback, which greatly improved our paper. R.J.B. acknowledges enlightening discussions with Corentin Schreiber while writing this paper. F.W., I.R.S., and R.J.I. acknowledge support through ERC grants COSMICDAWN, DUSTYGAL, and COSMICISM, respectively. M.A. acknowledges partial support from FONDECYT through grant 1140099. I.R.S. also acknowledges support from STFC (ST/L00075X/1) and a Royal Society/Wolfson Merit award. Support for R.D. and B.M. was provided by the DFG priority program 1573 The physics of the interstellar medium. A.K. and F.B. acknowledge support by the Collaborative Research Council 956, sub-project A1, funded by the Deutsche Forschungsgemeinschaft (DFG). F.E.B., L.I., and J.G.-L. acknowledge support from CONICYT-Chile grants Basal-CATA PFB-06/2007. F.E.B. and J.G.-L. acknowledges support from FONDECYT Regular 1141218. F.E.B. also acknowledges support from "EMBIGGEN" Anillo ACT1101 and the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. L.I. acknowledges Conicyt grants Anilo ACT1417. D.R. acknowledges support from the National Science Foundation under grant number AST-1614213 to Cornell University. This paper makes use of the ALMA data from the program 2013.1.00718.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.
Funding AgencyGrant Number
European Research Council (ERC)UNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1140099
Science and Technology Facilities Council (STFC)ST/L00075X/1
Deutsche Forschungsgemeinschaft (DFG)1573
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)Anillo ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT1417
Subject Keywords:galaxies: evolution – galaxies: ISM – galaxies: star formation – galaxies: statistics – instrumentation: interferometers – submillimeter: galaxies
Record Number:CaltechAUTHORS:20161212-152729280
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Official Citation:Rychard J. Bouwens et al 2016 ApJ 833 72
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72733
Deposited By: Tony Diaz
Deposited On:12 Dec 2016 23:49
Last Modified:20 Aug 2017 05:43

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