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Published February 21, 2013 | Published
Journal Article Open

HERMES: unveiling obscured star formation – the far-infrared luminosity function of ultraviolet-selected galaxies at z ∼ 1.5


We study the far-infrared and sub-millimetre properties of a sample of ultraviolet (UV) selected galaxies at z ∼ 1.5. Using stacking at 250, 350 and 500 μm from Herschel Space Observatory Spectral and Photometric Imaging Receiver (SPIRE) imaging of the Cosmological Evolution Survey (COSMOS) field obtained within the Herschel Multi-tiered Extragalactic Survey (HERMES) key programme, we derive the mean infrared (IR) luminosity as a function of both UV luminosity and slope of the UV continuum β. The IR to UV luminosity ratio is roughly constant over most of the UV luminosity range we explore. We also find that the IR to UV luminosity ratio is correlated with β. We observe a correlation that underestimates the correlation derived from low-redshift starburst galaxies, but is in good agreement with the correlation derived from local normal star-forming galaxies. Using these results we reconstruct the IR luminosity function of our UV-selected sample. This luminosity function recovers the IR luminosity functions measured from IR-selected samples at the faintest luminosities (L_(IR) ∼ 10^(11) L_⊙), but might underestimate them at the bright-end (L_(IR) ≳ 5 × 10^(11) L_⊙). For galaxies with 10^(11) < L_(IR)/L_⊙ < 10^(13), the IR luminosity function of an UV selection recovers (given the differences in IR-based estimates) 52–65 to 89–112 per cent of the star formation rate density derived from an IR selection. The cosmic star formation rate density derived from this IR luminosity function is 61–76 to 100–133 per cent of the density derived from IR selections at the same epoch. Assuming the latest Herschel results and conservative stacking measurements, we use a toy model to fully reproduce the far-IR luminosity function from our UV selection at z ∼ 1.5. This suggests that a sample around 4 mag deeper (i.e. reaching u^* ∼ 30 mag) and a large dispersion of the IR to UV luminosity ratio are required.

Additional Information

© 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2012 November 12. Received 2012 October 31; in original form 2012 April 5. First published online: December 13, 2012. We thank the referee for a careful reading and detailed, constructive comments which helped improving the paper. SH and VB thank the French Space Agency (CNES) for financial support. SPIRE has been developed by a consortium of institutes led by Cardiff Univ. (UK) and including: Univ. Lethbridge (Canada); NAOC (China); CEA,LAM(France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). We thank the COSMOS collaboration for sharing data used in this paper. The data presented in this paper will be released through the Herschel Database in Marseille (HeDaM, http://hedam. oamp.fr/HerMES), operated by CeSAM and hosted by the Laboratoire d'Astrophysique de Marseille.

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Published - MNRAS-2013-Heinis-1113-32.pdf


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