Measures of star formation rates from infrared (Herschel) and UV (GALEX) emissions of galaxies in the HerMES fields

V. Buat (1) , E. Giovannoli , D. Burgarella (1) , B. Altieri , A. Amblard , V. Arumugam , H. Aussel , T. Babbedge , A. Blain , J. Bock , A. Boselli (1) , N. Castro-Rodriguez , A. Cava , P. Chanial , D. L. Clements , A. Conley , L. Conversi , A. Cooray , C. D. Dowell , E. Dwek , S. Eales , D. Elbaz , M. Fox , A. Franceschini , W. Gear , J. Glenn , M. Griffin , M. Halpern , E. Hatziminaoglou , S. Heinis , E. Ibar , K. Isaak , R. J. Ivison , Guilaine Lagache , L. Levenson , C. J. Lonsdale , N. Lu , S. Madden , B. Maffei , G. Magdis , G. Mainetti , L. Marchetti , G. E. Morrison , H. T. Nguyen , B. O'Halloran , S. J. Oliver , A. Omont , F. N. Owen , M. J. Page , M. Pannella , P. Panuzzo , A. Papageorgiou , C. P. Pearson , I. Perez-Fournon , M. Pohlen , D. Rigopoulou , D. Rizzo , I. G. Roseboom , M. Rowan-Robinson , M. Sanchez Portal , B. Schulz , N. Seymour , D. L. Shupe , A. J. Smith , J. A. Stevens , V. Strazzullo , M. Symeonidis , M. Trichas , K. E. Tugwell , M. Vaccari , E. Valiante , I. Valtchanov , L. Vigroux , L. Wang , R. Ward , Gavin Wright , C. K. Xu , M. Zemcov

1 LAM - Laboratoire d'Astrophysique de Marseille

The reliability of infrared (IR) and ultraviolet (UV) emissions to measure star formation rates (SFRs) in galaxies is investigated for a large sample of galaxies observed with the Spectral and Photometric Imaging Receiver (SPIRE) and the Photodetector ArrayCamera and Spectrometer (PACS) instruments on Herschel as part of the Herschel Multi-Tiered Extragalactic Survey (HerMES) project. We build flux-limited 250-mu m samples of sources at redshift z \textless 1, cross-matched with the Spitzer/MIPS and GALEX catalogues. About 60 per cent of the Herschel sources are detected in UV. The total IR luminosities, L-IR, of the sources are estimated using a spectral energy distribution (SED) fitting code that fits to fluxes between 24 and 500 mu m. Dust attenuation is discussed on the basis of commonly used diagnostics: the L-IR/L-UV ratio and the slope, beta, of the UV continuum. A mean dust attenuation A(UV) of similar or equal to 3 mag is measured in the samples. L-IR/L-UV is found to correlate with L-IR. Galaxies with L-IR \textgreater 10(11) L-circle dot and 0.5 \textless z \textless 1 exhibit a mean dust attenuation A(UV) of about 0.7 mag lower than that found for their local counterparts, although with a large dispersion. Our galaxy samples span a large range of beta and L-IR/L-UV values which, for the most part, are distributed between the ranges defined by the relations found locally for starburst and normal star-forming galaxies. As a consequence the recipe commonly applied to local starbursts is found to overestimate the dust attenuation correction in our galaxy sample by a factor of similar to 2-3. The SFRs deduced from L-IR are found to account for about 90 per cent of the total SFR; this percentage drops to 71 per cent for galaxies with SFR \textless 1M(circle dot) yr(-1) (or L-IR \textless 10(10) L-circle dot). For these faint objects, one needs to combine UV and IR emissions to obtain an accurate measure of the SFR.

Domaines: Astrophysique [astro-ph]

V. Buat, E. Giovannoli, D. Burgarella, B. Altieri, A. Amblard, et al.. Measures of star formation rates from infrared (Herschel) and UV (GALEX) emissions of galaxies in the HerMES fields. Monthly Notices of the Royal Astronomical Society, 2010, 409 (1), pp.L1--L6. ⟨10.1111/j.1745-3933.2010.00916.x⟩. ⟨hal-01434473⟩