Lyman break and ultraviolet-selected galaxies at z similar to 1-II. PACS 100 mu m/160 mu m FIR detections

I. Oteo, G. Magdis, A. Bongiovanni, A. M. Perez-Garcia, J. Cepa, B. Cedres, A. Ederoclite, M. Sanchez-Portal, J. A. L. Aguerri, E. J. Alfaro, B. Altieri, P. Andreani, T. Aparicio-Villegas, H. Aussel, N. Benitez, S. Berta, T. Broadhurst, J. Cabrera-Cano, F. J. Castander, M. CervinoA. Cimatti, D. Cristobal-Hornillos, E. Daddi, D. Elbaz, A. Fernandez-Soto, N. Foerster Schreiber, R. Genzel, R. M. Gonzalez-Delgado, C. Husillos, L. Infante, E. Le Floc'h, D. Lutz, B. Magnelli, R. Maiolino, I. Marquez, V. J. Martinez, J. Masegosa, I. Matute, M. Moles, A. Molino, A. del Olmo, J. Perea, R. Perez-Martinez, I. Pintos-Castro, A. Poglitsch, J. Polednikova, P. Popesso, M. Povic, F. Pozzi, F. Prada, J. M. Quintana, L. Riguccini, E. Sturm, L. Tacconi, I. Valtchanov, K. Viironen

Research output: Contribution to journalArticlepeer-review


In this work, we report the Photodetector Array Camera and Spectrometer (PACS) 100 mu m/160 mu m detections of a sample of 42 GALEX-selected and far-infrared (FIR)-detected Lyman break galaxies (LBGs) at z similar to 1 located in the Cosmic Evolution Survey (COSMOS) field and analyse their ultraviolet (UV) to FIR properties. The detection of these LBGs in the FIR indicates that they have a dust content high enough so that its emission can be directly detected. According to a spectral energy distribution (SED) fitting with stellar population templates to their UV-to-near-IR observed photometry, PACS-detected LBGs tend to be bigger (R-eff similar to 4.1 kpc), more massive [log (M-*/M-circle dot) similar to 10.7], dustier [E-s(B - V) similar to 0.40], redder in the UV continuum (beta similar to -0.60) and UV-brighter [log (L-UV/L-circle dot) similar to 10.1] than PACS-undetected LBGs. PACS-detected LBGs at z similar to 1 are mostly disc-like galaxies and are located over the green valley and red sequence of the colour-magnitude diagram of galaxies at their redshift. By using their UV and IR emission, we find that PACS-detected LBGs tend to be less dusty and have slightly higher total star formation rates (SFRs) than other PACS-detected UV-selected galaxies within the same redshift range. As a consequence of the selection effect due to the depth of the FIR observations employed, all our PACS-detected LBGs have total IR luminosities, L-IR, higher than 10(11) L-circle dot and thus are luminous IR galaxies. However, none of the PACS-detected LBGs are in the ultra-luminous IR galaxy (ULIRG) regime, L-IR >= 10(12) L-circle dot, where the FIR observations are complete. The finding of ULIRGs-LBGs at higher redshifts (z similar to 3) suggests an evolution of the FIR emission of LBGs with cosmic time. In an IRX-beta diagram, PACS-detected LBGs at z similar to 1 tend to be located around the relation for local starburst similarly to other UV-selected PACS-detected galaxies at the same redshift. Consequently, the dust-correction factors obtained with their UV continuum slope allow us to determine their total SFR, unlike at higher redshifts. However, the dust attenuation derived from UV to NIR SED fitting overestimates the total SFR for most of our PACS-detected LBGs in an age-dependent way: the overestimation factor is higher in younger galaxies. This is likely due to the typical degeneracy between dust attenuation and age in the SED fitting with synthetic templates and highlights the importance of the FIR measurements in the analysis of star-forming galaxies at intermediate redshifts.

Original languageEnglish
Pages (from-to)158-186
Number of pages29
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - Oct 2013


  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: star formation
  • infrared: galaxies
  • radio continuum: galaxies
  • ultraviolet: galaxies

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