The ultraviolet to far-infrared spectral energy distribution of star-forming galaxies in the redshift desert

I. Oteo*, A. Bongiovanni, G. Magdis, A. M. Perez-Garcia, J. Cepa, H. Dominguez Sanchez, A. Ederoclite, M. Sanchez-Portal, I. Pintos-Castro

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We analyse the rest-frame ultraviolet (UV) to near-infrared (near-IR) spectral energy distribution (SED) of Lyman-break galaxies (LBGs), star-forming (SF) BzK (sBzK) and UV-selected galaxies at 1.5 less than or similar to z less than or similar to 2.5 in the COSMOS, GOODS-N and GOODS-S fields. Additionally, we complement the multiwavelength coverage of the galaxies located in the GOODS fields with deep far-infrared (FIR) data taken from the GOODS-Herschel project. According to their best-fitting SED-derived properties we find that, because of their selection criterion involving UV measurements, LBGs tend to be UV-brighter and bluer and have a less prominent Balmer break (i.e. are younger) and higher dust-corrected total star-formation rate (SFR) than sBzK galaxies. In this way, sBzK galaxies represent the general population of SF galaxies at z similar to 2 better than LBGs. In a colour-mass diagram, LBGs at z similar to 2 are mostly located over the blue cloud, although galaxies with higher age, higher dust attenuation and redder UV continuum slope deviate to the green valley and red sequence. Furthermore, for a given stellar mass, LBGs tend to have bluer optical colours than sBzK and UV-selected galaxies. We find clean Photodetector Array Camera and Spectrometer (PACS: 100- or 160-mu m) individual detections for a subsample of 48 LBGs, 89 sBzK and 91 UV-selected galaxies that measure their dust emission directly. Their SFRtotal = SFRUV + SFRIR cannot be recovered with the dust-correction factors derived from their continuum slope and the infrared excess (IRX)-beta relations for local starbursts, similar to what happens at higher redshifts. This might have implications, for example, in the definition of the main sequence (MS) at z similar to 2, which is sensitive to the dust-correction factors adopted. In an SFR-mass diagram, PACS-detected galaxies are located above the Daddi et al. MS and thus their star formation is probably driven by starbursts. This is in agreement with the shape of their IR SEDs. PACS-detected galaxies with redder UV continuum slope and higher stellar mass are more attenuated. We find that, for a given UV continuum slope, the dustiest galaxies at higher redshifts are more attenuated and that for a given stellar mass the dustiest galaxies at higher redshifts have stronger FIR emission. This suggests an evolution of their dust properties. However, we do not find significant evolution in the relation between dust attenuation and stellar mass with redshift, at least at z <2.5. There is a subpopulation of 17, 26 and 27 LBGs, sBzK and UV-selected galaxies, respectively, that are detected in any of the Spectral and Photometric Imaging REceiver (SPIRE: 250-, 350- and 500-mu m) bands. We speculate that this sample of SPIRE-detected LBGs is the bridging population between submillimetre galaxies and LBGs.

Original languageEnglish
Pages (from-to)1337-1363
Number of pages27
JournalMonthly Notices of the Royal Astronomical Society
Volume439
Issue number2
DOIs
Publication statusPublished - Apr 2014

Keywords

  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: star formation
  • infrared: galaxies
  • ultraviolet: galaxies
  • LYMAN-BREAK GALAXIES
  • DEEP FIELD-SOUTH
  • SIMILAR-TO 3
  • UV-SELECTED GALAXIES
  • RELEASE SCIENCE OBSERVATIONS
  • DUST ATTENUATION PROPERTIES
  • FORMATION RATE DENSITY
  • STELLAR MASS DENSITY
  • DIGITAL SKY SURVEY
  • LY-ALPHA EMITTERS

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