The ALPINE-ALMA [CII] survey: Dust attenuation properties and obscured star formation at z ∼4.4-5.8

Y. Fudamoto, P. A. Oesch, A. Faisst, M. Béthermin, M. Ginolfi, Y. Khusanova, F. Loiacono, O. Le Fèvre, P. Capak, D. Schaerer, J. D. Silverman, P. Cassata, L. Yan, R. Amorin, S. Bardelli, M. Boquien, A. Cimatti, M. Dessauges-Zavadsky, S. Fujimoto, C. GruppioniN. P. Hathi, E. Ibar, G. C. Jones, A. M. Koekemoer, G. Lagache, B. C. Lemaux, R. Maiolino, D. Narayanan, F. Pozzi, D. A. Riechers, G. Rodighiero, M. Talia, S. Toft, L. Vallini, D. Vergani, G. Zamorani, E. Zucca

Research output: Contribution to journalReview articlepeer-review

4 Citations (Scopus)

Abstract

We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of ∼4.4 - 5.8. Our analyses are based on the far infrared continuum observations of 118 galaxies at rest-frame 158 μm obtained with the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE). We study the connection between the ultraviolet (UV) spectral slope (β), stellar mass (M∗), and infrared excess (IRX = LIR/LUV). Twenty-three galaxies are individually detected in the continuum at > 3.5σ significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at z ∼ 4.4 - 5.8. The individual detections and stacks show that the IRX-β relation at z ∼ 5 is consistent with a steeper dust attenuation curve than typically found at lower redshifts (z < 4). The attenuation curve is similar to or even steeper than that of the extinction curve of the Small Magellanic Cloud. This systematic change of the IRX-β relation as a function of redshift suggests an evolution of dust attenuation properties at z > 4. Similarly, we find that our galaxies have lower IRX values, up to 1 dex on average, at a fixed mass compared to previously studied IRX-M∗ relations at z 4, albeit with significant scatter. This implies a lower obscured fraction of star formation than at lower redshifts. Our results suggest that dust properties of UV-selected star forming galaxies at z 4 are characterised by (i) a steeper attenuation curve than at z 4, and (ii) a rapidly decreasing dust obscured fraction of star formation as a function of redshift. Nevertheless, even among this UV-selected sample, massive galaxies (log M∗/M· > 10) at z ∼ 5 - 6 already exhibit an obscured fraction of star formation of ∼45%, indicating a rapid build-up of dust during the epoch of reionization.

Original languageEnglish
Article numberA4
JournalAstronomy and Astrophysics
Volume643
DOIs
Publication statusPublished - 2020 Nov 1
Externally publishedYes

Keywords

  • Dust
  • Extinction
  • Galaxies: ISM
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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