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

Yoshinobu Fudamoto, P. A. Oesch, A. Faisst, M. Bethermin, M. Ginolfi, Y. Khusanova, F. Loiacono, O. Le Fèvre, P. Capak, D. Schaerer, J. 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 journalArticlepeer-review

Abstract

We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at redshift ∼ 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 ALMA large program ALPINE. We study the connection between the UV spectral slope (β), stellar mass (M?), and infrared excess (IRX= LIR/LUV). Twenty-three galaxies are individually detected in the continuum at > 3.5 σ significance. We perform a stacking analysis using both detections and non-detections 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 (SMC). 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 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
JournalUnknown Journal
Publication statusPublished - 2020 Apr 22
Externally publishedYes

Keywords

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

ASJC Scopus subject areas

  • General

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