Journal
ASTRONOMY & ASTROPHYSICS
Volume 643, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202038163
Keywords
galaxies: high-redshift; galaxies: ISM; dust; extinction
Categories
Funding
- ESO Telescopes at the La Silla Paranal Observatory under ESO programme [179.A-2005]
- Swiss National Science Foundation through the SNSF Professorship [157567]
- ERC [695671]
- Science and Technology Facilities Council (STFC)
- National Science Foundation [AST-1614213]
- Alexander von Humboldt Foundation through a Humboldt Research Fellowship for Experienced Researchers
- MIUR PRIN
- European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant [746119]
- Cosmic Dawn Center of Excellence - Danish National Research Foundation [140]
- FONDECYT Regular Grant [1202007]
- STFC [ST/M001172/1] Funding Source: UKRI
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We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of similar to 4.4-5.8. Our analyses are based on the far infrared continuum observations of 118 galaxies at rest-frame 158 mu m 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 (beta), stellar mass (M-star), and infrared excess (IRX = L-IR/L-UV). Twenty-three galaxies are individually detected in the continuum at > 3.5 sigma significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at z similar to 4.4-5.8. The individual detections and stacks show that the IRX-beta relation at z similar to 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-beta 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-star relations at z less than or similar to 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 greater than or similar to 4 are characterised by (i) a steeper attenuation curve than at z less than or similar to 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-star/M-circle dot> 10) at z similar to 5-6 already exhibit an obscured fraction of star formation of similar to 45%, indicating a rapid build-up of dust during the epoch of reionization.
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