A3COSMOS: the dust attenuation of star-forming galaxies at z = 2.5-4.0 from the COSMOS-ALMA archive
Abstract
We present an analysis of the dust attenuation of star-forming galaxies at z = 2.5-4.0 through the relationship between the UV spectral slope (β), stellar mass (M*), and the infrared excess (IRX = LIR/LUV) based on far-infrared continuum observations from the Atacama Large Millimeter/sub-millimeter Array (ALMA). Our study exploits the full ALMA archive over the COSMOS field processed by the A3COSMOS team, which includes an unprecedented sample of ∼1500 galaxies at z ∼ 3 as primary or secondary targets in ALMA band 6 or 7 observations with a median continuum sensitivity of 126 {μ Jy beam}^{-1} (1σ). The detection rate is highly mass dependent, decreasing drastically below log (M*/M⊙) = 10.5. The detected galaxies show that the IRX-β relationship of massive (log M*/M⊙ > 10) main-sequence galaxies at z = 2.5-4.0 is consistent with that of local galaxies, while starbursts are generally offset by ∼ 0.5 dex to larger IRX values. At the low-mass end, we derive upper limits on the infrared luminosities through stacking of the ALMA data. The combined IRX-M* relation at {log ({M}_{\ast }/M_{⊙ })> 9} exhibits a significantly steeper slope than reported in previous studies at similar redshifts, implying little dust obscuration at log M*/M⊙ < 10. However, our results are consistent with earlier measurements at z ∼ 5.5, indicating a potential redshift evolution between z ∼ 2 and z ∼ 6. Deeper observations targeting low-mass galaxies will be required to confirm this finding.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2020
- DOI:
- 10.1093/mnras/stz3248
- arXiv:
- arXiv:1910.12885
- Bibcode:
- 2020MNRAS.491.4724F
- Keywords:
-
- galaxies: evolution;
- galaxies: ISM;
- galaxies: star formation;
- submillimetre: ISM;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 5 figures, MNRAS submitted