Work

An empirical derivation of the average dust attenuation law at 2<z<7

Year: 2026

Type: article

Abstract: Context. Dust attenuation significantly affects the observed spectral energy distributions (SEDs) of galaxies, introducing significant uncertainties in the derivation of key physical properties such as star formation rates, stellar masses, and metallicities. While attenuation curves have been extensively studied in the Local Universe and at intermediate redshift, direct spectroscopic constraints at earlier cosmic epochs have remained limited prior to the advent of We aim to derive the average dust attenuation law of massive log_ (JWST). Aims. 10 (M_⋆/M_⊙)>9 star-forming galaxies over the redshift range 2<z<7 using JWST spectroscopy. Methods. We combined JWST/NIRSpec spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES) survey with deep multi-wavelength photometry from the ASTRODEEP-JWST catalogues. Using a mass-selected sample of ∼ 120 galaxies with log_ 10 (M_⋆/M_⊙) > 9 and reliable Balmer decrement ( . The wavelength coverage is further extended towards the near-infrared (NIR) using JWST/MIRI photometry. measurements, we constructed stacked SEDs in bins of Balmer optical depth and derived the selective attenuation curve following the empirical methodology introduced by Calzetti_1994 Results. The resulting attenuation curve spans the rest-frame range 0.16 1.14, Our results provide a new direct empirical constraint on the average dust attenuation law for massive star-forming galaxies at 2<z<7 based on JWST spectroscopy. Despite the diversity of attenuation properties observed in individual systems, the ensemble-average behaviour remains consistent with the local starburst relation, suggesting that the main physical mechanisms regulating dust attenuation were already in place at early cosmic times. The relatively shallow UV slope compared to several previous empirical determinations may reflect differences in dust–star geometry, radiative-transfer effects, and/or effective grain-size distributions among galaxy populations. -- and is well described by a smooth function. We derived a normalisation factor of R_V ≃ 3.98, with Δ R_V = 0.16 providing an estimate of its sensitivity to the adopted long-wavelength extrapolation, finding that the average attenuation law is remarkably consistent with the local starburst relation in both slope and normalisation. However, compared to several determinations at intermediate redshift, our curve appears systematically flatter in the ultraviolet (UV). We find no significant evidence to support a 2175,Å UV bump in the average attenuation curve. Conclusions.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202660344