Spatially resolved nebular-stellar reddening with JWST/NIRISS

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Abstract
An accurate determination of dust attenuation within galaxies is essential for deriving key physical properties such as the star formation rate (SFR). We present an analysis using the JWST/NIRISS data from the GLASS-JWST ERS programme to investigate and characterise the stellar and nebular reddening of galaxies at 1.0 < z < 2.4 down to the sub-kiloparsec scale. We used a multiregion fitting method to extract high-quality H α and H β emission line maps for 99 individual galaxies across a stellar mass range 7.0 < log 10 ( M * /M ⊙ ) ≲ 10.5. We find no evidence for ratios of the Balmer decrement (H α /H β ) below the intrinsic limit for Case B recombination, beyond the expected variation from observational uncertainties. We reproduce the local correlation between the Balmer decrement and total stellar mass, and find no measurable difference when splitting the sample by redshift, with negligible attenuation below log 10 ( M * /M ⊙ ) ≲ 8.5. Similarly, the best-fit relation between the nebular and continuum reddening follows the same relation as in local starburst galaxies, E ( B − V ) SED = (0.46 ± 0.02) E(B − V ) neb , together indicating no significant evolution in the dust geometry within galaxies out to z ≲ 2.4. We derive best-fit linear relations between the differential nebular-stellar reddening and the spectral-energy-distribution-derived SFR and stellar mass, finding statistically significant relations for both quantities. We used our spatially resolved measurements to derive an empirical calibration between the resolved differential reddening, and the SFR surface density. These will enable crucial dust attenuation corrections for spatially resolved science at higher redshifts where the Balmer lines are inaccessible, such as with future Roman grism observations.
Funding Information
  • NASA (JWST-ERS-1324)
  • Istituto Nazionale di Astrofisica (Extragalactic Surveys with JWST)
  • NextGenerationEU (RFF M4C2 1.1 PRIN 2022 project 2022ZSL4BL INSIGHT)
  • Istituto Nazionale di Astrofisica (1.05.24.07.01 RSN1: "Spatially Resolved Near-IR Emission of Intermediate-Redshift Jellyfish Galaxies")

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