What the study found
Dust-attenuation curves in galaxies vary strongly, and they become flatter at higher attenuation and at higher redshift. The highest-redshift galaxies in the sample, at redshift 7-9, had attenuation-curve slopes flatter than the Calzetti curve, a commonly used reference curve for dust in galaxies.
Why the authors say this matters
The authors say dust-attenuation curves are key for interpreting the intrinsic properties of galaxies and for understanding dust grains and their geometry relative to stars. The findings suggest that dust in high-redshift galaxies may be increasingly dominated by large grains produced in supernova ejecta with limited interstellar medium processing at early times.
What the researchers tested
The researchers constrained the ultraviolet-optical dust-attenuation curve slope in a spectroscopic-redshift sample of about 3,800 galaxies at redshift 1-9. They used galaxies from three JWST/NIRCam grism surveys in the GOODS-S, GOODS-N, and Abell-2744 fields, along with JWST/NIRCam and HST photometry, and applied Bayesian spectral energy distribution fitting with a flexible dust model.
What worked and what didn't
The study found strong evidence that, at fixed attenuation, the attenuation curve becomes flatter with increasing redshift. On average, the derived curves were shallower than those at redshift about 0 and shallower than the SMC curve. The authors also report no strong correlation between attenuation-curve slope and size or axis ratio, and they say the trends with stellar mass and star-formation rate are largely driven by their correlation with attenuation.
What to keep in mind
The abstract does not describe detailed limitations beyond the scope of the sample and redshift range studied. The reported conclusions are based on the available spectroscopic-redshift sample and the flexible dust model used in the analysis.
Key points
- Dust-attenuation curves vary strongly across the galaxy sample.
- At fixed attenuation, the curve slope becomes flatter with increasing redshift.
- The z = 7-9 galaxies have slopes flatter than the Calzetti curve.
- The study found no strong correlation between slope and size or axis ratio.
- The authors suggest high-redshift dust may be dominated by large grains from supernova ejecta.
Disclosure
- Research title:
- Dust-attenuation curves flatten with higher redshift
- Image credit:
- Photo by Guillermo Ferla on Unsplash
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