# JWST/NIRSpec Balmer-line Measurements of Star Formation and Dust Attenuation at z~3-6

**Authors:** Alice E. Shapley, Ryan L. Sanders, Naveen A. Reddy, Michael W. Topping, Gabriel B. Brammer  
**arXiv:** [2301.03241](https://arxiv.org/abs/2301.03241)  
**Date:** 2023-01-09  
**Summary page:** https://www.summarizepaper.com/en/paper/2301.03241v1/

## Key points

- Authors analyze star-formation rates (SFRs) and dust attenuation properties of star-forming galaxies at redshifts $2.7\leq z<6.5$ using data from the CEERS Survey
- Spectroscopic observations from {\it JWST}/NIRSpec MSA with resolution $R\sim1000$, covering wavelength range $1-5$$\mu$m
- Primary focus on H$\alpha$/H$\beta$ Balmer decrements as indicators of nebular dust attenuation
- Dust-corrected SFRs based on H$\alpha$ emission (SFR(H$\alpha$)) obtained by measuring these decrements
- Relationship between SFR(H$\alpha$) and stellar mass ($M_*$) constructed in three redshift bins: $2.7\leq z< 4.0$, $4.0\leq z< 5.0$, and $5.0\leq z<6.5$
- First time direct spectroscopic measurements of Balmer emission used as proxy for SFR to trace star-forming main sequence at these redshifts
- Account for subsolar metallicity prevalent among distant galaxies by using conversion factor between Hα luminosity and SFR to accurately trace relationship back to early times ($z > 3$)
- Investigate relationship between dust attenuation and stellar mass up to redshift $z \sim 6$
- No significant evolution in attenuation at fixed stellar mass found, consistent with previous studies up to $z \sim 2.3$
- Finding poses ongoing puzzle requiring further investigation given rapidly evolving gas, dust, and metal content of star-forming galaxies at fixed mass
- Study provides valuable insights into star-formation rates and dust attenuation properties of star-forming galaxies at high redshifts through direct spectroscopic measurements of Balmer emission as a proxy for SFR, allowing for more accurate characterization of star-forming main sequence in early epochs.

## Summary

In this study, the authors analyze the star-formation rates (SFRs) and dust attenuation properties of star-forming galaxies at redshifts $2.7\leq z<6.5$ using data from the Cosmic Evolution Early Release Science (CEERS) Survey. They utilize spectroscopic observations from the {\it JWST}/NIRSpec Micro-Shutter Assembly (MSA) with a resolution of $R\sim1000$, covering a wavelength range of approximately $1-5$$\mu$m. The primary focus of their analysis is on H$\alpha$/H$\beta$ Balmer decrements, which serve as indicators of nebular dust attenuation. By measuring these decrements, they are able to obtain dust-corrected SFRs based on H$\alpha$ emission (referred to as SFR(H$\alpha$)). This approach allows them to construct the relationship between SFR(H$\alpha$) and stellar mass ($M_*$) in three redshift bins: $2.7\leq z< 4.0$, $4.0\leq z< 5.0$, and $5.0\leq z<6.5$. Importantly, this represents the first time that direct spectroscopic measurements of Balmer emission have been used as a proxy for SFR to trace the star-forming main sequence at these redshifts. To accurately trace this relationship back to early times ($z > 3$), they account for subsolar metallicity prevalent among distant galaxies by using a conversion factor between Hα luminosity and SFR. Additionally, they investigate the relationship between dust attenuation and stellar mass up to redshift $z \sim 6$. Interestingly, they find that there is no significant evolution in attenuation at fixed stellar mass, consistent with previous studies that have confirmed this lack of evolution up to $z \sim 2.3$. This finding poses an ongoing puzzle that requires further investigation given the rapidly evolving gas, dust, and metal content of star-forming galaxies at fixed mass. Overall, this study provides valuable insights into the star-formation rates and dust attenuation properties of star-forming galaxies at high redshifts through direct spectroscopic measurements of Balmer emission as a proxy for SFR allowing for a more accurate characterization of the star-forming main sequence in these early epochs.