JWST/NIRCam Pa$\mathrm{\beta}$ narrow-band imaging reveals ordinary dust extinction for H$\mathrm{\alpha}$ emitters within the Spiderweb protocluster at z=2.16

TL;DR

This study uses JWST/NIRCam and Subaru/MOIRCS narrow-band imaging to analyze dust extinction and star formation in Hα emitters within the Spiderweb protocluster at z=2.16, finding typical dust levels and no environmental impact on dustiness.

Contribution

First combined Paβ and Hα imaging at this redshift to measure dust attenuation and star formation, revealing secular processes dominate dust production in this protocluster.

Findings

Most Hα emitters show nebular extinction A_V≈0-3 mag.

Dust-corrected star formation rates align with main sequence field galaxies.

No correlation between dustiness and environmental proxies.

Abstract

We combine JWST/NIRCam and Subaru/MOIRCS dual Pa$\mathrm{\beta}$ + H$\mathrm{\alpha}$ narrow-band imaging to trace the dust attenuation and the star-formation activities of a sample of 43 H$\mathrm{\alpha}$ emitters at the core of one of the most massive and best-studied clusters in formation at the cosmic noon: the Spiderweb protocluster at $\mathrm{z=2.16}$. We find that most H$\mathrm{\alpha}$ emitters display Pa$\mathrm{\beta}$/H$\mathrm{\alpha}$ ratios compatible with Case B recombination conditions, which translates into nebular extinction values ranging at $\mathrm{A_V\approx0-3}$ magnitudes, and dust corrected $\mathrm{Pa\beta}$ star formation rates consistent with coeval main sequence field galaxies at fixed stellar mass ($\mathrm{9.4<\log M_*/M_\odot<11.0}$) during this cosmic epoch. Furthermore, we investigate possible environmental impacts on dust extinction across the protocluster large-scale structure and find no correlation between the dustiness of its members and environmental proxies such as phase-space position, clustercentric radius, or local density. These results support the scenario for which dust production within the main galaxy population of this protocluster is driven by secular star formation activities fueled by smooth gas accretion across its large-scale structure. This downplays the role of gravitational interactions in boosting star formation and dust production within the Spiderweb protocluster, in contrast with observations in higher redshift and less evolved protocluster cores.