JWST/NIRCam Paβ Narrowband Imaging Reveals Ordinary Dust Extinction for Hα Emitters within the Spiderweb Protocluster at z = 2.16

Abstract We combine JWST/NIRCam and Subaru/MOIRCS dual Pa β +H α narrowband imaging to trace the dust attenuation and the star formation activities of a sample of 43 H α emitters at the core of one of the most massive and best-studied clusters in formation at the cosmic noon: the Spiderweb protocluster at z = 2.16. We find that most H α emitters display Pa β /H α ratios compatible with Case B recombination conditions, which translates into nebular extinction values ranging at A V ≈ 0–3 mag, and dust corrected Pa β star formation rates consistent with coeval main sequence field galaxies at fixed stellar mass ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>9.4</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mi>log</mml:mi> <mml:mspace width="0.33em"/> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic">M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic">M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>&lt;</mml:mo> <mml:mn>11.0</mml:mn> </mml:math> ) 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.