Early Results from GLASS-JWST. XXV. Electron Density in the Interstellar Medium at 0.7 ≲ z ≲ 9.3 with NIRSpec High-resolution Spectroscopy

January 2025 • 2025ApJ...979L..13L

Authors • Li, Sijia • Wang, Xin • Chen, Yuguang • Jones, Tucker • Treu, Tommaso • Glazebrook, Karl • He, Xianlong • Henry, Alaina • Meng, Xiao-Lei • Morishita, Takahiro • Roberts-Borsani, Guido • Yang, Lilan • Yu, Hao-Ran • Calabrò, Antonello • Castellano, Marco • Leethochawalit, Nicha • Metha, Benjamin • Nanayakkara, Themiya • Roy, Namrata • Vulcani, Benedetta

Abstract • The electron density (n_e) of the interstellar medium (ISM) in star-forming galaxies is intimately linked to star formation and ionization condition. Using the high-resolution spectra obtained from the JWST Near-Infrared Spectrograph (NIRSpec) microshutter assembly (MSA) as part of the GLASS-JWST program, we have assembled the largest sample to date (34 galaxies) with individual n_e measurements derived from the [O II] λλ3726, 29 and/or [S II] λλ6718, 32 doublets at 0.7 ≲ z ≲ 9.3. The gravitational lensing magnification by the foreground A2744 cluster allows us to probe n_e in galaxies with stellar masses (M_*) down to ≃10^7.5 M_⊙ across the entire redshift range. Our analysis reveals that the [O II] flux ratios are marginally anticorrelated with a specific star formation rate (sSFR) within a 1σ confidence interval, whereas the [S II] flux ratios show no significant correlation with sSFR. Despite a clear correlation between sSFR and redshift within our sample, we find no apparent redshift evolution of n_e at z ≃ 1–9. Our data set also includes 13 galaxies where n_e can be measured from both [O II] and [S II]. Contrary to findings at lower redshifts, we observe considerable scatter in n_e measurements from [O II] and [S II], indicating a complex gaseous environment with significant variations in n_e in high-redshift galaxies. This work highlights the unique capability of JWST NIRSpec/MSA high-resolution spectroscopy to characterize the detailed physical properties of the ISM in individual high-redshift galaxies. *Based on observations acquired by the JWST under the ERS program ID 1324 (PI: T. Treu).

Links

• PDF https://iopscience.iop.org/article/10.3847/2041-8213/ad9eac/pdf
• DATA https://doi.org/10.17909/kw3c-n857
• ELECTR https://iopscience.iop.org/article/10.3847/2041-8213/ad9eac
• PREPRINT http://arxiv.org/abs/2412.08382