2025/02/12 by Michael W. Topping, Topping, Michael W., Ryan L. Sanders +31 · 1 citation
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Geophysics and Gravity Measurements #Particle Accelerators and Free-Electron Lasers #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.2502.08712
openalex publication_date 2025/02/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present an analysis of deep JWST/NIRSpec spectra of star-forming galaxies at z≃1.4-10, observed as part of the AURORA survey. We infer median low-ionization electron densities of 268-49+45~\rm cm-3, 350-76+140~\rm cm-3, and 480-310+390~\rm cm-3 at redshifts z=2.3, z=3.2, and z=5.3, respectively, revealing an evolutionary trend following (1+z)1.5±0.6. We identify weak positive correlations between electron density and star formation rate (SFR) as well as SFR surface density, but no significant trends with stellar mass or specific SFR. Correlations with rest-optical emission line ratios show densities increasing with \rm [NeIII]λ3869/[OII]λ3727 and, potentially, \rm [OIII]λ5007/[OII]λ3727, although variations in dust attenuation complicate the latter. Additionally, electron density is more strongly correlated with distance from the local BPT sequence than can be explained by simple photoionization models. We further derive electron densities from the CIII] doublet probing higher-ionization gas, and find a median value of 1.4-0.5+0.7×104~\rm cm-3, ∼30 times higher than densities inferred from [SII]. This comparison suggests a consistent HII region structure across cosmic time with dense, high-ionization interiors surrounded by less dense, low-ionization gas. We compare measurements of AURORA galaxies to predictions from the SPHINX galaxy formations, highlighting the interplay between residual molecular cloud pressure in young galaxies and feedback from stellar winds and supernovae as galaxies mature.