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Literature
Date: 1/28/2025

Arxiv: The AURORA Survey: A New Era of Emission-line Diagrams with JWST/NIRSpec Published: 6/28/2024 9:00:05 PM Updated: 1/26/2025 12:02:06 AM

Paper abstract: We present results on the emission-line properties of z=1.4-7.5 star-forminggalaxies in the Assembly of Ultradeep Rest-optical Observations RevealingAstrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based on its depth,continuous wavelength coverage from 1--5 microns, and medium spectralresolution (R~1000), AURORA includes detections of a large suite of nebularemission lines spanning a broad range in rest wavelength. We investigate thelocations of AURORA galaxies in multiple different emission-line diagrams,including traditional "BPT" diagrams of [OIII]/Hbeta vs. [NII]/Halpha,[SII]/Halpha, and [OI]/Halpha, and the "ionization-metallicity" diagram of[OIII]/[OII] (O32) vs. ([OIII]+[OII])/Hbeta (R23). We also consider a bluerrest-frame "ionization-metallicity" diagram introduced recently to characterizez>10 galaxies: [NeIII]/[OII] vs. ([NeIII]+[OII])/Hdelta; as well aslonger-wavelength diagnostic diagrams extending into the rest-frame near-IR:[OIII]/Hbeta vs. [SIII]/[SII] (S32); and HeI/Pagamma and [SIII]/Pagamma vs.[FeII]/Pabeta. With a significant boost in signal-to-noise and large,representative samples of individual galaxy detections, the AURORAemission-line diagrams presented here definitively confirm a physical picturein which chemically-young, alpha-enhanced, massive stars photoionize the ISM indistant galaxies with a harder ionizing spectrum at fixed nebular metallicitythan in their z~0 counterparts. We also uncover previously unseen evolutionprior to z~2 in the [OIII]/Hbeta vs. [NII]/Halpha diagram, which motivates deepNIRSpec observations at even higher redshift. Finally, we present the firststatistical sample of rest-frame near-IR emission-line diagnostics instar-forming galaxies at high redshift. In order to truly interpret rest-framenear-IR line ratios including [FeII], we must obtain better constraints on dustdepletion in the high-redshift ISM.