TY - JOUR

T1 - JWST NIRCam + NIRSpec

T2 - Interstellar medium and stellar populations of young galaxies with rising star formation and evolving gas reservoirs

AU - Tacchella, Sandro

AU - Johnson, Benjamin D.

AU - Robertson, Brant E.

AU - Carniani, Stefano

AU - D'Eugenio, Francesco

AU - Kumari, Nimisha

AU - Maiolino, Roberto

AU - Nelson, Erica J.

AU - Suess, Katherine A.

AU - Übler, Hannah

AU - Williams, Christina C.

AU - Adebusola, Alabi

AU - Alberts, Stacey

AU - Arribas, Santiago

AU - Bhatawdekar, Rachana

AU - Bonaventura, Nina

AU - Bowler, Rebecca A.A.

AU - Bunker, Andrew J.

AU - Cameron, Alex J.

AU - Curti, Mirko

AU - Egami, Eiichi

AU - Eisenstein, Daniel J.

AU - Frye, Brenda

AU - Hainline, Kevin

AU - Helton, Jakob M.

AU - Ji, Zhiyuan

AU - Looser, Tobias J.

AU - Lyu, Jianwei

AU - Perna, Michele

AU - Rawle, Timothy

AU - Rieke, George

AU - Rieke, Marcia

AU - Saxena, Aayush

AU - Sandles, Lester

AU - Shivaei, Irene

AU - Simmonds, Charlotte

AU - Sun, Fengwu

AU - Willmer, Christopher N.A.

AU - Willott, Chris J.

AU - Witstok, Joris

N1 - Publisher Copyright: © 2023 Oxford University Press. All rights reserved.

PY - 2023

Y1 - 2023

N2 - We present an interstellar medium and stellar population analysis of three spectroscopically confirmed z > 7 galaxies in the Early Release Observations JWST/NIRCam and JWST/NIRSpec data of the SMACS J0723.3-7327 cluster. We use the Bayesian spectral energy distribution-fitting code PROSPECTOR with a flexible star formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST/NIRSpec and the broad-band photometry from JWST/NIRCam, taking into account slit-loss effects. We find that these three z=7.6-8.5 galaxies (M∗~108M⊙) are young with rising SFHs and mass-weighted ages of 3-4 Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity (Zgas= 0.06 Z⊙) has a steeply rising SFH, is very compact (<0.2 kpc), and has a high star formation rate surface density (ΣSFR≈ 22 M⊙yr-1kpc-2), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicities show more complex multicomponent morphologies on kpc scales, indicating that their recent increase in star formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.

AB - We present an interstellar medium and stellar population analysis of three spectroscopically confirmed z > 7 galaxies in the Early Release Observations JWST/NIRCam and JWST/NIRSpec data of the SMACS J0723.3-7327 cluster. We use the Bayesian spectral energy distribution-fitting code PROSPECTOR with a flexible star formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST/NIRSpec and the broad-band photometry from JWST/NIRCam, taking into account slit-loss effects. We find that these three z=7.6-8.5 galaxies (M∗~108M⊙) are young with rising SFHs and mass-weighted ages of 3-4 Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity (Zgas= 0.06 Z⊙) has a steeply rising SFH, is very compact (<0.2 kpc), and has a high star formation rate surface density (ΣSFR≈ 22 M⊙yr-1kpc-2), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicities show more complex multicomponent morphologies on kpc scales, indicating that their recent increase in star formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.

KW - early Universe

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: high-redshift

KW - galaxies: star formation

U2 - 10.1093/mnras/stad1408

DO - 10.1093/mnras/stad1408

M3 - Journal article

AN - SCOPUS:85161501950

VL - 522

SP - 6236

EP - 6249

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 4

ER -