SMILES Data Release II: Probing Galaxy Evolution during Cosmic Noon and Beyond with NIRSpec Medium-Resolution Spectra

Yongda Zhu, Nina Bonaventura, Yang Sun, George H. Rieke, Stacey Alberts, Jianwei Lyu, Irene Shivaei, Jane E. Morrison, Zhiyuan Ji, Eiichi Egami, Jakob M. Helton, Marcia J. Rieke, Pierluigi Rinaldi, Fengwu Sun, Christopher N. A. Willmer

First listed 2025-08-18 | Last updated 2025-12-09

Abstract

We present the second data release of the Systematic Mid-Infrared Instrument (MIRI) Legacy Extragalactic Survey (SMILES), focusing on JWST/NIRSpec medium-resolution spectroscopy of galaxies across cosmic time. This release includes spectroscopic observations of 166 galaxies spanning $0 < z < 7.5$, sampling star-forming galaxies, quiescent systems, and active galactic nuclei (AGN), with an emphasis on galaxies at cosmic noon ($z \sim 1$-3). We describe the target selection strategy, the observational setup with the G140M/F100LP and G235M/F170LP gratings, and the data calibration process. The final data products include the reduced spectra, redshift catalog, emission-line catalogs produced with \texttt{GELATO} for emission-line galaxies and \texttt{pPXF} fits for quiescent systems, and ancillary spectral energy distribution (SED) fit results derived from multi-band photometry. The SMILES NIRSpec dataset enables investigations of obscured AGN, multi-phase outflows, ionizing properties, and the role of environment in galaxy evolution.

Short digest

SMILES DR2 releases medium-resolution NIRSpec MSA spectra for 166 GOODS-S/HUDF galaxies spanning 0<z<7.5, with a strong emphasis on cosmic noon (z~1–3). Using the G140M/F100LP and G235M/F170LP settings to provide contiguous ~1–3 µm coverage (split near 1.8 µm), the team delivers reduced 1D/2D spectra, robust redshifts, emission-line catalogs (GELATO) and pPXF fits for quiescents, plus ancillary SED results. The dataset is tuned to capture rest‑optical diagnostics for dusty and obscured systems, enabling work on AGN, multi‑phase outflows, excitation, and metallicity in environmental context. Public HLSP availability makes this a ready benchmark set for cosmic‑noon black‑hole growth and ISM studies.

Key figures to inspect

• Figure 1 — Survey footprint and overlaps: verify where SMILES MSA slitlets land within GOODS‑S/HUDF and how coverage intersects FRESCO and JADES; note Chandra/JVLA overlap that will power obscured‑AGN and outflow cross‑checks.
• Figure 2 — Example spectra across gratings: inspect the star‑forming, AGN (broad H emission), and quiescent templates to gauge line coverage/resolution across the ~1.8 µm grating boundary and the feasibility of [O III]/Hβ, Hα+[N II] diagnostics.
• Figure 3 — 1/f noise mitigation: compare pre‑/post‑correction 2D frames to see how Chebyshev column fits remove vertical banding and improve background uniformity, crucial for faint continuum and low‑EW lines.
• Figure 4 — Nod strategy for extended sources: assess how the modified 2‑nod extraction (ID 199580) preserves extended flux versus the standard 3‑nod, yielding a stronger H peak—important for diffuse/outflow components.