Photometric detection at $7.7\ μ\mathrm{m}$ of a galaxy beyond redshift $14$ with JWST/MIRI

Abstract: The James Webb Space Telescope (JWST) has spectroscopically confirmed numerous galaxies at $z > 10$. While weak rest-ultraviolet emission lines have only been seen in a handful of sources, the stronger rest-optical emission lines are highly diagnostic and accessible at mid-infrared wavelengths with the Mid-Infrared Instrument (MIRI) of JWST. We report the photometric detection of the distant spectroscopically confirmed galaxy JADES-GS-z14-0 at $z = 14.32^{+0.08}_{-0.20}$ with MIRI at $7.7\ \mu\mathrm{m}$. The most plausible solution for the stellar population properties is that this galaxy contains half a billion solar masses in stars with a strong burst of star formation in the most recent few million years. For this model, at least one-third of the flux at $7.7\ \mu\mathrm{m}$ comes from the rest-optical emission lines $\mathrm{H}\beta$ and/or $\mathrm{[OIII]}\lambda\lambda4959,5007$. The inferred properties of JADES-GS-z14-0 suggest rapid mass assembly and metal enrichment during the earliest phases of galaxy formation. This work demonstrates the unique power of mid-infrared observations in understanding galaxies at the redshift frontier.

• The paper demonstrates ultra-deep JWST/MIRI photometry detecting 7.7 μm rest-frame optical emission lines in a z>14 galaxy.
• It employs SED modeling with BAGPIPES and Prospector to estimate stellar mass and contrast star formation histories.
• The findings challenge early universe formation theories by revealing intense star formation and rapid mass assembly soon after the Big Bang.

Analysis of JWST/MIRI Photometric Detection in a High-Redshift Galaxy

The paper presents a significant astrophysical discovery achieved using the James Webb Space Telescope's Mid-Infrared Instrument (JWST/MIRI). The focal point of this study is the galaxy JADES-GS-z14-0, which resides at a redshift of $z = 14.32^{+0.08}_{-0.20}$. This places the galaxy in an era approximately 300 million years after the Big Bang, marking one of the most distant spectroscopically confirmed galaxies to date.

Key Observations and Methodologies

The detection of JADES-GS-z14-0 at $7.7\ \mu\mathrm{m}$ was accomplished through ultra-deep photometric observations. The MIRI instrument, sensitive to mid-infrared wavelengths, captures rest-frame optical emission lines that are inaccessible to other instruments like NIRCam and NIRSpec. The study identifies that a substantial portion of the observed $7.7\ \mu\mathrm{m}$ flux originates from the emission lines $\mathrm{H}\beta$ and $\mathrm{[OIII]}\lambda\lambda4959,5007$.

Stellar Population Analysis

The research deploys spectral energy distribution (SED) modeling using tools such as BAGPIPES and Prospector to infer stellar population parameters. These models suggest that JADES-GS-z14-0 hosts roughly half a billion solar masses in stars, with a recent intense burst of star formation. The BAGPIPES model favored solutions point towards younger stellar populations with notable dust attenuation, whereas Prospector implies older stellar ages with little to no recent star formation and significantly higher stellar mass estimations.

Scientific Implications

The findings challenge pre-existing conceptual frameworks regarding the early universe's galaxy formation processes. The detection of intense star-forming activity and early metal enrichment during the cosmic dawn raises questions about rapid mass assembly mechanisms in the early universe. These observations indicate that the galaxy's early formation and massive stellar mass may not align with theories extrapolated from lower redshifts.

Methodological Rigor

The study's approach includes a robust methodology for photometric measurement, involving model fitting to distinguish contributions from JADES-GS-z14-0 and a proximate foreground galaxy. The validation of photometric techniques ensures consistency across different models and assumptions about the galaxy's intrinsic properties.

Future Directions

Further spectroscopic follow-up with JWST/MIRI is deemed essential to confirm and expand upon these results. Such investigations will refine the understanding of nebular emission contributions and facilitate a detailed exploration of star formation rates, potentially providing opportunities to capture these phenomena across broader cosmic timelines. These spectral studies will offer deeper insights into the role of such high-redshift galaxies in reionization and the broader evolution of the universe.

The paper's findings represent a compelling advancement in the field of observational cosmology, highlighting the unprecedented capabilities of JWST in probing the cosmic dawn and pushing the limits of current astrophysical models. This work underscores the importance of integrating deep photometric and spectroscopic data to unravel the complexities of early galaxy formation and evolution.