This research paper investigates the formation and evolution of barred spiral galaxies in the early Universe. The study focuses on understanding the conditions that allowed for the formation of a barred spiral galaxy, ceers-2112, at a remarkably high redshift (zphot ≈ 3), a time when the Universe was only 2 billion years old. This finding challenges existing models of galaxy formation, which predict that bar formation is suppressed at high redshifts due to the significant gas turbulence present in high-redshift disk galaxies. The research is significant because it provides observational evidence contradicting established theoretical expectations. The discovery of ceers-2112, a Milky Way progenitor with a mature barred structure at such an early epoch, allows researchers to refine models of galaxy evolution and understand the interplay between baryonic matter and dark matter in the early Universe. The study's importance lies in its potential to significantly alter our understanding of how galaxies like our own Milky Way formed and evolved over cosmic time.

The paper reviews existing literature on barred spiral galaxies, highlighting the prevalent understanding that bar formation is favored in dynamically cold stellar disks at low redshifts. Studies like Erwin (2018) and Pérez-Villegas et al. (2020) demonstrate the correlation between bar frequency and galaxy properties at low redshift. However, high-redshift galaxies are typically characterized by significant gas turbulence, a factor that is thought to suppress or delay bar formation (Tacconi et al., 2020). Simulations, such as those from Zhou et al. (2020), Zana et al. (2022), and Reddish et al. (2022), largely support this prediction, indicating a near absence of bars beyond z = 1.5 in Milky Way-like galaxy progenitors. The discovery of ceers-2112 directly challenges this established theoretical framework, necessitating a reevaluation of the processes involved in galaxy formation and bar development in the early Universe. Previous studies on high redshift galaxies, such as Rizzo et al. (2020) and Lelli et al. (2021), have reported the existence of dynamically cold disk galaxies at high redshift, suggesting that the conditions for bar formation may be more prevalent than previously thought.

The researchers utilized multiwavelength data from the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam) and Hubble Space Telescope (HST) data. JWST/NIRCam images from the Cosmic Evolution Early Release Science (CEERS) campaign, specifically the NIRCam1 pointing, provided the primary data. Seven filters (F115W, F150W, F200W, F277W, F356W, F410M, F444W) were used to construct a stacked image to enhance signal-to-noise ratio, particularly in the outer, lower surface brightness regions. HST images (F606W, F814W, F125W, F140W, F160W) from the CANDELS survey were incorporated to extend the wavelength coverage. Morphological analysis involved several techniques: isophotal analysis to trace the galaxy's brightness distribution and identify its shape and structure, Fourier decomposition to separate the azimuthal luminosity distribution into components (identifying the m=2 component as indicative of a bar), single-component Sérsic modeling to highlight structural residuals, and two-component (bar + disk) photometric decomposition to quantify bar parameters such as length and strength. The photometric redshift was determined using EAZYpy, and stellar population properties (star formation history, stellar mass, mass-weighted age) were derived using SED fitting with the synthesizer code. The analysis also involved comparison of ceers-2112 with the assembly history of Milky Way progenitors to establish its evolutionary context. The researchers carefully considered potential sources of error, using Monte Carlo simulations and multiple software packages to validate their findings. Various methods were employed for deprojection to account for the galaxy’s inclination angle.

The main finding is the unambiguous identification of ceers-2112 as a barred spiral galaxy at a photometric redshift of zphot = 3.03 ± 0.05. This places the galaxy's existence at a time when the Universe was only about 2 billion years old. The galaxy's stellar mass is estimated to be 3.9 × 10¹⁰ M⊙, placing it firmly within the category of Milky Way progenitors. The bar's length is estimated to be 3.3 kpc. Multiple independent analyses (isophotal analysis, Fourier decomposition, Sérsic residual analysis, and bar + disk decomposition) consistently confirm the barred morphology. The analysis of the galaxy's star formation history indicates a mass-weighted age of 620 ± 150 Myr, implying a relatively rapid assembly. The finding strongly suggests that dynamically cold stellar disks could form much earlier in the Universe's history than previously thought, with the stellar disk of ceers-2112 possibly assembling at z ≈ 5 and the bar component forming approximately 200 Myr later. The presence of a bar at such an early epoch implies that baryonic matter (normal matter) may have dominated over dark matter in this galaxy as early as z = 3. The formation timescale of the bar is estimated to be about 400 Myr. This rapid bar formation is further supported by the analysis of the star formation history, revealing a fast episode of gas consumption at z ≈ 4, which led to a dynamically cold and bar-unstable disk.

The discovery of ceers-2112 fundamentally challenges the current understanding of galaxy formation and evolution at high redshift. The presence of a mature barred structure in a Milky Way-like galaxy at z ≈ 3 necessitates revisions to models that predict suppressed bar formation due to gas turbulence. The rapid bar formation timescale (≈400 Myr) requires further investigation into the processes involved. The results suggest that baryons could have dominated over dark matter in ceers-2112 at z = 3. The study highlights the need for cosmological simulations that accurately model baryon-dominated disks, early cold disk formation, and rapid bar formation at high redshifts. The rapid gas consumption indicated by the star formation history offers a potential mechanism that led to the bar formation. Future research should focus on high-resolution simulations and observations to improve our understanding of the interplay between gas abundance, star formation efficiency, and bar formation at high redshift.

This paper presents the discovery of ceers-2112, a barred spiral galaxy at z ≈ 3, significantly pushing back the timeframe for bar formation in Milky Way-like galaxies. The findings challenge existing models and highlight the need for revised theoretical frameworks that account for early cold disk formation and rapid bar development. Future research should focus on refining cosmological simulations to reproduce such systems, and conducting deeper observational studies to further investigate the prevalence of high-redshift barred galaxies. This study underscores the importance of continued JWST observations to probe the early Universe's galaxy population.

The study relies on photometric redshift estimations, which may introduce uncertainties. The morphological analysis is subject to limitations imposed by the resolution of the telescope. The interpretation of the star formation history depends on assumptions made in the SED fitting. The small sample size of high-redshift barred galaxies limits statistical generalizability. While several independent methods are used to confirm the presence of the bar, the exact mechanisms for the rapid bar formation remain speculative.