Galaxy mergers are key drivers of galaxy formation and evolution, including triggering active galactic nucleus (AGN) and star formation to a still unknown degree. We thus investigate the impact of galaxy mergers on star formation and AGN activity using 3330 galaxies at z = 4.5-8.5 from eight James Webb Space Telescope fields (CEERS, JADES GOODS-S, NEP-TDF, NGDEEP, GLASS, El-Gordo, SMACS-0723, and MACS-0416), covering an unmasked area of 189 arcmin(2). We focus on star formation rate (SFR) enhancement, AGN fraction, and AGN excess in close pairs defined by Delta z < 0.3 and projected separations r(p) < 100 kpc, relative to non-merger samples. Close pairs with mass ratios greater than 1:4 are used for the SFR-enhancement analysis, whereas no mass-ratio constraint is applied for the AGN fraction and AGN excess measurements. We find SFR enhancement occurs only at r(p) < 20 kpc, with values 0.25 +/- 0 .10 dex and 0 .26 +/- 0 .11 dex above non-merger medians for z = [4.5 , 6.5] and z = [6.5 , 8.5] , respectively. No other statistically significant enhancements in galaxy sSFR or stellar mass are observed at any projected separation or redshift. We also compare observational results with predictions from the SC-SAM simulation, finding no evidence of star formation enhancement in simulations at any separation. Lastly, we examine the fraction and excess of AGNs identified through photometric spectral energy distributions (SED) fitting (Type-I) and BPT diagnostics (Type-II). We find 48(-7)(+33) % of Type-I and 44(-20)(+26)% of Type-II AGNs have a close companion within r(p) < 50 kpc and Delta z < 0.3.Furthermore, 73(-32)( +27)% of AGNs have companions within 100 kpc. Relative to isolated galaxies, we measure an AGN excess factor of 1.26(-0.04)(+0.15 )for Type-I and 1.34(-0.11 )(+0.23)for Type-II AGNs in close pairs, suggesting notable AGN enhancement in galaxy pairs at these higher redshifts.

We present the results of a machine learning study to measure the dust content of galaxies observed with JWST at z > 6 through the use of trained neural networks based on high-resolution IllustrisTNG simulations. Dust is an important unknown in the evolution and observability of distant galaxies and is degenerate with other stellar population features through spectral energy fitting. As such, we develop and test a new SED-independent machine learning method to predict dust attenuation and sSFR of high redshift (z > 6) galaxies. Simulated galaxies were constructed using the IllustrisTNG model, with a variety of dust contents parameterized by E(B-V) and A(V) values, then used to train Convolutional Neural Network (CNN) models using supervised learning through a regression model. We demonstrate that within the context of these simulations, our single and multi-band models are able to predict dust content of distant galaxies to within a 1$\sigma$ dispersion of A(V) $\sim 0.1$. Applied to spectroscopically confirmed z > 6 galaxies from the JADES and CEERS programs, our models predicted attenuation values of A(V) < 0.7 for all systems, with a low average (A(V) = 0.28). Our CNN predictions show larger dust attenuation but lower amounts of star formation compared to SED fitted values. Both results show that distant galaxies with confirmed spectroscopy are not extremely dusty, although this sample is potentially significantly biased. We discuss these issues and present ideas on how to accurately measure dust features at the highest redshifts using a combination of machine learning and SED fitting.

We develop a photometric search method for identifying smouldering galaxies at 5 < z < 8, which are defined to have weak emission lines and thus generally have low specific star formation rates and may even be in a state of (temporary) quiescence. The deep NIRCam imaging (similar to 29.5 AB mag, 5 Q) from the JADES second data release is essential for finding these systems, as they are faint, relatively quiescent dwarf galaxies (M & lowast; similar to 10(8 -9) M-circle dot) in the Epoch of Reionization (EoR). Moreover, medium band imaging is key, enabling a clear identification of the lack of emission lines in these galaxies, thus betraying their dormant flame. Owing to the young age of the Universe, combined with the likely bursty star formation in these first dwarf galaxies, conventional colour-selection methods like the UVJ diagram likely miss a large fraction of the quiescent population in the EoR. Indeed, we find that smouldering galaxies constitute a considerable fraction (0.05-0.35) of the EoR dwarf galaxy population (M & lowast; similar to 10(8 -9) M-circle dot). As predicted by simulations, these first dwarf galaxies are fragile, the star formation in their shallow potential wells easily snuffed out by feedback-driven winds triggered by secular or merger-driven starbursts, with the smouldering fraction increasing with decreasing stellar mass. Finally, we provide observational constraints on the smouldering galaxy comoving number density (similar to 10(-4) -10(-5) dex(-1) Mpc(-3)), which, although hampered by incompleteness, should aid in our understanding of the primordial baryon cycle, as current simulations greatly disagree on whether these systems are rare (similar to 1 per cent ) or common (similar to 50 per cent ) in the EoR.

In this paper, we describe our search for galaxy protocluster candidates at 4.54.5 galaxy candidates within an area of 185.4 arcmin(2). We determine nearest neighbour statistics and galaxy environments. We find that high-z galaxies in overdense environments exhibit higher star formation activity compared to those in underdense regions. Galaxies in dense environments have a slightly increased star formation rate (SFR) at a given mass compared with galaxies in the lower density environments. At the high-mass end, we also find a gradual flattening of the M-star-SFR slope. We find that galaxies in high-density regions often have redder ultraviolet slopes than those in low-density regions, suggesting more dust extinction, weaker Ly alpha emission, and/or a higher damped Ly alpha absorption. The mass-size relation shows a weak positive correlation between galaxy size and local density. Furthermore, we quantitatively assess the probability of a galaxy belonging to a protocluster candidate. In total, we identified 26 overdensities at z=5-7 and estimate their dark matter halo masses. We find that all proto-cluster candidates could evolve into clusters with M-halo>10(14)M(circle dot) at z=0, thereby supporting the theoretical and simulation predictions of cluster formation. Notably, this marks an early search for protocluster candidates in JWST wide field based on photometric data, providing valuable candidates to study cosmic structure formation at the early stages.

We present a full analysis of galaxy major merger pair fractions, merger rates, and mass accretion rates, thus uncovering the role of mergers in galaxy formation at the earliest previously unexplored epoch of 4.5 < z < 11.5. We target galaxies with masses log10 (M-*/M-circle dot) = 8.0-10.0, utilizing data from eight JWST Cycle-1 fields [CEERS (Cosmic Evolution Early Release Science Survey), JADES (JWST Advanced Deep Extragalactic Survey) GOODS-S, NEP-TDF (North Ecliptic Pole Time-Domain Field), NGDEEP (Next-Generation Deep Extragalactic Exploratory Public Survey), GLASS (Grism Lens Amplified Survey from Space), El-Gordo, SMACS-0723, MACS-0416], covering an unmasked area of 189.36 arcmin2. We develop a new probabilistic pair-counting methodology that integrates full photometric redshift posteriors and corrects for detection incompleteness to quantify close pairs with physical projected separations between 20 and 50 kpc. Our analysis reveals an increase in pair fractions up to z=8, reaching 0.211 +/- 0.065, followed by a statistically flat evolution to z=11.5. We find that the galaxy merger rate increases from the local Universe up to z=6 and then stabilizes at a value of similar to 6 Gyr(-1) up to z=11.5. The redshift evolution of both pair fractions and merger rates is well described by a power-law plus exponential model. In addition, we measure that the average galaxy increases its stellar mass due to mergers by a factor of 2.77 +/- 0.99 from redshift z=10.5 to z=5.0. Lastly, we investigate the impact of mergers on galaxy stellar mass growth, revealing that mergers contribute as much as 71 +/- 25 per cent to galaxy stellar mass growth. This indicates that mergers drive about half of galaxy assembly at high redshift.

We explore spectroscopic and photometric methods for identifying high-redshift galaxies containing an active galactic nucleus (AGN) with James Webb Space Telescope (JWST) observations. After demonstrating the limitations of standard optical methods, which appear ineffective in the low-metallicity environment of the early universe, we evaluate alternative diagnostics using current JWST capabilities. Our analysis focuses on line ratios and equivalent widths (EWs) of ultraviolet (UV) lines: C iv, He ii $\lambda$1640, O iii] $\lambda$1665, and C iii], and the faint optical line He ii $\lambda$4686. We find that the most valuable diagnostic quantities for identifying AGN are the ratios (C iii] + C iv)/He ii $\lambda$1640 and C iii]/He ii $\lambda$1640, as well as the EW of He ii $\lambda$1640. For more reliable AGN identification, He ii $\lambda$1640 and O iii] $\lambda$1665 should be detected separately. The He ii $\lambda$1640/H$\beta$ ratio effectively separates AGN from star-forming galaxies, although it depends on low dust content. We also show that to use these diagnostics effectively, future observations require longer exposure times, especially at z > 6. We plot three high-redshift sources with strong UV emission on these diagrams; however, further study is needed to classify them as AGN candidates due to He ii + O iii] blending and unreliable optical lines. Finally, we select AGN candidates in the JWST Advanced Deep Extragalactic Survey (JADES) Near Infrared Camera photometry using spectral energy distribution fitting with eazy. One galaxy emerges as a strong AGN candidate, supported by both photometric selection and strong UV emission, and we present a sample of similar candidates in the JADES data using this method.

We utilize deep JWST Near Infrared Camera (NIRCam) observations for the first direct constraints on the Galaxy Stellar Mass Function (GSMF) at z > 10. Our EPOCHS v1 sample includes 1120 galaxy candidates at 6.5 < z < 13.5 taken from a consistent reduction and analysis of publicly available deep JWST NIRCam data covering the Prime Extragalactic Areas for Reionization Science, CEERS, GLASS, JADES GOOD-S, NGDEEP, and SMACS0723 surveys, totaling 187 arcmin2. We investigate the impact of spectral energy distribution fitting methods, assumed star formation histories (SFHs), dust laws, and priors on galaxy masses and the resultant GSMF. While our fiducial GSMF agrees with the literature at z < 13.5, we find that the assumed SFH model has a large impact on the GSMF and stellar mass density (SMD), finding a 0.75 dex increase in the SMD at z = 10.5 between a flexible nonparametric and standard parametric SFH. Overall, we find a flatter SMD evolution at z >= 9 than some studies predict, suggesting a rapid buildup of stellar mass in the early Universe. We find no incompatibility between our results and those of standard cosmological models, as suggested previously, although the most massive galaxies may require a high star formation efficiency. We find that the "little red dot" galaxies dominate the z = 7 GSMF at high masses, necessitating a better understanding of the relative contributions of active galactic nucleus and stellar emission. We show that assuming a theoretically motivated top-heavy initial mass function (IMF) reduces stellar mass by 0.5 dex without affecting fit quality, but our results remain consistent with existing cosmological models with a standard IMF.

We present an analysis of rest-frame UV continuum slopes, β , using a sample of 1011 galaxies at 6.5 < z < 13 from the EPOCHS photometric sample collated from the GTO PEARLS and public ERS/GTO/GO (JADES, CEERS, NGDEEP, GLASS) JWST/NIRCam imaging across 178.9 arcmin 2 of unmasked blank sky. We correct our UV slopes for the photometric error coupling bias using 200,000 power-law spectral energy distributions for each β = {−1, −1.5, −2, −2.5, −3} in each field, finding biases as large as Δ β ≃ −0.55 for the lowest signal-to-noise ratio galaxies in our sample. Additionally, we simulate the impact of rest-UV line emission (including Ly α ) and damped Ly α systems on our measured β , finding biases as large as 0.5–0.6 for the most extreme systems. We find a decreasing trend with redshift of β = −1.51 ± 0.08 − (0.097 ± 0.010) × z , with potential evidence for Population III stars or top-heavy initial mass functions in a subsample of 68 β + σ β < −2.8 galaxies. At z ≃ 11.5, we measure an extremely blue β ( M UV = −19) = −2.73 ± 0.06, deviating from simulations, indicative of low-metallicity galaxies with nonzero Lyman continuum escape fractions f esc,LyC ≳ 0 and minimal dust content. The observed steepening of d β / d log 10 ( M ⋆ / M ⊙ ) from 0.22 ± 0.02 at z ≃ 7 to 0.81 ± 0.13 at z ≃ 11.5 implies that dust produced in core-collapse supernovae at early times may be ejected via outflows from low-mass galaxies. We also observe a flatter d β / d M UV = 0.03 ± 0.02 at z ≃ 7 and a shallower d β / d log 10 ( M ⋆ / M ⊙ ) at z < 11 than seen by the Hubble Space Telescope, unveiling a new population of low-mass, faint galaxies reddened by dust produced in the stellar winds of asymptotic giant branch stars or carbon-rich Wolf–Rayet binaries.

We present a structural analysis of 520 galaxy candidates at 6.5 < z < 12.5 with a signal-to-noise ratio of >10 σ in the F444W filter taken from the EPOCHS v1 sample, consisting of uniformly reduced deep JWST NIRCam data covering the CEERS, JADES GOODS-S, NGDEEP, SMACS-0723, GLASS, and PEARLS surveys. We use standard software to fit single Sérsic models to each galaxy in the rest-frame optical and extract their parametric structural parameters (Sérsic index, half-light radius, and axis ratio) and Morfometryka to measure their nonparametric concentration and asymmetry parameters. We find a wide range of sizes for these early galaxies, with galaxy sizes overall continuing to become progressively smaller in the high-redshift regime, following R e = 2.12 ± 0.28 1 + z − 0.67 ± 0.06 kpc. We further find a galaxy size–mass correlation up to z ∼ 12, with galaxies of a given mass also becoming smaller. Using nonparametric methods, we find that galaxy merger fractions, classified through asymmetry parameters, at these redshifts remain consistent with those in the literature, maintaining a value of f m ∼ 0.12 ± 0.07 showing little dependence with redshift when combined with the literature at z > 4. We find that galaxies that are smaller in size also appear rounder, with an excess of high axis ratio objects. Finally, we artificially redshift a subsample of our objects to determine how robust the observational trends we see are, determining that the observed trends are due to real evolutionary effects, rather than being a consequence of redshift effects.

We present in this paper the discovery, properties, and a catalog of 1165 high-redshift 6.5 < z < 18 galaxies found in deep JWST NIRCam imaging from the GTO PEARLS survey combined with data from JWST public fields. We describe our bespoke homogeneous reduction process and our analysis of these areas including the NEP, CEERS, GLASS, NGDEEP, JADES, and ERO SMACS-0723 fields with over 214 arcmin ^2 imaged to depths of ∼30 mag. We describe our rigorous methods for identifying these galaxies, involving the use of Lyman-break strength, detection significance criteria, visual inspection, and integrated photometric redshift probability distributions predominately at high redshift. Our sample is a robust and highly pure collection of distant galaxies from which we also remove brown dwarf stars, and calculate completeness and contamination from simulations. We include a summary of the basic properties of these z > 6.5 galaxies, including their redshift distributions, UV absolute magnitudes, and star formation rates. Our study of these young galaxies reveals a wide range of stellar population properties as seen in their colors and SED fits, which we compare to stellar population models, indicating a range of star formation histories (SFHs), dust, active galactic nuceli, and/or nebular emission. We find that a strong trend exists between stellar mass and ( U − V ) color, as well as the existence of the “main-sequence” of star formation for galaxies as early as z ∼ 12. This indicates that stellar mass, or an underlying variable correlating with stellar mass, is driving galaxy formation, in agreement with simulation predictions. We also discover ultra-high-redshift candidates at z > 12 in our sample and describe their properties. Finally, we note a significant observed excess of galaxies compared to models at z > 12, revealing a tension between predictions and our observations.

We present a detailed investigation into the abundance and morphology of high-redshift quenched galaxies at 3 < z < 7 using James Webb Space Telescope data in the NEP, CEERS, and JADES fields. Within these fields, we identify 90 candidate passive galaxies using specific star formation rates modelled with the BAGPIPES spectral energy distribution fitting code, which is more effective at identifying recently quenched systems than the classical UVJ method, which specializes in quenched objects > 1 Gyr. With this sample of galaxies, we find number densities broadly consistent with other works and a rapidly evolving passive fraction of high-mass galaxies log(10)(M-star/M-circle dot) > 9.5 in the range 3 < z < 5. We find that the fraction of galaxies with low star formation rates and mass 9.5 < log(10)(M-star/M-circle dot) < 10.5 decreases from similar to 25 percent at 3 < z < 4 to similar to 2 percent at 5 < z < 7. Our passive sample of galaxies is shown to exhibit more compact light profiles compared to star-forming counterparts, and some exhibit traces of active galactic nucleus activity through detections in either the X- ray or radio. At the highest redshifts (z > 6.5) passive selections start to include examples of 'little red dots', which complicates any conclusions until their nature is better understood.

We present an analysis of the ultraviolet luminosity function (UV LF) and star formation rate density of distant galaxies (7.5 < z < 13.5) in the “blank” fields of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) survey combined with Early Release Science data from the CEERS, GLASS, and NGDEEP surveys/fields and the first data release of JADES. We use strict quality cuts on EAZY photometric redshifts to obtain a reliable selection and characterization of high-redshift ( z > 6.5) galaxies from a consistently processed set of deep, near-infrared imaging. Within an area of 180 arcmin 2 , we identify 1046 candidate galaxies at redshifts z > 6.5 and we use this sample to study the UV LF in four redshift bins between 7.5 < z < 13.5. The measured number density of galaxies at z = 8 and z = 9 matches those of past observations undertaken by the Hubble Space Telescope (HST). Our z = 10.5 measurements lie between early James Webb Space Telescope (JWST) results and past HST results, indicating cosmic variance may be the cause of previous high density measurements. However, the number densities of UV-luminous galaxies at z = 12.5 are high compared to predictions from simulations. When examining the star formation rate density of galaxies at this period, our observations are still largely consistent with a constant star formation efficiency, are slightly lower than previous early estimations using JWST, and support galaxy driven reionization at z ≤ 8.

The presence of evolved stars in high-redshift galaxies can place valuable indirect constraints on the onset of star formation in the Universe. Thus, we use PEARLS GTO (Prime Extragalactic Areas for Reionization and Lensing Science Guaranteed Time Observations) and public NIRCam (Near Infrared Camera) photometric data to search for Balmer-break candidate galaxies at 7 < z < 12. We find that our Balmer-break candidates at z similar to 10.5 tend to be older (115 Myr), have lower inferred [O III] + H beta equivalent widths (120 angstrom), have lower specific star formation rates (6 Gyr(-1)) and redder UV slopes (beta= -1.8) than our control sample of galaxies. However, these trends all become less strong at z similar to 8, where the F444W filter now probes the strong rest-frame optical emission lines, thus providing additional constraints on the current star formation activity of these galaxies. Indeed, the bursty nature of epoch of reionization galaxies can lead to a disconnect between their current spectral energy distribution (SED) profiles and their more extended star formation histories. We discuss how strong emission lines, the cumulative effect of weak emission lines, dusty continua, and active galactic nuclei can all contribute to the photometric excess seen in the rest-frame optical, thus mimicking the signature of a Balmer break. Additional medium-band imaging will thus be essential to more robustly identify Balmer-break galaxies. However, the Balmer break alone cannot serve as a definitive proxy for the stellar age of galaxies, being complexly dependent on the star formation history. Ultimately, deep Near Infrared Spectrograph (NIRSpec) continuum spectroscopy and Mid-Infrared Instrument (MIRI) imaging will provide the strongest indirect constraints on the formation era of the first galaxies in the Universe, thereby revealing when cosmic dawn breaks.

We present the analysis of the stellar population and star formation history of 181 MIRI selected galaxies at redshift 0-3.5 in the massive galaxy cluster field SMACS J0723.3-7327, commonly referred to as SMACS0723, using the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). We combine the data with the JWST Near Infrared Camera (NIRCam) catalogue, in conjunction with the Hubble Space Telescope (HST) WFC3/IR and ACS imaging. We find that the MIRI bands capture PAH features and dust emission, significantly enhancing the accuracy of photometric redshift and measurements of the physical properties of these galaxies. The median photo-z's of galaxies with MIRI data are found to have a small 0.1% difference from spectroscopic redshifts and reducing the error by 20 percent. With MIRI data included in SED fits, we find that the measured stellar masses are unchanged, while the star formation rate is systematically lower by 0.1 dex. We also fit the median SED of active galactic nuclei (AGN) and star forming galaxies (SFG) separately. MIRI data provides tighter constraints on the AGN contribution, reducing the typical AGN contributions by ~14 percent. In addition, we also compare the median SED obtained with and without MIRI, and we find that including MIRI data yields steeper optical and UV slopes, indicating bluer colours, lower dust attenuation, and younger stellar populations. In the future, MIRI/MRS will enhance our understanding by providing more detailed spectral information and allowing for the study of specific emission features and diagnostics associated with AGN.

We present an analysis of the quenching of star formation in massive galaxies ( M _* > 10 ^9.5 M _⊙ ) within the first 0.5–3 Gyr of the Universe’s history utilizing JWST-CEERS data. We utilize a combination of advanced statistical methods to accurately constrain the intrinsic dependence of quenching in a multidimensional and intercorrelated parameter space. Specifically, we apply random forest classification, area statistics, and a partial correlation analysis to the JWST-CEERS data. First, we identify the key testable predictions from two state-of-the-art cosmological simulations ( IllustrisTNG and EAGLE ). Both simulations predict that quenching should be regulated by supermassive black hole mass in the early Universe. Furthermore, both simulations identify the stellar potential ( ϕ _* ) as the optimal proxy for black hole mass in photometric data. In photometric observations, where we have no direct constraints on black hole masses, we find that the stellar potential is the most predictive parameter of massive galaxy quenching at all epochs from z = 0–8, exactly as predicted by simulations for this sample. The stellar potential outperforms stellar mass, galaxy size, galaxy density, and Sérsic index as a predictor of quiescence at all epochs probed in JWST-CEERS. Collectively, these results strongly imply a stable quenching mechanism operating throughout cosmic history, which is closely connected to the central gravitational potential in galaxies. This connection is explained in cosmological models via massive black holes forming and growing in deep potential wells, and subsequently quenching galaxies through a mix of ejective and preventative active galactic nucleus feedback.

We measure the broad impact of galaxy structure on galaxy formation by examining the ongoing star formation and integrated star formation history as revealed through the stellar masses of galaxies at z < 7 based on JWST CEERS data from the Extended Groth Strip (EGS). Using the morphological catalog of 3965 visually classified JWST galaxies from Ferreira et al. (2023), we investigate the evolution of stars, and when they form, as a function of morphological type as well as galaxies classified as passive and starburst through spectral energy distributions. Although disc galaxies dominate the structures of galaxies at z < 7, we find that these discs are in general either 'passive', or on the main sequence of star formation, and do not contain a large population of starburst galaxies. We also find no significant correlation between morphological type and the star formation rate or colours of galaxies at z < 7. In fact, we find that the morphologically classified 'spheroids' tend to be blue and are not found to be predominately passive systems at z > 1.5. We also find that the stellar mass function for disc galaxies does not evolve significantly during this time, whereas other galaxy types, such as the peculiar population, evolve dramatically, declining at lower redshifts. This indicates that massive peculiars are more common at higher redshifts. We further find that up to z similar to 7, the specific star formation rate (sSFR) does not vary with visual morphology, but strongly depends on stellar mass and internal galaxy mass density. This demonstrates that at early epochs galaxy assembly is a mass-driven, rather than a morphologically driven process. Quenching of star formation is therefore a mass-dominated process throughout the universe's history, likely due to the presence of supermassive black holes.

Galaxy morphologies provide valuable insights into their formation processes, tracing the spatial distribution of ongoing star formation and encoding signatures of dynamical interactions. While such information has been extensively investigated at low redshift, it is crucial to develop a robust system for characterising galaxy morphologies at earlier cosmic epochs. Relying solely on the nomenclature established for low-redshift galaxies risks introducing biases that hinder our understanding of this new regime. In this paper, we employ variational auto-encoders to perform feature extraction on galaxies at z $>$ 2 using JWST/NIRCam data. Our sample comprises 6869 galaxies at z $>$ 2, including 255 galaxies z $>$ 5, which have been detected in both the CANDELS/HST fields and CEERS/JWST, ensuring reliable measurements of redshift, mass, and star formation rates. To address potential biases, we eliminate galaxy orientation and background sources prior to encoding the galaxy features, thereby constructing a physically meaningful feature space. We identify 11 distinct morphological classes that exhibit clear separation in various structural parameters, such as CAS-$M_{20}$, S\'ersic indices, specific star formation rates, and axis ratios. We observe a decline in the presence of spheroidal-type galaxies with increasing redshift, indicating a dominance of disk-like galaxies in the early universe. We demonstrate that conventional visual classification systems are inadequate for high-redshift morphology classification and advocate the need for a more detailed and refined classification scheme. Leveraging machine-extracted features, we propose a solution to this challenge and illustrate how our extracted clusters align with measured parameters, offering greater physical relevance compared to traditional methods.

ABSTRACT We present the results of a size and structural analysis of 1395 galaxies at 0.5 ≤ z ≲ 8 with stellar masses log (M*/M⊙)> 9.5 within the James Webb Space Telescope Public CEERS field that overlaps with the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey EGS observations. We use GALFIT to fit single Sérsic models to the rest-frame optical profile of our galaxies, which is a mass-selected sample complete to our redshift and mass limit. Our primary result is that at fixed rest-frame wavelength and stellar mass, galaxies get progressively smaller, evolving as ∼(1 + z)−0.71 ± 0.19 up to z ∼ 8. We discover that the vast majority of massive galaxies at high redshifts have low Sérsic indices, thus do not contain steep, concentrated light profiles. Additionally, we explore the evolution of the size–stellar mass relationship, finding a correlation such that more massive systems are larger up to z ∼ 3. This relationship breaks down at z > 3, where we find that galaxies are of similar sizes, regardless of their star formation rates and Sérsic index, varying little with mass. We show that galaxies are more compact at redder wavelengths, independent of sSFR or stellar mass up to z ∼ 3. We demonstrate the size evolution of galaxies continues up to z ∼ 8, showing that the process or causes for this evolution is active at early times. We discuss these results in terms of ideas behind galaxy formation and evolution at early epochs, such as their importance in tracing processes driving size evolution, including minor mergers and active galactic nuclei activity.

ABSTRACT In this paper, we discuss measurements of the stellar population and star-forming properties for 43 spectroscopically confirmed publicly available high-redshift z > 7 JWST galaxies in the JADES and CEERS observational programs. We carry out a thorough study investigating the relationship between spectroscopic features and photometrically derived ones, including from spectral energy distribution (SED) fitting of models, as well as morphological and structural properties. We find that the star formation rates (SFRs) measured from H β line emission are higher than those estimated from Bayesian SED fitting and ultraviolet (UV) luminosity, with ratios SFRH β/SFRUV ranging from ∼2 to 13. This is a sign that the star formation history is consistently rising given the time-scales of H β versus UV star formation probes. In addition, we investigate how well equivalent widths (EWs) of H β λ4861, [O iii] λ4959, and [O iii] λ5007 can be measured from photometry, finding that, on average, the EW derived from photometric excesses in filters is 30 per cent smaller than the direct spectroscopic measurement. We also discover that a stack of the line emitting galaxies shows a distinct morphology after subtracting imaging that contains only the continuum. This gives us a first view of the line or ionized gas emission from z > 7 galaxies, demonstrating that this material has a similar distribution, statistically, as the continuum. We also compare the derived SFRs and stellar masses for both parametric and non-parametric star formation histories, where we find that 35 per cent of our sample formed at least 30 per cent of their stellar mass in recent (<10 Myr) starburst events.

We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (PEARLS) project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift protoclusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. Five fields—the JWST NEP Time-Domain Field (TDF), IRAC Dark Field, and three lensing clusters—will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9–4.5 μ m galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9–4.5 μ m. PEARLS is designed to be of lasting benefit to the community.