Explore the vast range of titles available.

Accurately distinguishing between quiescent and star-forming galaxies is essential for understanding galaxy evolution. Traditional methods, such as spectral energy distribution (SED) fitting, can be computationally expensive and may struggle to capture complex galaxy properties. This study aims to develop a robust and efficient machine learning (ML) classification method to identify quiescent and star-forming galaxies within the Farmer COSMOS2020 catalog. We utilized JWST wide-field light cones from the Santa Cruz semianalytical modeling framework to train a supervised ML model, the CatBoostClassifier, using 28 color features derived from eight mutual photometric bands within the COSMOS catalog. The model was validated against a testing set and compared to the SED-fitting method in terms of precision, recall, F1 score, and execution time. Preprocessing steps included addressing missing data, injecting observational noise, and applying a magnitude cut (mch1 < 26 AB) along with a redshift range of 0.2 < z < 3.5 to align the simulated and observational data sets. The ML method achieved an F1 score of 89% for quiescent galaxies, significantly outperforming the SED-fitting method, which achieved 54%. The ML model demonstrated superior recall (88% versus 38%) while maintaining comparable precision. When applied to the COSMOS2020 catalog, the ML model predicted a systematically higher fraction of quiescent galaxies across all redshift bins within 0.2 < z < 3.5 compared to traditional methods like NUVrJ and SED-fitting. This study shows that ML, combined with multiwavelength data, can effectively identify quiescent and star-forming galaxies, providing valuable insights into galaxy evolution. The trained classifier and full classification catalog are publicly available.

Our knowledge of relations between supermassive black holes and their host galaxies at z ≳ 1 is still limited, even though being actively sought out to z ∼ 6. Here, we use the high resolution and sensitivity of JWST to measure the host galaxy properties for 107 X-ray-selected type-I active galactic nuclei (AGNs) at 0.68 < z < 2.5 with rest-frame optical/near-infrared imaging from COSMOS-Web and PRIMER. Black hole masses ( logMBH/M⊙∼6.9−9.6 ) are available from previous spectroscopic campaigns. We extract the host galaxy components from four NIRCam broadband images and the Hubble Space Telescope/Advanced Camera for Surveys F814W image by applying a 2D image decomposition technique. We detect the host galaxy for ∼90% of the sample after subtracting the unresolved AGN emission. With host photometry free of AGN emission, we determine the stellar mass of the host galaxies to be logM*/M⊙∼9.5−11.6 through spectral energy distribution fitting and measure the evolution of the mass relation between SMBHs and their host galaxies. Considering selection biases and measurement uncertainties, we find that the MBH/M*ratio evolves as 1+z0.48−0.62+0.31 thus remains essentially constant or exhibits mild evolution up to z ∼ 2.5. We also see an amount of scatter ( σμ=0.30−0.13+0.14 ), similar to the local relation and consistent with low-z studies, and a noncausal cosmic assembly history where mergers contribute to the statistical averaging toward the local relation is still feasible. We highlight improvements to come with larger samples from JWST and, particularly, Euclid, which will exceed the statistical power of current wide and deep surveys.

JWST has enabled detecting and spatially resolving the heavily dust-attenuated stellar populations of submillimeter galaxies, revealing detail that was previously inaccessible. In this work, we construct a sample of 289 submillimeter galaxies with joint Atacama Large Millimeter/submillimeter Array (ALMA) and JWST constraints in the COSMOS field. Sources are originally selected using the SCUBA-2 instrument and have archival ALMA observations from various programs. Their JWST NIRCam imaging is from COSMOS-Web and PRIMER. We extract multiwavelength photometry in a manner that leverages the unprecedented near-infrared (NIR) spatial resolution of JWST, and we fit the data with spectral energy distribution models to derive photometric redshifts, stellar masses, star formation rates, and optical attenuation. The sample has an average 〈z〉=2.6−0.8+1.0 , 〈AV〉=2.5−1.0+1.5 , 〈SFR〉=300−200+400M⊙yr−1 , and 〈log(M*/M⊙)〉=11.1−0.5+0.3 . There are 81 (30%) galaxies that have no previous optical/NIR detections, including 75% of the z > 4 subsample (n = 28). The faintest observed NIR sources have the highest redshifts and largest AV = 4 ± 1. In a preliminary morphology analysis we find that ∼10% of the members of our sample exhibit spiral arms and 5% host stellar bars, with one candidate bar found at z > 3. Finally, we find that the clustering of JWST sources within 10″ of a submillimeter galaxy is a factor of 2 greater than what is expected based on either random clustering or the distribution of sources around any red galaxy irrespective of a submillimeter detection.

Extreme emission line galaxies (EELGs) are powerful low-z analogs of high-z galaxies that can provide us valuable insights of early Universe conditions. We present a detailed analysis of EELG1002: a z = 0.8275 EELG identified within archival Gemini/GMOS spectroscopy as part of the ongoing COSMOS Spectroscopic Archive. We find EELG1002 is a low-mass (∼108 M⊙), compact (∼530 pc), bursty star-forming galaxy with a ∼15–35 Myr mass doubling timescale. EELG1002 has record-breaking rest-frame [O iii]+Hβ EW ∼3100–3700 Å; ∼32–36× higher than typical z ∼ 0.8 [O iii] emitters with similar stellar mass; and higher than typical z > 5 galaxies. We find no clear evidence of an active galactic nucleus suggesting the emission lines are star formation driven. EELG1002 is chemically unevolved (direct Te; 12+log10(O/H)∼7.52 consistent with z > 5 galaxies at fixed stellar mass) and may be undergoing a first intense, bursty star formation phase analogous to conditions expected of galaxies in the early Universe. We find evidence for a highly energetic interstellar medium ([O iii]/[O ii] ∼ 9) and hard ionizing radiation field (elevated [Ne iii]/[O ii] at fixed [O iii]/[O ii]). Coupled with its compact, metal-poor, and actively star-forming nature, EELG1002 is found to efficiently produce ionizing photons (ξion ∼ 1025.74 erg−1 Hz) and may have ∼10%–20% Lyman Continuum (LyC) escape suggesting such sources may be important analogs of galaxies responsible for reionization. We find a dynamical mass of ∼109 M⊙ suggesting copious amounts of gas to support intense star formation as also suggested by identified Illustris-TNG analogs. EELG1002 may be an ideal low-z laboratory of galaxies in the early Universe and demonstrates how archival data sets can support high-z science and next-generation surveys planned with Euclid and Roman.

We investigate how different galaxy formation models impact the stellar properties of brightest group galaxies (BGGs) in four cosmological simulations: Romulus, Simba, Simba-C, and Obsidian. The stellar masses, specific star formation rates, and mass-weighted stellar ages of the simulated BGGs are analyzed alongside those of observed BGGs from X-ray-selected galaxy groups in the Cosmic Evolution Survey (COSMOS) field. We find that the global properties and underlying evolutionary pathways of simulated BGG populations are strongly impacted by the strength and mechanism of their respective active galactic nucleus (AGN) feedback models, which play a critical role in regulating the growth of massive galaxies. Obsidian’s sophisticated three-regime AGN feedback model achieves the highest overall agreement with COSMOS observations, matching stellar property distributions, quenched fractions, and the evolution of star formation in increasingly massive systems. We find evidence suggesting that BGG populations of Obsidian and COSMOS undergo a gradual decline in star formation with stellar mass, in contrast to Simba and Simba-C, which display rapid quenching linked to the onset of powerful AGN jet feedback. By comparison, Romulus produces highly star-forming, under-quenched BGGs due to the inefficiency of its thermal AGN feedback in preventing cooling flows from fuelling BGG growth. The success of the Obsidian simulation demonstrates the importance of physically motivated subgrid prescriptions for realistically capturing the processes that shape BGGs and their dynamic group environments.

The COSMOS-Web survey is the largest JWST Cycle 1 General Observer program, covering a contiguous ∼0.54 deg2 area with NIRCam imaging in four broadband filters and a noncontiguous ∼0.2 deg2 with parallel MIRI imaging in a single broadband filter, F770W. Here we present a comprehensive overview of the MIRI imaging observations, the data reduction procedure, the COSMOS-Web MIRI photometric catalog, and the first data release including the entire COSMOS-Web MIRI coverage. Data reduction primarily relies on the JWST Science Calibration Pipeline, supplemented by custom background subtraction to mitigate prominent instrumental artifacts and sky background within the MIRI images. We reach 5σ (point source) limiting depths (mF770W ∼ 25.51 based on r ∼ 0 .″ 3 circular apertures) that are significantly better than initial expectations. Using the images provided in this release, we construct a photometric catalog and compare the F770W flux densities to the Spitzer/IRAC CH4 measurements from the COSMOS2020 catalog (for CH4 detections with signal-to-noise ratio S/N > 5). We find that these are in reasonable agreement with a small median offset of <0.05 mag. We also derive robust 7.7 μm number counts spanning five orders of magnitude in flux (∼0.2–2300 μJy)—making COSMOS-Web the only JWST survey to date to sample such a large flux range—which are in good agreement with estimates from other JWST and IRAC surveys.

A growing number of far-infrared (FIR) bright sources completely invisible in deep extragalactic optical surveys hint at an elusive population of z > 4 dusty, star-forming galaxies. Cycle 1 JWST surveys are now detecting their rest-frame optical light, which provides key insight into their stellar properties and statistical constraints on the population as a whole. This work presents the JWST Near Infrared Camera (NIRCam) counterpart from the COSMOS-Web survey to an FIR SCUBA-2 and Atacama Large Millimeter/submillimeter Array (ALMA) source, AzTECC71, which was previously undetected at wavelengths shorter than 850 μm. AzTECC71, among the reddest galaxies in COSMOS-Web with F277W − F444W ∼ 0.9, is undetected in NIRCam/F150W and F115W and fainter in F444W than other submillimeter galaxies identified in COSMOS-Web by 2–4 magnitudes. This is consistent with the system having both a lower stellar mass and higher redshift than the median dusty, star-forming galaxy. With deep ground- and space-based upper limits combined with detections in F277W, F444W, and the FIR including ALMA Band 6, we find a high probability (99%) that AzTECC71 is at z > 4 with zphot=5.7−0.7+0.8 . This galaxy is massive ( logM*/M⊙∼10.7 ) and infrared-luminous ( logLIR/L⊙∼12.7 ), comparable to other optically undetected but FIR-bright dusty, star-forming galaxies at z > 4. This population of luminous, infrared galaxies at z > 4 is largely unconstrained but comprises an important bridge between the most extreme dust-obscured galaxies and more typical high-redshift star-forming galaxies. If further FIR-selected galaxies that drop out of the F150W filter in COSMOS-Web have redshifts z > 4 like AzTECC71, then the volume density of such sources may be ∼3–10 × greater than previously estimated.

We present observations and analysis of the starburst PACS-819 at z = 1.45 (M * = 1010.7 M ⊙), using high-resolution (0.″1; 0.8 kpc) Atacama Large Millimeter/submillimeter Array (ALMA) and multiwavelength JWST images from the COSMOS-Web program. Dissimilar to Hubble Space Telescope (HST) ACS images in the rest-frame UV, the redder NIRCam and MIRI images reveal a smooth central mass concentration and spiral-like features, atypical for such an intense starburst. Through dynamical modeling of the CO (J = 5–4) emission with ALMA, PACS-819 is rotation dominated and thus consistent with having a disk-like nature. However, kinematic anomalies in CO and asymmetric features in the bluer JWST bands (e.g., F150W) support a more disturbed nature likely due to interactions. The JWST imaging further enables us to map the distribution of stellar mass and dust attenuation, thus clarifying the relationships between different structural components not discernible in the previous HST images. The CO (J = 5–4) and far-infrared dust continuum emission are cospatial with a heavily obscured starbursting core (<1 kpc) that is partially surrounded by much less obscured star-forming structures including a prominent arc, possibly a tidally distorted dwarf galaxy, and a massive clump (detected in CO), likely a recently accreted low-mass satellite. With spatially resolved maps, we find a high molecular gas fraction in the central area reaching ∼3 (M gas/M *) and short depletion times (M gas/SFR ∼ 120 Myr, where SFR is star formation rate) across the entire system. These observations provide insights into the complex nature of starbursts in the distant Universe and underscore the wealth of complementary information from high-resolution observations with both ALMA and JWST.

We measure galaxy sizes from 2 < z < 10 using COSMOS-Web, the largest-area JWST imaging survey to date, covering ∼0.54 deg2. We analyze the rest-frame optical (∼5000 Å) size evolution and its scaling relation with stellar mass ( Re∝M*α ) for star-forming and quiescent galaxies. For star-forming galaxies, the slope α remains approximately 0.20 at 2 < z < 8, showing no significant evolution over this redshift range. At higher redshifts, the slopes are −0.13 ± 0.15 and 0.37 ± 0.36 for 8 < z < 9 and 9 < z < 10, respectively. At fixed galaxy mass, the size evolution for star-forming galaxies follows Re ∝ (1 + z)−1.21±0.05. For quiescent galaxies, the size–mass relation is steeper with α ∼ 0.5–0.8 at 2 < z < 5, and size evolves as Re ∝ (1 + z)−0.81±0.26. We find that the size−mass relation is consistent between UV and optical at z < 8 for star-forming galaxies. However, we observe a decrease in the slope from UV to optical at z > 8, with a tentative negative slope in the optical at 8 < z < 9, suggesting a complex interplay between intrinsic galaxy properties and observational effects such as dust attenuation. We discuss the ratio between galaxies’ half-light radius and underlying halos’ virial radius, Rvir, and find the median value of Re/Rvir = 2.7%. The star formation rate surface density evolves as log(ΣSFR/(M⊙/yr/kpc2))= (0.20 ± 0.08)z + (−0.65 ± 0.51), and the ΣSFR–M* relation remains flat at 2 < z < 10. Lastly, we identify a threshold in stellar mass surface density log(Σe/(M⊙/kpc2))∼9.5−10 marking the transition to compact, quenched galaxies from extended, star-forming progenitors. In summary, our findings show that the extensive COSMOS-Web dataset at z > 3 provides new insights into galaxy size and related properties in the rest-frame optical.

The role of internal and environmental factors in the star formation activity of galaxies is still a matter of debate, in particular at higher redshifts. Leveraging the most recent release of the COSMOS catalog, COSMOS2020, as well as density measurements from our previous study, we disentangle the impact of environment and stellar mass on the star formation rate (SFR) and specific SFR (sSFR) of a sample of ∼210,000 galaxies within a redshift range of 0.4 < z < 4, and present our findings in three cosmic epochs: (1) out to z ∼ 1, the average SFR and sSFR decline in extremely dense environments and at the high-mass end of the distribution, which is mostly due to the presence of the massive quiescent population; (2) at 1 < z < 2, the environmental dependence diminishes, while mass is still the dominant factor in star formation activity; and (3) beyond z ∼ 2, our sample is dominated by star-forming galaxies and we observe a reversal of the trends seen in the local Universe—the average SFR increases with increasing environmental density. Our analysis shows that both environmental and mass quenching efficiencies increase with stellar mass at all redshifts, with mass being the dominant quenching factor in massive galaxies compared to environmental effects. At 2 < z < 4, negative values of environmental quenching efficiency suggest that the fraction of star-forming galaxies in dense environments exceeds that in less-dense regions, likely due to the greater availability of cold gas, higher merger rates, and tidal effects that trigger star formation activity.