COSMOS-Web

COSMOS-Web (PID: 1727) is a 255 hour wide-field Cycle 1 JWST treasury program that maps a contiguous 0.6 deg2 area with deep NIRCam imaging in 4 filters (F115W, F150W, F277W, and F444W) and a non-contiguous 0.2 deg2 area with MIRI in parallel. COSMOS-Web builds on the rich heritage of multiwavelength observations and data products available in the COSMOS field, and will contain about a million galaxies across cosmic time. For more information, see survey Overview Paper or contact the survey PIs: Jeyhan Kartaltepe (jeyhan [at] astro [dot] rit [dot] edu) and Caitlin Casey (cmcasey [at] ucsb [dot] edu).

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COSMOS-Web Primary Science Goals

The design of COSMOS-Web is motivated by three primary science goals:

1. Map Cosmic Reionization

COSMOS-Web will revolutionize our understanding of reionization's spatial distribution, environments, and drivers at early stages by detecting thousands of galaxies in the epoch of reionization (6<z<11) on scales large enough to mitigate cosmic variance.
 
Constraining the physics of reionization requires identifying and characterizing the galaxies that are embedded deep within the predominantly neutral Universe at z > 8. COSMOS-Web will grow the census of Epoch of Reionization (EoR, 6<z<11) galaxies beyond what is currently known pre-JWST by a factor of ~5 and quantify the evolution of the UV luminosity function (UVLF), stellar mass function (SMF), and star formation histories of galaxies across a wide redshift range. The large survey area will capture reionization on scales larger than its expected patchiness, eliminating the effect of cosmic variance, and forge the detection of hundreds of intrinsically bright galaxies at 8<z<11 embedded in the neutral IGM, which likely trace the highest-density peaks from which the reionization process was likely to begin.
 

2. Trace Massive Galaxy Evolution

COSMOS-Web will enable the identification and characterization of massive galaxies in the first two billion years, including the rarest quiescent galaxies at z > 4, and allow us to constrain the formation and evolution of early massive galaxies. 
 
The growing census of quiescent galaxies at early epochs (M* > 1010 M⊙ out to z ~ 3–4) has presented a strong challenge to theoretical models. In order to build up their significant stellar masses and quench their star formation so early in the Universe’s history, these galaxies must have formed their stars at incredible rates (≫100 M⊙ yr−1 at very early times) and then abruptly shut down the production of stars well within the Universe’s first billion years. The quiescent galaxy luminosity function beyond z ~ 4 is unconstrained, though such galaxies are expected to be very rare and particularly difficult to separate from dusty star forming galaxies that can mimic the same red colors. COSMOS-Web will allow us to take the first census of massive galaxies from EoR to the peak of galaxy assembly, study the evolution of their morphologies and sizes, and distinguish between massive star-forming galaxies and the first massive quiescent systems. 
 

3. Link Dark Matter to Visible Matter

We will be able to directly measure the evolution of the stellar mass to halo mass relation (SMHR) out to z ~ 2.5 and its variance with galaxies' star formation histories and morphologies. 
 
The link between galaxies’ dark matter halos and their baryonic content (visible matter) is of fundamental importance to cosmology. It is thought that galaxies’ halo mass growth should be independent of their baryonic processes (such as star formation and quenching) and if measurable, could provide a direct path to constraining galaxy growth and quenching mechanisms. Obtaining direct measurements of halo masses not only helps us to constrain the astrophysics of galaxies but also provides independent measurements of cosmological parameters. Weak gravitational lensing is the only tool that can be used as a direct probe of halo masses for a large sample of galaxies across cosmic time. COSMOS-Web will enable these weak lensing measurements, allowing us to directly measure galaxies’ halo masses (and therefore, constrain the SMHR) out to z ~ 2.5 down to M* > few ×109 M⊙ with weak lensing (down to 108 M⊙ at z ~ 1).
 
Beyond these primary science driver’s, COSMOS-Web’s legacy value will extend to many subfields of extragalactic astronomy and beyond. We anticipate that COSMOS-Web will have potential impact on the detailed study of galaxy morphologies, using spatially resolved SEDs to measure galaxy properties, placing constraints on the dust attenuation law, identifying and characterizing galaxy protoclusters, finding strong gravitational lenses, identifying direct collapse black hole candidates, studying the co-evolution of supermassive black holes and their host galaxies, searching for z > 10 pair instability supernovae, and identifying ultracool sub-dwarf stars in the Milky Way’s halo.

 

Observing Strategy

The COSMOS-Web mosaic consists of 152 visits over 255 hours and will be taken over three epochs. The first epoch of data consists of six visits covering ∼77 arcmin2 with NIRCam and was observed on 5-6 January 2023. Currently, 77 pointings are scheduled for April/May 2023 (roughly half the field), and the remaining 69 pointings in December 2023/January 2024. 
 
NIRCam Epoch 1 OverviewThe first epoch of COSMOS-Web NIRCam observations obtained on Jan. 5-6, 2023, including the F115W, F150W, F277W, and F444W filters as a color composite. These data cover six out of a total of 152 visits. The total area covered is ∼77 square arcmin. The relative position of this mosaic in the survey is shown at upper left. At lower left are several zoomed-in 10′′ × 10′′ cutouts and one 16′′ × 16′′ cutout showing specific galaxies selected from these first data. Image credit: COSMOS-Web / Kartaltepe / Casey / Franco / Larson / RIT / UT Austin / CANDIDE. Full resolution image.
 
COSMOS-Web will obtain near-infrared imaging using the NIRCam instrument in four filters, reaching depths determined by the number of NIRCam exposures at a given position (ranging 1-4 exposures). The four filters include two short wavelength bands, F115W and F150W, and two long wavelength bands, F277W and F444W. 
COSMOS-Web NIRCam depths in each filter

NIRCam
Exposures
[#]

Exposure
Time
[s]

Short
Wavelength
Area
[arcmin2]

F115W
Depth
[5 σ]

F150W
Depth
[5 σ]

Long 
Wavelength
Area
[arcmin2]

F277W
Depth
[5 σ]

F444W
Depth
[5 σ]
1 257.68 71.3 26.87 27.14 17.8 27.71 27.61
2 515.36 991.6 27.13 27.35 978.0 27.99 27.83
3 773.05 60.0 27.26 27.50 24.4 28.12 27.94
4 1030.73 805.2 27.45 27.66 904.3 28.28 28.17

 

 
MIRI Epoch 1 OverviewThe first epoch of COSMOS-Web MIRI observations obtained on Jan. 5-6, 2023. The MIRI data are distributed in six non-overlapping tiles and include data from both the MIRI imager and Lyot Coronograph field of view. At left is a comparison between Spitzer IRAC channel 4 (8μm) data and MIRI 7.7μm data in a 40′′ × 40′′ zoom-in panel. Image credit: COSMOS-Web / Kartaltepe / Casey / Harish / Liu / RIT / UT Austin / CANDIDE. Full resolution image.
 
COSMOS-Web will obtain mid-infrared imaging using the MIRI instrument in parallel in one filter, F770W. The depth in this filter varies by the number of MIRI exposures at a given position (ranging 2-8 exposures).
 
COSMOS-Web MIRI F770W Depths

MIRI
Exposures
[#]

Exposure
Time
[s]

Area
Covered
[arcmin2]

F770W Depth
[5 σ]
2 527.26 80.5 25.33
4 1054.52 430.4 25.70
6 1581.77 30.8 25.76
8 2109.03 146.1 25.98

 

Community Downloads

Note that the Cycle 1 program, PRIMER (PID: 1837) observes the COSMOS-CANDELS region and is therefore embedded within COSMOS-Web.

 

Data Product Release

 

COSMOS-Web was observed in three epochs (Epoch 1: Jan 5/6, 2023; Epoch 2: April/May 2023; Epoch 3: December 2023 / January 2024).

Our first data was taken in January 2023 - see below for links to jpg images of these first data!
 

NIRCam: Full resolution image with and without logo

MIRI: Full resolution image with and without logo

 

See our data release page for links to all of our data releases!

 

 

Press Releases and News Articles

  1. COSMOS-Web selected as JWST’s largest Cycle 1 program

  2. First images released from James Webb Space Telescope’s largest general observer program

  3. COSMOS-Web Unveils Largest Look Ever Into the Deep Universe

  4. 780,000 galaxies revealed in JWST’s largest science operation

  5. James Webb Space Telescope reveals largest-ever panorama of the early universe

  6. 1.5 TB of James Webb Space Telescope data just hit the internet
  7. Public gains unprecedented access to Webb telescope's vast cosmic survey
  8. Check out this interactive map of the early universe, considered largest ever created

 

Publications from the COSMOS-Web Team

  1. COSMOS-Web: An Overview of the JWST Cosmic Origins Survey, Casey, Kartaltepe et al. 2023, ApJ, 954, 31 [paper summary]
  2. Resolving Galactic-scale Obscuration of X-Ray AGNs at z ≳ 1 with COSMOS-Web, Silverman et al. 2023, ApJL, 951, 41
  3. A Near-Infrared Faint, Far-Infrared-Luminous Dusty Galaxy at z~5 in COSMOS-Web, McKinney et al. 2023, ApJ, 956, 72
  4. Two massive, compact, and dust-obscured candidate z~8 galaxies discovered by JWST, Akins et al. 2023, ApJL, 956, 61
  5. Uncovering a Massive z 7.7 Galaxy Hosting a Heavily Obscured Radio-loud Active Galactic Nucleus Candidate in COSMOS-Web, Lambrides et al. 2024, ApJL, 961, 25
  6. Unveiling the distant Universe: Characterizing z≥9 Galaxies in the first epoch of COSMOS-Web, Franco et al. 2024, ApJ, 973, 23
  7. Insights into Galaxy Morphology and Star Formation: Unveiling Filamentary Structures around an Extreme Overdensity at z ∼ 1.5 Traced by [O II] Emitters, Laishram et al. 2024, ApJL, 964, 33
  8. COSMOS-Web: Intrinsically Luminous z ≳ 10 Galaxy Candidates Test Early Stellar Mass Assembly, Casey et al. 2024, ApJ, 965, 98
  9. Tracing the rise of supermassive black holes. A panchromatic search for faint, unobscured quasars at z ≳ 6 with COSMOS-Web and other surveys, Andika et al. 2024, A&A, 685, 25
  10. JWST and ALMA Discern the Assembly of Structural and Obscured Components in a High-redshift Starburst Galaxy, Liu et al. 2024, ApJ, 968, 15
  11. COSMOS-Web: The over-abundance and physical nature of "little red dots"--Implications for early galaxy and SMBH assembly, Akins et al. 2024, ApJ, submitted
  12. The COSMOS-Web ring: In-depth characterization of an Einstein ring lensing system at z ∼ 2, Mercier et al. 2024, A&A, 687, 61
  13. The Web Epoch of Reionization Lyα Survey (WERLS). I. MOSFIRE Spectroscopy of z ∼ 7–8 Lyα Emitters, Cooper et al. 2024, ApJ, 970, 50
  14. Not-so-little Red Dots: Two Massive and Dusty Starbursts at z ∼ 5–7 Pushing the Limits of Star Formation Discovered by JWST in the COSMOS-Web Survey, Gentile et al. 2024, ApJ, 973, 2
  15. Efficient Point-spread Function Modeling with ShOpt.jl: A Point-spread Function Benchmarking Study with JWST NIRCam Imaging, Berman et al. 2024, AJ, 168, 174
  16. Crimson Behemoth: A massive clumpy structure hosting a dusty AGN at z=4.91, Tanaka et al. 2024, PASJ, 76, 1323
  17. Discovery of dual "little red dots" indicates excess clustering on kilo-parsec scales, Tanaka et al. 2024, PASJ, submitted
  18. Clumps as multiscale structures in cosmic noon galaxies, Kalita et al. 2025, MNRAS, 536, 3090
  19. Tracing the galaxy-halo connection with galaxy clustering in COSMOS-Web from z = 0.1 to z ~ 12, Paquereau et al. 2025, A&A, submitted
  20. The MBH–M∗ Relation up to z ∼ 2 through Decomposition of COSMOS-Web NIRCam Images, Tanaka et al. 2025, ApJ, 979, 215
  21. SCUBADive. I. JWST+ALMA Analysis of 289 Submillimeter Galaxies in COSMOS-Web, McKinney et al. 2025, ApJ, 979, 229
  22. A Multiwavelength Investigation of Spiral Structures in z > 1 Galaxies with JWST, Kalita et al. 2025, ApJ, 979L, 44
  23. COSMOS-Web: The Role of Galaxy Interactions and Disk Instabilities in Producing Starbursts at z < 4, Faisst et al. 2025, ApJ, 980, 204
  24. COSMOS-Web: The emergence of the Hubble Sequence, Huertas-Company et al. 2025, A&A, submitted
  25. Tracing High-z Galaxies in X-rays with JWST and Chandra, Kaminsky et al. 2025, ApJ, in press
  26. COSMOS-Web: Stellar mass assembly in relation to dark matter halos across 0.2 < z < 12 of cosmic history, Shuntov et al. 2025, A&A, 695, 20
  27. Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z > 2 with JWST, Pierel et al. 2025, ApJL, 981, 9
  28. The COSMOS-Web Lens Survey (COWLS) I: Discovery of >100 high redshift strong lenses in contiguous JWST imaging, Nightingale et al. 2025, MNRAS, submitted
  29. The COSMOS-Web Lens Survey (COWLS) II: depth, resolution, and NIR coverage from JWST reveal 17 spectacular lenses, Mahler et al. 2025, MNRAS, submitted
  30. The COSMOS-Web Lens Survey (COWLS) III: forecasts versus data, Hogg et al. 2025, MNRAS, submitted
  31. COSMOS-Web: A history of galaxy migrations over the stellar mass–star formation rate plane, Arango-Toro et al. 2025, A&A, 696, 159
  32. The COSMOS-Web ring: Spectroscopic confirmation of the background source at z = 5.1, Shuntov et al. 2025, A&A, 696, 14
  33. On Soft Clustering For Correlation Estimators: Model Uncertainty, Differentiability, and Surrogates, Berman et al. 2025, OjA, submitted
  34. COSMOS-Web: Unraveling the Evolution of Galaxy Size and Related Properties at  2<z<10, Yang et al. 2025, ApJ, submitted
  35. JWST Discovery of a High-Redshift Tidal Disruption Event Candidate in COSMOS-Web, Karmen et al. 2025, ApJ, submitted
  36. Going deeper into the dark with COSMOS-Web: JWST unveils the total contribution of radio-selected NIR-faint galaxies to the cosmic star formation rate density, Gentile et al. 2025, A&A, 679, 46
  37. The COSMOS-Web deep galaxy group catalog up to z = 3.7, Toni et al. 2025, A&A, 697, 197
  38. SCUBADive II: Searching for  z>4 Dust-Obscured Galaxies via F150W-Dropouts in COSMOS-Web, Manning et al. 2025, ApJ, submitted
  39. COSMOS-Web: MIRI Data Reduction and Number Counts at 7.7μm using JWST, Harish et al. 2025, ApJ, submitted
  40. COSMOS-Web: Comprehensive Data Reduction for Wide-Area JWST NIRCam Imaging, Franco et al. 2025, ApJ, submitted
  41. COSMOS2025: The COSMOS-Web Galaxy Catalog of Photometry, Morphology, Redshifts, and Physical Parameters from JWST, HST, and Ground-based Imaging, Shuntov et al. 2025, A&A, submitted [paper summary]
  42. Brightest Group Galaxies IV: Probing Size–mass Relation and Morphological Quenching in COSMOS-Web from z = 3.7, Gozalisal et al. 2025, A&A, submitted
  43. COSMOS-Web: Estimating Physical Parameters of Galaxies Using Self-Organizing Maps, Abedini et al. 2025, A&A, submitted
  44. Clumpiness of galaxies revealed in the near-infrared with COSMOS-Web, Mercier et al. 2025, A&A, submitted

 

Publications from the COSMOS-3D Team

  1. Bridging Quasars and Little Red Dots: Insights into Broad-Line AGNs at  z=5−8 from the First JWST COSMOS-3D Dataset, Lin et al. 2025, ApJ, submitted
  2. The Cosmic Owl: Twin Active Collisional Ring Galaxies with Starburst Merging Front at z=1.14, Li et al. 2025, ApJ, submitted

 

Publications from members of the community

  1. Seeking the growth of the first black hole seeds with JWST, Trinca et al. 2023, MNRAS, 519, 4753
  2. On the detectability of strong lensing in near-infrared surveys, Holloway et al. 2023, MNRAS, 525, 2341
  3. JWST Confirms the Nature of CID-42, Li, Zhuang, & Shen 2024, ApJ, 961, 19
  4. A massive compact quiescent galaxy at z = 2 with a complete Einstein ring in JWST imaging, van Dokkum et al. 2024, NatAs, 8, 119
  5. Active Galactic Nuclei and Host Galaxies in COSMOS-Web. I. NIRCam Images, Point-spread-function Models and Initial Results on X-Ray-selected Broad-line AGNs at 0.35 ≲ z ≲ 3.5,  Zhuang, Li, & Shen 2024, ApJ, 962, 93
  6. Unveiling Luminous Lyα Emitters at z ≈ 6 through JWST/NIRCam Imaging in the COSMOS Field, Ning et al. 2024, ApJL, 963, 38
  7. A Radio Galaxy Gravitational Lens in the COSMOS-Web Survey, Moore & Lacy, RNAAS, 8, 62
  8. Active Galactic Nuclei and Host Galaxies in COSMOS-Web. II. First Look at the Kpc-scale Dual and Offset AGN Population, Li et al. 2024, ApJ, submitted
  9. JWST's First Glimpse of a z > 2 Forming Cluster Reveals a Top-heavy Stellar Mass Function, Sun et al. 2024, ApJL, 967, 34
  10. The Size–Mass Relation at Rest-frame 1.5 μm from JWST/NIRCam in the COSMOS-Web and PRIMER-COSMOS Fields, Moartorano et al. 2024, 972, 134
  11. Sub-Eddington accreting supermassive primordial black holes explain Little Red Dots, Huang et al. 2024, MNRAS, submitted
  12. Brown dwarf number density in the JWST COSMOS-Web field, Chen et al. 2025, PASA, 42,42
  13. Evolution of the Sérsic index up to z = 2.5 from JWST and HST, Martorano et al. 2025, A&A, 649, 76
  14. JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at z ∼ 7–14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe, Harikane et al. 2025, ApJ, 980, 138
  15. Dual-coding Contrastive Learning Based on the ConvNeXt and ViT Models for Morphological Classification of Galaxies in COSMOS-Web, Zhu et al. 2025, ApJS, 278, 39
  16. Unveiling a Population of Strong Galaxy-Galaxy Lensed Faint Dusty Star-Forming Galaxies, Yang et al. 2025, ApJL, submitted
  17. The Infinity Galaxy: a Candidate Direct-Collapse Supermassive Black Hole Between Two Massive, Ringed Nuclei, van Dokkum et al. 2025, ApJL, submitted
  18. Further Evidence for a Direct-Collapse Origin of the Supermassive Black Hole at the Center of the Infinity Galaxy, van Dokkum et al., 2025, ApJL, submitted
  19. Even Redder than we Knew: Color and  A_V Evolution up to  z=2.5 from JWST/NIRCam Photometry, van der Wel et al., 2025, A&A, in press