Surveys with James Webb Space Telescope (JWST) have discovered candidate galaxies in the first 400 Myr of cosmic time 1-5 . The properties of these distant galaxies provide initial conditions for understanding early galaxy formation and cosmic reionisation 6 . Preliminary indications have suggested these candidate galaxies may be more massive and abundant than previously thought 1,7-9 . However, without spectroscopic confirmation of their distances to constrain their intrinsic brightnesses, their inferred properties remain uncertain. Here we report on four galaxies located in the JWST Advanced Deep Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam) imaging with photometric redshifts 𝒛 ∼ 𝟏𝟎 − 𝟏𝟑 subsequently confirmed by JADES JWST Near-Infrared Spectrograph (NIRSpec) observations 10 . These galaxies include the first redshift 𝒛 > 𝟏𝟐 systems both discovered and spectroscopically confirmed by JWST. Using stellar population modelling, we find the galaxies typically contain a hundred million solar masses in stars, in stellar populations that are less than one hundred million years old. The moderate star formation rates and compact sizes suggest elevated star formation rate surface densities, a key indicator of their formation pathways. Taken together, these measurements show that the first galaxies contributing to cosmic reionisation formed rapidly and with intense internal radiation fields.

Finding and characterising the first galaxies that illuminated the early Universe at cosmic dawn is pivotal to understand the physical conditions and the processes that led to the formation of the first stars. In the first few months of operations, imaging from the James Webb Space Telescope (JWST) has been used to identify tens of candidates of galaxies at redshift (z) greater than 10 less than 450 million years after the Big Bang. However, none of such candidates has yet been confirmed spectroscopically, leaving open the possibility that they are actually low-redshift interlopers. Here we present spectroscopic confirmation and analysis of four galaxies unambiguously detected at redshift 10.3≤z≤13.2, previously selected from NIRCam imaging. The spectra reveal that these primeval galaxies are metal poor, have masses between of order ~10 7 -10 8 solar masses, and young ages. The damping wings that shape the continuum close to the Lyman edge provide the first constraints on neutral Hydrogen fraction of the intergalactic medium to be obtained from normal star-forming galaxies. These findings demonstrate the rapid emergence of the first generations of galaxies at cosmic dawn.The opening act of galaxy formation in the first billion years after the Big Bang sets in motion the physics of galaxy formation and evolution that shapes galaxy properties across cosmic time. Galaxies forming at these times may be the seeds of the much more massive and mature galaxies in the local Universe. Theoretical models and cosmological simulations differ greatly in their predictions of the physical properties and abundance of the first galaxies. The theoretical pictures depend strongly on assumptions about the physical processes at play in

We present Morpheus, a new model for generating pixel-level morphological classifications of astronomical sources. Morpheus leverages advances in deep learning to perform source detection, source segmentation, and morphological classification pixel-by-pixel via a semantic segmentation algorithm adopted from the field of computer vision. By utilizing morphological information about the flux of real astronomical sources during object detection, Morpheus shows resiliency to false-positive identifications of sources. We evaluate Morpheus by performing source detection, source segmentation, morphological classification on the Hubble Space Telescope data in the five CANDELS fields with a focus on the GOODS South field, and demonstrate a high completeness in recovering known GOODS South 3D-HST sources with H < 26 AB. We release the code publicly, provide online demonstrations, and present an interactive visualization of the Morpheus results in GOODS South.

We present JADES JWST/NIRSpec spectroscopy of GN-z11, the most luminous candidate z > 10 Lyman break galaxy in the GOODS-North field with M UV = −21.5. We derive a redshift of z = 10.603 (lower than previous determinations) based on multiple emission lines in our low and medium resolution spectra over 0.8 − 5.3 µm. We significantly detect the continuum and measure a blue rest-UV spectral slope of β = −2.4. Remarkably, we see spatially-extended Lyman-α in emission (despite the highly-neutral IGM expected at this early epoch), offset 555 km s −1 redward of the systemic redshift. From our measurements of collisionally-excited lines of both low-and high-ionization (including [O ii] λ3727, [Ne iii] λ3869 and C iii] λ1909) we infer a high ionization parameter (log U ∼ −2). We detect the rarely-seen N iv] λ1486 and N iii] λ1748 lines in both our low and medium resolution spectra, with other high ionization lines seen in low resolution spectrum such as He ii (blended with O iii]) and C iv (with a possible P-Cygni profile). Based on the observed rest-UV line ratios, we cannot conclusively rule out photoionization from AGN. The high C iii]/He ii ratios, however, suggest a likely star-formation explanation. If the observed emission lines are powered by star formation, then the strong N iii] λ1748 observed may imply an unusually high N/O abundance. Balmer emission lines (Hγ, Hδ) are also detected, and if powered by star formation rather than an AGN we infer a star formation rate of ∼ 20 − 30 M yr −1 (depending on the IMF) and low dust attenuation. Our NIRSpec spectroscopy confirms that GN-z11 is a remarkable galaxy with extreme properties seen 430 Myr after the Big Bang.

We present JWST NIRCam nine-band near-infrared imaging of the luminous z = 10.6 galaxy GN-z11 from the JWST Advanced Deep Extragalactic Survey of the GOODS-N field. We find a spectral energy distribution (SED) entirely consistent with the expected form of a high-redshift galaxy: a clear blue continuum from 1.5 to 4 μm with a complete dropout in F115W. The core of GN-z11 is extremely compact in JWST imaging. We analyze the image with a two-component model, using a point source and a Sérsic profile that fits to a half-light radius of 200 pc and an index n = 0.9. We find a low-surface-brightness haze about 0.″4 to the northeast of the galaxy, which is most likely a foreground object but might be a more extended component of GN-z11. At a spectroscopic redshift of 10.60 (Bunker et al. 2023), the comparison of the NIRCam F410M and F444W images spans the Balmer jump. From population-synthesis modeling, here assuming no light from an active galactic nucleus, we reproduce the SED of GN-z11, finding a stellar mass of ∼109 M ⊙, a star formation rate of ∼20 M ⊙ yr−1, and a young stellar age of ∼20 Myr. Since massive galaxies at high redshift are likely to be highly clustered, we search for faint neighbors of GN-z11, finding nine galaxies out to ∼5 comoving Mpc transverse with photometric redshifts consistent with z = 10.6, and a tenth more tentative dropout only 3″ away. This is consistent with GN-z11 being hosted by a massive dark-matter halo (≈8 × 1010 M ⊙), though lower halo masses cannot be ruled out.