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Early observations with JWST have led to the discovery of an unexpectedly large density (stellar-mass density ρ * ≈ 106 M ⊙ Mpc−3) of massive galaxies (stellar masses M * ≥ 1010.5 M ⊙) at extremely high redshifts z ≈ 10. While such a result is based on early measurements that are still affected by uncertainties currently under consideration by several observational groups, its confirmation would have a strong impact on cosmology. Here we show that—under the most conservative assumptions and independently of the baryon physics involved in galaxy formation—such galaxy abundance is not only in tension with the standard ΛCDM cosmology but provides extremely tight constraints on the expansion history of the universe and on the growth factors corresponding to a wide class of Dynamical Dark Energy (DDE) models. Adopting a parameterization w = w 0 + w a (1 − a) for the evolution of the DDE equation of the state parameter w with the expansion factor a, we derive constraints on combinations of (w 0, w a ) that rule out with confidence level >2σ a major portion of the parameter space (w 0, w a ) allowed (or even favored) by existing cosmological probes.

Star-forming galaxies can exhibit strong morphological differences between the rest-frame far-UV and optical, reflecting inhomogeneities in star formation and dust attenuation. We exploit deep, high-resolution, NIRCAM seven-band observations to take a first look at the morphology of galaxies in the epoch of reionization (z > 7), and its variation in the rest-frame wavelength range between Lyα and 6000–4000 Å, at z = 7–12. We find no dramatic variations in morphology with wavelength—of the kind that would have overturned anything we have learned from the Hubble Space Telescope. No significant trends between morphology and wavelengths are detected using standard quantitative morphology statistics. We detect signatures of mergers/interactions in 4/19 galaxies. Our results are consistent with a scenario in which Lyman-break galaxies—observed when the universe is only 400–800 Myr old—are growing via a combination of rapid, galaxy-scale star formation supplemented by the accretion of star-forming clumps and interactions.

We exploit James Webb Space Telescope (JWST) NIRCam observations from the GLASS-JWST-Early Release Science program to investigate galaxy stellar masses at z > 7. We first show that JWST observations reduce the uncertainties on the stellar mass by a factor of at least 5–10, when compared with the highest-quality data sets available to date. We then study the UV mass-to-light ratio, finding that galaxies exhibit a a two orders of magnitude range of M/L UV values for a given luminosity, indicative of a broad variety of physical conditions and star formation histories. As a consequence, previous estimates of the cosmic stellar-mass density—based on an average correlation between UV luminosity and stellar mass—can be biased by as much as a factor of ∼6. Our first exploration demonstrates that JWST represents a new era in our understanding of stellar masses at z > 7 and, therefore, of the growth of galaxies prior to cosmic reionization.

We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on the James Webb Space Telescope (JWST) as part of the GLASS-JWST Early Release Science program. We select 388 sources at redshifts 0.8 < z < 5.4 and use the seven 0.9–5 μm NIRCam filters to generate rest-frame gri composite color images, and conduct visual morphological classification. Compared to Hubble Space Telescope (HST)–based work we find a higher incidence of disks and bulges than expected at z > 1.5, revealed by rest-frame optical imaging. We detect 123 clear disks (58 at z > 1.5) of which 76 have bulges. No evolution of bulge fraction with redshift is evident: 61% at z < 2 (N = 110) versus 60% at z ≥ 2 (N = 13). A stellar mass dependence is evident, with bulges visible in 80% of all disk galaxies with mass >109.5 M ⊙ (N = 41) but only 52% at M < 109.5 M ⊙ (N = 82). We supplement visual morphologies with nonparametric measurements of Gini and asymmetry coefficients in the rest-frame i band. Our sources are more asymmetric than local galaxies, with slightly higher Gini values. When compared to high-z rest-frame ultraviolet measurements with HST, JWST shows more regular morphological types such as disks, bulges, and spiral arms at z > 1.5, with smoother (i.e., lower Gini) and more symmetrical light distributions.

We present the first James Webb Space Telescope/NIRCam-led determination of 7 < z < 9 galaxy properties based on broadband imaging from 0.8 to 5 μm as part of the GLASS-JWST Early Release Science program. This is the deepest data set acquired at these wavelengths to date, with an angular resolution ≲0.″14. We robustly identify 13 galaxies with signal-to-noise ratio ≳ 8 in F444W from 8 arcmin2 of data at m AB ≤ 28 from a combination of dropout and photometric redshift selection. From simulated data modeling, we estimate the dropout sample purity to be ≳90%. We find that the number density of these F444W-selected sources is broadly consistent with expectations from the UV luminosity function determined from Hubble Space Telescope data. We characterize galaxy physical properties using a Bayesian spectral energy distribution fitting method, finding a median stellar mass of 108.5 M ⊙ and age 140 Myr, indicating they started ionizing their surroundings at redshift z > 9.5. Their star formation main sequence is consistent with predictions from simulations. Lastly, we introduce an analytical framework to constrain main-sequence evolution at z > 7 based on galaxy ages and basic assumptions, through which we find results consistent with expectations from cosmological simulations. While this work only gives a glimpse of the properties of typical galaxies that are thought to drive the reionization of the universe, it clearly shows the potential of JWST to unveil unprecedented details of galaxy formation in the first billion years.

We present the first rest-frame optical size–luminosity relation of galaxies at z > 7, using the NIRCam imaging data obtained by the GLASS James Webb Space Telescope Early Release Science (GLASS-JWST-ERS) program, providing the deepest extragalactic data of the ERS campaign. Our sample consists of 19 photometrically selected bright galaxies with m F444W ≤ 27.8 at 7 < z < 9 and m F444W < 28.2 at z ∼ 9−15. We measure the size of the galaxies in five bands, from rest-frame optical (∼4800 Å) to the UV (∼1600 Å) based on the Sérsic model, and analyse the size–luminosity relation as a function of wavelength. Remarkably, the data quality of the NIRCam imaging is sufficient to probe the half-light radius r e down to ∼100 pc at z > 7. Given the limited sample size and magnitude range, we first fix the slope to that observed for larger samples in rest-frame UV using Hubble Space Telescope samples. The median size r 0 at the reference luminosity M = −21 decreases slightly from rest-frame optical (600 ± 80 pc) to UV (450 ± 130 pc). We then refit the size–luminosity relation allowing the slope to vary. The slope is consistent with β ∼ 0.2 for all bands except F150W, where we find a marginally steeper slope of β = 0.53 ± 0.15. The steep UV slope is mainly driven by the smallest and faintest galaxies. If confirmed by larger samples, it implies that the UV size–luminosity relation breaks toward the faint end, as suggested by lensing studies.

We present a first look at the reddest 2–5 μm sources found in deep images from the GLASS Early Release Science program. We undertake a general search, i.e., not looking for any particular spectral signatures, for sources detected only in bands redder than is reachable with the Hubble Space Telescope, and which would likely not have been identified in pre-JWST surveys. We search for sources down to AB ∼27 (corresponding to >10σ detection threshold) in any of the F200W to F444W filters, with a >1 magnitude excess relative to F090W to F150W bands. Fainter than F444W >25 we find 56 such sources of which 37 have reasonably constrained spectral energy distributions to which we can fit photometric redshifts. We find the majority of this population (∼65%) as 2 < z < 6 star-forming low-attenuation galaxies that are faint at rest-frame ultraviolet-optical wavelengths, have stellar masses 108.5–109.5 M ⊙, and have observed fluxes at >2 μm boosted by a combination of the Balmer break and emission lines. The typical implied rest equivalent widths are ∼200 Å with some extreme objects up to ∼1000 Å. This is in contrast with brighter magnitudes where the red sources tend to be z < 3 quiescent galaxies and dusty star-forming objects. Our general selection criteria for red sources allow us to independently identify other phenomena as diverse as extremely low-mass (∼108 M ⊙) quiescent galaxies at z < 1, recovering recently identified z > 11 galaxies and a very cool brown dwarf.

BackgroundAccording to the world health organization, sexual health (SH) is “a state of physical, emotional, mental and social well-being in relation to sexuality”. Studies on the impact of juvenile idiopathic arthritis (JIA) on SH are scarce especially during the critical phase of adolescence. We can ask ourselves: are health professionals (HP) “good” interlocutors for JIA patients?ObjectivesWe aimed to determine the expectations of JIA adolescents (10-19 years) and the perceptions of their parents regarding exchanges with HP in the field of SH.MethodsA multicenter survey was performed in nine French rheumatology centers and three patient associations from September 2021 to April 2022, among JIA patients, aged 18-45 years and their parents. On the advice of two child psychologists and a psychiatrist, we interviewed an adult population to obtain convincing data about their adolescence with the necessary hindsight on the subject. Self-administered questionnaires were designed (for JIA patients and parents) after an extensive literature review and experts’ consensus and distributed to participants.Results76 patients and 43 parents completed the anonymous questionnaires.Most patients were women (75%), with a mean age of 26 (7.2) years and an education level higher than high school (89%). Parents were mainly mothers (88%), with a mean age of 54 (5.6) years and an education level higher than high school (56%).Half the patients considered that JIA impacted their love life. The main causes were body complexes (46%) and low self-esteem (40%). The impact on their sex life was not clear-cut. Love life was discussed with parents for 52% and sexual life for 20% of patients. 59% of patients reported they were comfortable to discuss SH with an HP (yet, only 26% had done). Their main sources of information were referees (at school (46%), family (43%)) or social networks (34%). If patients reported that SH has been discussed, it was mainly when the HP was proactive (56%), with the hospital rheumatologist (50%), from a biomedical perspective.Focusing the needs for optimal care, patients and parents agreed to address SH during an individual patient education session in hospital (51% vs 35%), a regular consultation (47% vs 53%) or a dedicated consultation by request of the adolescent without parents being informed (38% vs 21%). Most patients and parents agreed that the HP should be proactive (78% vs 70%).At hospital, for patients, the most competent or the most affordable HP were the gynecologist (68%; 47%, respectively), the rheumatologist (55%; 41%), and the psychologist (53%; 39%). Patients and parents both considered that a peer expert would make patients feel more comfortable (38% vs 37%); however, contrary to patients, fewer parents point out their skills (46% vs 25%, p>0.0276).The opportunity of a suitable moment (64% of patients vs 53% of parents), an HP comfortable with the subject (59% vs 53%), and availability of brochures (45% vs 49%) seemed to be helpful for both. The only statistically significant difference concerned HP gender, less cited by parents (7% vs 43%, p <0.0001).The use of digital resources was significantly more cited by patients than parents (video information (29% vs 9%, p=0.0127); smartphone application (25% vs 9%, p=0.0372)).79% of patients were looking for general information (impact of JIA and treatments on sexuality), discussion (68%), reassurance (65%), and listening (51%). General information (58%, p=0.0158) and discussion (39%, p=0.0022) were significantly less cited by parents.ConclusionTo our knowledge, this is the first study to address the SH needs of adolescents with JIA. HPs should take up this real need about SH, especially in hospital for adolescents and their parents. Indeed, there are expectations directly linked to the specifics of the disease. The main difference between patients and parents would be the use of digital tools. There could be an interesting vector of communication with adolescents if the sources are reliable and parents reassured about their content.AcknowledgementsThis work has obtained the financial support of the French Society of Rheumatology.Disclosure of InterestsNone Declared.

Background Systemic juvenile idiopathic arthritis (systemic JIA) is a severe disease with both systemic and joint inflammation. This study aims to identify predictors of disease evolution within the systemic JIA population enrolled in the Juvenile Inflammatory Rheumatism cohort (JIRcohort). Methods Observational patient cohort study with 201 recruited children from 4 countries (3 European, 1 North Africa) from 2005 until 2019, using retrospectively (2005–2015) and prospectively (2015–2019) routine care collected data. Results Sixty-five patients with complete follow-up data for 24 months after first diagnosis were classified as monophasic ( n  = 23), polyphasic ( n  = 6) or persistent group ( n  = 36) corresponding to their evolution (unique flare, recurrent flares, or persistent disease activity respectively). The patients of the persistent group were more likely to have an earlier disease onset, before the age of 6 (OR 2.57, 95%-CI 0.70–9.46), persistence of arthritis at 12-months post-diagnosis (OR 4.45, 95%-CI 0.58–34.20) and higher use of synthetic DMARD (sDMARD, OR 5.28, 95%-CI 1.39–20.01). Other variables like global assessment by physician and by patient and C Reactive Protein levels at 12-months post-diagnosis were assessed but without any predictive value after adjusting for confounding factors. Conclusions Our results suggest that the earlier disease onset, the persistence of arthritis throughout the first year of disease evolution and the need of sDMARD might predict a persistent disease course.

We spectroscopically confirm the M UV = −20.5 mag galaxy GHZ2/GLASS-z12 to be at redshift z = 12.34. The source was selected via NIRCam photometry in GLASS-JWST Early Release Science data, providing the first evidence of a surprising abundance of bright galaxies at z ≳ 10. The NIRSpec PRISM spectrum shows detections of N iv, C iv, He ii, O iii, C iii, O ii, and Ne iii lines and the first detection at high redshift of the O iii Bowen fluorescence line at 3133 Å rest frame. The prominent C iv line with rest-frame equivalent width (EW) ≈ 46 Å puts GHZ2 in the category of extreme C iv emitters. GHZ2 displays UV lines with EWs that are only found in active galactic nuclei (AGNs) or composite objects at low/intermediate redshifts. The UV line-intensity ratios are compatible with both AGNs and star formation in a low-metallicity environment, with the low limit on the [Ne iv]/[N iv] ratio favoring a stellar origin of the ionizing photons. We discuss a possible scenario in which the high ionizing output is due to low-metallicity stars forming in a dense environment. We estimate a metallicity ≲0.1 Z/Z ⊙, a high ionization parameter log U > −2, a N/O abundance 4–5 times the solar value, and a subsolar C/O ratio similar to the recently discovered class of nitrogen-enhanced objects. Considering its abundance patterns and the high stellar mass density (104 M ⊙ pc−2), GHZ2 is an ideal formation site for the progenitors of today's globular clusters. The remarkable brightness of GHZ2 makes it a “Rosetta stone” for understanding the physics of galaxy formation within just 360 Myr after the Big Bang.