A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51

Heteroatom-facilitated blue to near-infrared emission of nonconjugated polyesters

Making nonconjugated polymers to emit visible light remains a formidable challenge, let alone near-infrared (NIR) light, although NIR luminophores have many advanced applications. Herein, we propose an electron-bridging strategy of using heteroatoms (O, N, and S) to achieve tunable emission from blue to NIR regions (440-800 nm) in nonconjugated polyesters. Especially, sulfur-containing polyester P4 exhibits NIR clusteroluminescence (CL) on changing either the concentration or excitation wavelength. Experimental characterization and theoretical calculation demonstrate that the introduction of heteroatoms significantly enhances the through-space interactions (TSIs) via the electron-bridging effect between heteroatoms and carbonyls. The strength of the electron-bridging effect follows the order of S > N > O, based on two synergistic effects: electronic structure and van der Waals radius of heteroatoms. This work provides a low-cost, scalable platform to produce new-generation nonconjugated luminophores with deeper insight into the photophysical mechanism.

The nature of an ultra-faint galaxy in the cosmic dark ages seen with JWST

In the first billion years after the Big Bang, sources of ultraviolet (UV) photons are believed to have ionized intergalactic hydrogen, rendering the Universe transparent to UV radiation. Galaxies brighter than the characteristic luminosity L* (refs. ^1,2) do not provide enough ionizing photons to drive this cosmic reionization. Fainter galaxies are thought to dominate the photon budget; however, they are surrounded by neutral gas that prevents the escape of the Lyman-α photons, which has been the dominant way to identify them so far. JD1 was previously identified as a triply-imaged galaxy with a magnification factor of 13 provided by the foreground cluster Abell 2744 (ref. ³), and a photometric redshift of z ≈ 10. Here we report the spectroscopic confirmation of this very low luminosity (≈0.05 L*) galaxy at z = 9.79, observed 480 Myr after the Big Bang, by means of the identification of the Lyman break and redward continuum, as well as multiple ≳4σ emission lines, with the Near-InfraRed Spectrograph (NIRSpec) and Near-InfraRed Camera (NIRCam) instruments. The combination of the James Webb Space Telescope (JWST) and gravitational lensing shows that this ultra-faint galaxy (M_UV = -17.35)-with a luminosity typical of the sources responsible for cosmic reionization-has a compact (≈150 pc) and complex morphology, low stellar mass (10^7.19 M_⊙) and subsolar (≈0.6 Z_⊙) gas-phase metallicity.

Massive Galaxy Clusters Like El Gordo Hint at Primordial Quantum Diffusion

It is generally assumed within the standard cosmological model that initial density perturbations are Gaussian at all scales. However, primordial quantum diffusion unavoidably generates non-Gaussian, exponential tails in the distribution of inflationary perturbations. These exponential tails have direct consequences for the formation of collapsed structures in the Universe, as has been studied in the context of primordial black holes. We show that these tails also affect the very-large-scale structures, making heavy clusters like "El Gordo," or large voids like the one associated with the cosmic microwave background cold spot, more probable. We compute the halo mass function and cluster abundance as a function of redshift in the presence of exponential tails. We find that quantum diffusion generically enlarges the number of heavy clusters and depletes subhalos, an effect that cannot be captured by the famed f_{NL} corrections. These late-Universe signatures could, thus, be fingerprints of quantum dynamics during inflation that should be incorporated in N-body simulations and checked against astrophysical data.

Sixty Challenges – A 2030 Perspective on Natural Products and Medicines Security

Natural products matter, for they are essential contributors to societal well-being and global health. Flavors, fragrances, essential oils, traditional medicines and phytopharmaceuticals, and prescription and over-the-counter products all utilize constituent materials from natural sources. However, these vast natural resources of Earth are disappearing, and climate change and market expansion by a dramatically increasing and ageing population will continue to strain plant sourcing in the decades ahead. It was with these and other considerations that the term “ecopharmacognosy” was developed as both a philosophy and a practice, and from which the necessity for a “medicines security” strategy evolved.

Extending previous presentations, a series of sixty challenges for 2030 to the status quo promotes the discussion of a different vision for the natural product sciences as applied to traditional medicines. Among the topics presented are areas for global collaborative initiatives in science and in data management, the impact of climate change on medicinal plant accessibility, the sustainability and quality of the natural products that patients receive, and the integration of new technologies, particularly the genomics of secondary metabolite biosynthesis, hand-held detection systems and artificial intelligence, and the implications of increased life expectancy on future health care needs. The presentation closes with two examples of newer approaches in drug discovery.

The formation of submillimetre-bright galaxies from gas infall over a billion years

Submillimetre-bright galaxies at high redshift are the most luminous, heavily star-forming galaxies in the Universe and are characterized by prodigious emission in the far-infrared, with a flux of at least five millijanskys at a wavelength of 850 micrometres. They reside in haloes with masses about 10(13) times that of the Sun, have low gas fractions compared to main-sequence disks at a comparable redshift, trace complex environments and are not easily observable at optical wavelengths. Their physical origin remains unclear. Simulations have been able to form galaxies with the requisite luminosities, but have otherwise been unable to simultaneously match the stellar masses, star formation rates, gas fractions and environments. Here we report a cosmological hydrodynamic galaxy formation simulation that is able to form a submillimetre galaxy that simultaneously satisfies the broad range of observed physical constraints. We find that groups of galaxies residing in massive dark matter haloes have increasing rates of star formation that peak at collective rates of about 500-1,000 solar masses per year at redshifts of two to three, by which time the interstellar medium is sufficiently enriched with metals that the region may be observed as a submillimetre-selected system. The intense star formation rates are fuelled in part by the infall of a reservoir gas supply enabled by stellar feedback at earlier times, not through major mergers. With a lifetime of nearly a billion years, our simulations show that the submillimetre-bright phase of high-redshift galaxies is prolonged and associated with significant mass buildup in early-Universe proto-clusters, and that many submillimetre-bright galaxies are composed of numerous unresolved components (for which there is some observational evidence).

A dusty, normal galaxy in the epoch of reionization

Candidates for the modest galaxies that formed most of the stars in the early Universe, at redshifts z > 7, have been found in large numbers with extremely deep restframe-ultraviolet imaging. But it has proved difficult for existing spectrographs to characterize them using their ultraviolet light. The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant galaxy discovered via its ultraviolet emission and subsequently detected in dust emission is only at z = 3.2 (ref. 5), and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at z ≥ 7. Here we report thermal dust emission from an archetypal early Universe star-forming galaxy, A1689-zD1. We detect its stellar continuum in spectroscopy and determine its redshift to be z = 7.5 ± 0.2 from a spectroscopic detection of the Lyman-α break. A1689-zD1 is representative of the star-forming population during the epoch of reionization, with a total star-formation rate of about 12 solar masses per year. The galaxy is highly evolved: it has a large stellar mass and is heavily enriched in dust, with a dust-to-gas ratio close to that of the Milky Way. Dusty, evolved galaxies are thus present among the fainter star-forming population at z > 7.