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Abstract The metallicity of galaxies, and its variation with galactocentric radius, provides key insights into the formation histories of galaxies and the physical processes driving their evolution. In this work, we analyze the radial metallicity gradients of star-forming galaxies in the EAGLE, Illustris, IllustrisTNG, and SIMBA cosmological simulations across broad mass (10^8.0M_⊙≤M_⋆ ≲ 10^12.0M_⊙) and redshift (0 ≤z≤ 8) ranges. We find that all simulations predict strong negative (i.e., radially decreasing) metallicity gradients at early cosmic times, likely due to their similar treatments of relatively smooth stellar feedback not providing sufficient mixing to quickly flatten gradients. The strongest redshift evolution occurs in galaxies with stellar masses of 10^10.0–10^11.0M_⊙, while galaxies with stellar mass < 10¹⁰M_⊙and >10¹¹M_⊙exhibit weaker redshift evolution. Our result of negative gradients at high redshift contrast with the many positive and flat gradients in the 1 < z < 4 observational literature. Atz > 6, the negative gradients observed with JWST and the Atacama Large Millimeter/submillimeter Array are flatter than those in simulations, albeit with closer agreement than at lower redshift. Overall, we suggest that these smooth stellar feedback galaxy simulations may not sufficiently mix their metal content radially, and that either stronger stellar feedback or additional subgrid turbulent metal diffusion models may be required to better reproduce observed metallicity gradients. 

Abstract We present in this paper (Paper II of the series) a 35 arcmin²JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar atz= 6.61. The F356W grism data reveal 124 [Oiii]+Hβemitters at 5.3 < z < 7, 53 of which constitute a protocluster spanning (10 cMpc)²across 6.5 < z < 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median HβFWHM of 585 ± 152 km s⁻¹; however, the mass–excitation diagram and “little red dot” color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [Oiii] emitters withProspectorandBagpipesand find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3σlevel, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure. 

Abstract A SPectroscopic survey of bIased halos in the Reionization Era is a quasar legacy survey primarily using JWST to target a sample of 25z > 6 quasars with NIRCam slitless spectroscopy and imaging. The first study in this series found evidence of a strong overdensity of galaxies around J0305−3150, a luminous quasar atz= 6.61, within a single NIRCam pointing obtained in JWST Cycle 1. Here we present the first results of a JWST Cycle 2 mosaic that covers 35 arcmin²with NIRCam imaging/wide-field slitless spectroscopy of the same field to investigate the spatial extent of the putative protocluster. The F356W grism data target [Oiii]+Hβat 5.3 < z < 7 and reveal a population of 124 line emitters down to a flux limit of 1.2 × 10⁻¹⁸erg s⁻¹cm⁻². Fifty-three of these galaxies lie at 6.5 < z < 6.8 spanning 10 cMpc on the sky, corresponding to an overdensity within a 2500 cMpc³volume of 12.5 ± 2.6, anchored by the quasar. Comparing to the [Oiii] luminosity function from the Emission line galaxies and Intergalactic Gas in the Epoch of Reionization project, we find a dearth of faint [Oiii] emitters at log(L/erg s⁻¹) < 42.3, which we suggest is consistent with either bursty star formation causing galaxies to scatter around the grism detection limit or modest suppression from quasar feedback. While we find a strong filamentary overdensity of [Oiii] emitters consistent with a protocluster, we suggest that we could be insensitive to a population of older, more massive Lyman break galaxies with weak nebular emission on scales >​​​​​​10 cMpc. 

Abstract Conjugation is used by bacteria to propagate antimicrobial resistance (AMR) in the environment. Central to this process are widespread conjugative F-pili that establish the connection between donor and recipient cells, thereby facilitating the spread of IncF plasmids among enteropathogenic bacteria. Here, we show that the F-pilus is highly flexible but robust at the same time, properties that increase its resistance to thermochemical and mechanical stresses. By a combination of biophysical and molecular dynamics methods, we establish that the presence of phosphatidylglycerol molecules in the F-pilus contributes to the structural stability of the polymer. Moreover, this structural stability is important for successful delivery of DNA during conjugation and facilitates rapid formation of biofilms in harsh environmental conditions. Thus, our work highlights the importance of F-pilus structural adaptations for the efficient spread of AMR genes in a bacterial population and for the formation of biofilms that protect against the action of antibiotics. 

We present JWST/NIRSpec integral field data of the quasar PJ308-21 atz = 6.2342. As shown by previous ALMA and HST imaging, the quasar has two companion sources, interacting with the quasar host galaxy. The high-resolution G395H/290LP NIRSpec spectrum covers the 2.87 − 5.27 μm wavelength range and shows the rest-frame optical emission of the quasar with exquisite quality (signal-to-noise ratio ∼100 − 400 per spectral element). Based on the Hβline from the broad line region, we obtain an estimate of the black hole massM_BH, Hβ ∼ 2.7 × 10⁹ M_⊙. This value is within a factor ≲1.5 of the Hα-based black hole mass from the same spectrum (M_BH, Hα ∼ 1.93 × 10⁹ M_⊙) and is consistent with a previous estimate relying on the Mg IIλ2799 line (M_BH, MgII ∼ 2.65 × 10⁹ M_⊙). All theseM_BHestimates are within the ∼0.5 dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21λ_Edd, Hβ ∼ 0.67 (λ_Edd, Hα ∼ 0.96) is in line with the overall quasar population atz ≳ 6. The relative strengths of the [O III], Fe II, and Hβlines are consistent with the empirical “Eigenvector 1” correlations as observed for low redshift quasars. We find evidence for blueshifted [O III]λ5007 emission with a velocity offset Δv_{[O III]} = −1922 ± 39 km s⁻¹from the systemic velocity and a full width at half maximum (FWHM)FWHM([O III]) = 2776₋₇₄⁺⁷⁵km s⁻¹. This may be the signature of outflowing gas from the nuclear region, despite the true values of Δv_{[O III]}andFWHM([O III]) likely being more uncertain due to the blending with Hβand Fe IIlines. Our study demonstrates the unique capabilities of NIRSpec in capturing quasar spectra at cosmic dawn and studying their properties in unprecedented detail. 

Abstract Luminous quasars are powerful targets to investigate the role of feedback from supermassive black holes (BHs) in regulating the growth phases of BHs themselves and of their host galaxies, up to the highest redshifts. Here we investigate the cosmic evolution of the occurrence and kinematics of BH-driven outflows, as traced by broad absorption line (BAL) features, due to the C iv ionic transition. We exploit a sample of 1935 quasars at z = 2.1–6.6 with bolometric luminosity log( L bol /erg s −1 ) ≳ 46.5, drawn from the Sloan Digital Sky Survey and from the X-Shooter legacy survey of Quasars at the Reionization Epoch (XQR-30). We consider rest-frame optical bright quasars to minimize observational biases due to quasar selection criteria. We apply a homogeneous BAL-identification analysis, based on employing composite template spectra to estimate the quasar intrinsic emission. We find a BAL quasar fraction close to 20% at z ∼ 2–4, while it increases to almost 50% at z ∼ 6. The velocity and width of the BAL features also increase at z ≳ 4.5. We exclude the possibility that the redshift evolution of the BAL properties is due to differences in terms of quasar luminosity and accretion rate. These results suggest significant BH feedback occurring in the 1 Gyr old universe, likely affecting the growth of BHs and, possibly, of their host galaxies, as supported by models of early BH and galaxy evolution. 

Abstract Flagellar filaments function as the propellers of the bacterial flagellum and their supercoiling is key to motility. The outer domains on the surface of the filament are non-critical for motility in many bacteria and their structures and functions are not conserved. Here, we show the atomic cryo-electron microscopy structures for flagellar filaments from enterohemorrhagic Escherichia coli O157:H7, enteropathogenic E. coli O127:H6, Achromobacter , and Sinorhizobium meliloti , where the outer domains dimerize or tetramerize to form either a sheath or a screw-like surface. These dimers are formed by 180° rotations of half of the outer domains. The outer domain sheath (ODS) plays a role in bacterial motility by stabilizing an intermediate waveform and prolonging the tumbling of E. coli cells. Bacteria with these ODS and screw-like flagellar filaments are commonly found in soil and human intestinal environments of relatively high viscosity suggesting a role for the dimerization in these environments. 

Abstract We present measurements of black hole masses and Eddington ratios (λ_Edd) for a sample of 38 bright (M₁₄₅₀< −24.4 mag) quasars at 5.8 ≲z≲ 7.5, derived from Very Large Telescope/X–shooter near–IR spectroscopy of their broad Civand Mgiiemission lines. The black hole masses (on average,M_BH∼ 4.6 × 10⁹M_⊙) and accretion rates (0.1 ≲λ_Edd≲ 1.0) are broadly consistent with that of similarly luminous 0.3 ≲z≲ 2.3 quasars, but there is evidence for a mild increase in the Eddington ratio abovez≳ 6. Combined with deep Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 158μm line from the host galaxies and VLT/MUSE investigations of the extended Lyαhalos, this study provides fundamental clues to models of the formation and growth of the first massive galaxies and black holes. Compared to local scaling relations,z≳ 5.7 black holes appear to be over-massive relative to their hosts, with accretion properties that do not change with host galaxy morphologies. Assuming that the kinematics of theT∼ 10⁴K gas, traced by the extended Lyαhalos, are dominated by the gravitational potential of the dark matter halo, we observe a similar relation between black hole mass and circular velocity as reported forz∼ 0 galaxies. These results paint a picture where the first supermassive black holes reside in massive halos atz≳ 6 and lead the first stages of galaxy formation by rapidly growing in mass with a duty cycle of order unity. The duty cycle needs to drastically drop toward lower redshifts, while the host galaxies continue forming stars at a rate of hundreds of solar masses per year, sustained by the large reservoirs of cool gas surrounding them. 

Abstract Studies of rest-frame optical emission in quasars at z > 6 have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at z > 6.5 using the JWST/NIRCam Wide Field Slitless Spectroscopy as a part of the “A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)” program. Our JWST spectra cover the quasars’ emission between rest frame ∼4100 and 5100 Å. The profiles of these quasars’ broad H β emission lines span a full width at half maximum from 3000 to 6000 km s −1 . The H β -based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their Mg ii -based BH masses. The new measurements based on the more reliable H β tracer thus confirm the existence of a billion solar-mass BHs in the reionization epoch. In the observed [O iii ] λ λ 4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components (≤ 1200 km s −1 ), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [O iii ] emission, thought to trace galactic-scale outflows, with median velocities of −610 and −1430 km s −1 relative to the [C ii ] 158 μ m line. All eight quasars show strong optical Fe ii emission and follow the eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.