We present the Parallel Application of Slitless Spectroscopy to Analyze Galaxy Evolution (PASSAGE) spectroscopic redshift catalog in the COSMOS field. PASSAGE is a JWST Cycle 1 Near Infrared Imager and Slitless Spectrograph (or NIRISS) wide-field slitless spectroscopy pure-parallel survey, obtaining near-infrared spectra of thousands of extragalactic sources. Fifteen out of 63 PASSAGE fields fall within the Hubble Space Telescope COSMOS footprint, of which 11 overlap with COSMOS-Web, a JWST treasury survey providing additional space-based photometry. We present our custom line-finding algorithm and visual inspection effort used to identify emission lines and derive the spectroscopic redshifts for line-emitting sources in PASSAGE. The line-finding algorithm identifies between similar to 200 and 950 line-emitting candidates per field, of which typically 47% were identified as true emission lines post visual inspection. We identify 2183 emission-line sources at 0.08 less than or similar to z less than or similar to 4.7, 1896 of which have available COSMOS photometric redshifts. We find excellent redshift agreement between the COSMOS photometric redshifts and the PASSAGE spectroscopic redshifts for strong (signal-to-noise ratio > 5), multi-line-emitting sources. This agreement weakens for PASSAGE single-line emitters with ambiguous identities. These single-line emitters are likely misidentified around 18% of the time based on comparisons to photometric redshifts. We derive stellar masses using PASSAGE photometry and spectroscopic redshifts, in broad agreement with existing COSMOS-Web stellar masses, but with some discrepancy driven by redshift disagreements. We publicly release this spectroscopic redshift catalog, which will enable community-led science in prime extragalactic fields and serve as a crucial dataset for validating Euclid and Roman spectroscopy.

This manuscript presents JWST MIRI/MRS observations of the central r ≈ 40-240 pc regions of five active galactic nuclei (AGN) spanning a wide range of luminosities (log L_ bol/ erg s^-1≈ 39.8-43.8). Combining multiphase diagnostics from polycyclic aromatic hydrocarbons (PAHs), molecular hydrogen (H_2), and ionized gas at spatial scales of ∼ 4-24 pc, this study presents a spatially resolved investigation into the effects of the two distinct AGN feedback modes–radiative and kinetic–on the surrounding medium. The results indicate that these two feedback modes, associated with AGN irradiation and shock processing, respectively, collectively drive the relative suppression of PAH emission in the nuclear regions of the targets studied here. Moreover, the coexistence of these two AGN feedback modes, especially the shock processing associated with either jets or outflows, in the central regions of AGN naturally explains both the bimodal distribution of PAH band ratios observed in the targets studied here and the seemingly disparate results reported in the literature. Although based on a limited sample, these findings provide new insights into calibrating star-formation rates (SFRs) from PAH emission in AGN, and more importantly, lay the groundwork for a practical framework to diagnose and quantify AGN feedback in the JWST era.

We compile JWST/NIRSpec prism and MIRI data for 249 Little Red Dots (LRDs) at 2.3<z<9.3, forming a representative spectroscopic subset of NIRCam-selected LRDs. We derive a median stacked spectrum covering rest-frame 0.09-1.2 μm, with MIRI photometry extending the spectral energy distribution to 4 μm. Four additional stacks for subsamples defined by optical-to-UV luminosity ratios show that LRDs form a heterogeneous population spanning diverse continuum slopes and line properties. Assuming LRDs host super-massive black holes (BHs) surrounded by dense gas clouds, and stars accompany this core, we infer masses of M_BH∼10^6.0-6.5 M_⊙ and M_∼10^8.3 M_⊙, corresponding to BH-to-stellar mass ratios of 1-2

Our understanding of the physical properties of star-forming galaxies during the Epoch of Reionization (EoR; at z > 6) suffers from degeneracies among the apparent properties of the stars, nebular gas, and dust. These degeneracies are most prominent with photometry, which has insufficient (1) spectral resolution and (2) rest-frame spectral coverage. We explore ways to break these degeneracies with a sample of N = 22 high-redshift star-forming galaxies at 7 < z(phot) <= 9, using some of the deepest existing imaging from JWST/NIRCam and JWST/MIRI with JADES. Key to this study is the imaging from JWST/MIRI at 7.7 mu m, which provides coverage of the rest-frame I band at the observed redshifts. We infer stellar population properties and rest-frame colors using a variety of filter sets and star formation history (SFH) assumptions to explore the impact of these choices. Evaluating these quantities both with and without the 7.7 mu m data point shows that dense spectral coverage with JWST/NIRCam (eight or more filters, including at least one medium-band at lambda(obs) approximate to 4-5 mu m) can compensate for lacking the rest-frame I-band coverage for the vast majority (approximate to 80%) of our sample. Furthermore, these galaxy properties are most consistently determined by assuming the delayed-tau SFH, which provides the smallest offsets and scatters around these offsets when including JWST/MIRI. Within extragalactic surveys like JADES and CEERS, our findings suggest that robust characterization of the stellar population properties and rest-frame colors for typical high-redshift star-forming galaxies (i.e., galaxies with M-UV approximate to -20 and beta(UV) approximate to -2) is possible with JWST/NIRCam alone at z approximate to 8.

We systematically search for galaxy overdensities using 20 independent fields with a minimum of six filters (F090W, F115W, F150W, F277W, F356W, and F444W) from BEACON, the JWST Cycle 2 NIRCam pure-parallel imaging survey. We apply an adaptive kernel-density estimation method that incorporates the full photometric redshift probability distribution function of each galaxy to map galaxy overdensities, and identify 207 significant (>4 σ) overdensities at 1.53, potentially due to a larger cold gas supply in earlier times. Our study reveals a complex interplay between individual galaxies and large-scale environmental properties, marking the onset of environmental effects on galaxy quenching in massive halos at cosmic noon.

We present James Webb Space Telescope /Mid-Infrared Instrument imaging of eight nearby active galactic nuclei (AGN) from the GATOS (Galactic Activity, Torus, and Outflow Survey) survey to investigate the physical conditions of extended dust in their narrow-line regions (NLRs). In four galaxies (ESO 428-G14, NGC 4388, NGC 3081, and NGC 5728), we detect spatially resolved dust structures extending '100-200 pc along the NLR. In these systems, we find a strong link between the morphology of the dust, the radio ejecta, and the coronal [Si vi ] emission, implying that dust carries imprints of the processes shaping the NLR. Using spatially resolved spectral energy distributions, we show that dust in the NLR has systematically steeper slopes than star-forming clumps. This dust emits at temperatures in the range 150-220 K , at a distance of similar to 150 pc from the nucleus. Using simple models, we show that, even under optimistic assumptions of grain size and AGN luminosity, the excess mid-infrared emission cannot be explained by AGN illumination alone. We interpret this excess heating as in situ . We show that shocks with velocities v(shock) similar to 200-400 km s(-1) in dense gas can close this gap, and in some cases even account for the total observed emission. This, combined with multiple lines of evidence for shocks in these regions, supports a scenario in which shocks not only coexist with dust but may be playing a key role in heating it. Our findings reveal shocks may be an important and previously overlooked driver of extended dust emission in the central hundreds of parsecs in AGN.

ABSTRACT The discovery of high-redshift galaxies exhibiting a steep spectral ultraviolet (UV) downturn potentially indicative of two-photon continuum emission marks a turning point in our search for signatures of star formation following a top-heavy initial mass function in the early Universe. We develop a photometric search method for identifying further nebular-dominated galaxy candidates, whose nebular continuum dominates over the starlight, due to the high ionizing photon production efficiencies $\xi _\mathrm{ion}$ associated with massive star formation. We utilize the extensive medium-band imaging from the JWST Advanced Deep Extragalactic Survey (JADES), which enables the identification of Balmer jumps across a wide range of redshifts ($1.5 \lt z \lt 8.5$), through the deficit in rest-frame optical continuum level. As Balmer jumps are a general recombination feature of young starbursts ($\lesssim 3$ Myr), we further demand a high observed $\log \, (\xi _\mathrm{ion, obs}/\mathrm{(Hz\ erg^{-1})}) \gt 25.60$ to power the strong nebular continuum, together with a relatively non-blue UV slope ($m_\mathrm{F115W}-m_\mathrm{F200W} \gt -0.4$ at $z=6$) indicating a lack of stellar continuum emission. Our nebular-dominated candidates, constituting ${\sim }11$ per cent of galaxies at $z \sim 6$ (decreasing to ${\sim }2$ per cent at $z \sim 2$, not completeness-corrected) are faint in the rest-frame optical (median $M_\mathrm{opt} = -17.95$) with extreme line emission (median $\mathrm{EW}_\mathrm{H\alpha , rest} = 1567$ Å, $\mathrm{EW}_\mathrm{[O\ III] + H\beta ,rest} = 2292$ Å). However, hot H ii region temperatures, collisionally enhanced two-photon continuum emission, and strong UV lines are expected to accompany top-heavy star formation. Thus nebular-dominated galaxies do not necessarily exhibit the biggest Balmer jumps, nor the largest $\xi _\mathrm{ion, obs}$ or reddest UV slopes. Hence continuum spectroscopy is ultimately required to establish the presence of a two-photon downturn in our candidates, thus advancing our understanding of primordial star formation and active galactic nucleus.

James Webb Space Telescope JWST uncovered a large number of massive quiescent galaxies (MQGs) at z > 3, which theoretical models struggle to reproduce. Explaining the number density of such objects requires extremely high conversion efficiency of baryons into stars in early dark matter halos. Using stellar kinematics, we can investigate the processes shaping the mass assembly histories of MQGs. We present high-resolution JWST/NIRSpec integral field spectroscopy of GS-9209, a massive, compact quiescent galaxy at z = 4.66 (log (M-*/M-circle dot) = 10.52 +/- 0.06, R-eff = 220 +/- 20 pc). Full spectral fitting of the spatially resolved stellar continuum reveals a clear rotational pattern, yielding a spin parameter of lambda(2Reff )= 0.85 +/- 0.10. This study suggests that at least a fraction of the earliest quiescent galaxies were fast rotators and that quenching was a dynamically gentle process, preserving the stellar disc even in highly compact objects. Using Jeans anisotropic modelling and assuming a NFW profile, we measure a dark matter fraction of f(DM )( < 2R(eff)) = 14.5(-4.2)(+6.0) per cent. Our findings use stellar kinematics to confirm the massive nature of early quiescent galaxies, previously inferred from stellar population modelling. We suggest that GS-9209 has a similar structure to low-redshift 'relic' galaxies. However, unlike relic galaxies which have bottom-heavy initial mass functions (IMF), the dynamically inferred stellar mass-to-light ratio of GS-9209 is consistent with a Milky-Way like IMF. The kinematical properties of GS-9209 are different from those of z < 1 early-type galaxies and more similar to those of recently quenched post-starburst galaxies at z > 2.

Spatially resolved gas-phase metallicity maps are a crucial element in building our understanding of the chemical evolution of galaxies. We present spatially resolved metallicity maps obtained from NIRISS/WFSS observations in the first work delivering such an analysis of the slitless spectroscopy of multiple galaxies. We investigated the sources of ionization, metallicity, and their relation to star formation in a spatially resolved sense for a sample of eight galaxies: four from JWST-PASSAGE and four from GLASS-JWST ERS. All but one of these galaxies reside in the redshift range 1.9 ≤ z ≤ 2, the outlier being at z = 3.1. Our sample covers a range of 8.0 < log (M ⋆ / M ⊙ ) < 9.5 in terms of stellar mass, 0.2 < log (SFR M ⊙ yr −1 ) < 1.1 in the star formation rate (SFR), and 7.8 < 12 + log(O / H) < 9.0 in the global gas metallicity. To resolve the question of the star formation-AGN separation in the absence of resolved H α +[NII] lines, we present a new SF-demarcation line in the OHNO parameter space, based on MAPPINGS v5.1 publicly available H II region and AGN model grids, with the caveat that these grids partially overlap the OHNO parameter space. We present the mass-metallicity gradient relation for our sample, which show no clear trend with stellar mass. This might be because the high- z galaxies have not yet started their accretion-dominated evolutionary phase. By interpreting the correlation between spatially resolved metallicity and SFR maps as a proxy for effective timescales of metal-transport in galaxies, we find a possible trend that sees this timescale increasing with stellar mass. This is consistent with the picture of more effective feedback in lower mass galaxies and where massive galaxies generally tend to have longer characteristic timescales.

In Paper I, we exploited the unsurpassed resolution and depth of JWST/NIRCam imagery to investigate the relationship between active galactic nuclei (AGN) and host-galaxy properties in the JWST era, finding a correlation between the level of spatial disturbance (as measured by shape asymmetry, A _S ) and obscuration ( N _H ). Here in Paper II, we report an expansion of our X-ray and infrared analysis of Seyfert-luminosity host galaxies with four additional metrics to the single-metric morphology analysis of Paper I, as well as new samples of inactive control galaxies. This expanded study of one of the largest and most complete, multiwavelength samples of AGN detected at 0.6 < z < 3.8 in the GOODS-South and -North fields, confirms that mergers surprisingly play a significant role in obscured, subquasar AGN host galaxies. Additionally, the pattern of morphological disturbances observed amongst the X-ray- and mid-IR-selected AGN suggests that these represent different phases of AGN evolution tied to a major-merger timeline, as opposed to distinct populations of AGN. These results indicate that mergers are important in triggering subquasar AGN at these redshifts.

The unexpectedly high abundance of galaxies at z > 11 revealed by JWST has sparked a debate on the nature of early galaxies and the physical mechanisms regulating their formation. The Atacama Large Millimeter/submillimeter Array (ALMA) has begun to provide vital insights on their gas and dust content, but so far only for extreme 'blue monsters'. Here we present new, deep ALMA observations of JADES-GS-z11-0, a more typical (sub-L^*) z > 11 galaxy that bridges the discovery space of JWST and the Hubble Space Telescope. These data confirm the presence of the [O III] 88 μm line at 4.5σ significance, precisely at the redshift of several faint emission lines previously seen with JWST/NIRSpec, while the underlying dust continuum remains undetected (F_ν< 9.0 μJy), implying an obscured star formation rate (SFR) of SFR_IR≲ 6 M_⊙ yr^-1 and dust mass of M_dust≲ 1.0 × 10^6 M_⊙ (all 3σ). The accurate ALMA redshift of z_[O III] = 11.1221 ± 0.0006 (≳ 5× refined over NIRSpec) helps confirm that redshifts measured purely from the Lyman-α break, even spectroscopically, should properly take into account the effects of potential damped Lyman-α absorption (DLA) systems to avoid systematic overestimates of up to Δz ≈ 0.5. The [O III] 88 μm luminosity of L_[O III] = (1.0 ± 0.3) × 10^8 L_⊙, meanwhile, agrees well with the scaling relation for local metal-poor dwarfs given the SFR measured by NIRCam, NIRSpec, and MIRI. The spatially resolved MIRI and ALMA emission also underscores that JADES-GS-z11-0 is likely to consist of two low-mass components that are undergoing strong bursts of star formation yet are already pre-enriched in oxygen ( 30

Despite the growing number of compact active galactic nuclei (AGN) at z>4 discovered by JWST, their formation and evolution remain poorly understood. This paper investigates the large-scale environment of GN-77652, a compact AGN at z=5.229 observed as part of the JWST NIRSpec IFU Large Program BlackTHUNDER and complemented by deep multi-band NIRCam imaging. GN-77652 lies in close proximity to a 12 kpc-long filament composed of multiple sources at z≃5.23, spanning a remarkable range in stellar masses (M_⋆=0.7-13 × 10^8 M_⊙), gas phase metallicities (12+log(O/H) = 7.6-8.5) and star formation rates (SFR =0.4-6 M_⊙ yr^-1). The [OIII]λ5007 kinematics reveals a smooth large-scale velocity gradient centred on the central, massive (M_⋆≃1.1×10^9 M_⊙) and metal rich (Z∼0.6 Z_⊙) system of the group. In this source, only 2.4 kpc (projected) from GN-77652, [OIII]λ4363 line diagnostics provide possible evidence for a second AGN. GN-77652 exhibits a shallow (-30 to +20 km s^-1) velocity gradient that is consistent with disk rotation according to dynamical modelling. The Lyman-Werner radiation field produced by the filament is too weak for the black hole (BH) in GN-77652 to have formed recently via direct collapse. However, the required conditions may have existed at earlier epochs, or alternative scenarios (e.g. a recoiling BH ejected from the filament) could also be plausible. The whole system is expected to coalesce in 150-440 Myr, also motivating an exploration of its future evolution through toy-model extrapolations and numerical simulations. Our analysis suggests that the compact AGN appearance of GN-77652 represents a transient evolutionary phase, consistent with the apparent decline with redshift in number density of compact AGN identified with JWST.

The depth and coverage of the first years of James Webb Space Telescope observations have revealed low-luminosity active galactic nuclei (AGN) across a wide redshift range, shedding light on black hole (BH) assembly and feedback. We present our spectroscopic sample of 34 Type 1 AGN obtained from JADES survey data and spanning 1 . 5 < z < 9 . Our sample of AGN probes a BH mass range of 10(6-9) M(circle dot)at bolometric luminosities down to 10(43) erg s(-1). Most of these AGN are hosted in low-mass ( M-* similar to 10(8) M-circle dot) galaxies and are overmassive relative to the local M-BH-M-* relation, while remaining consistent with the local M-BH-sigma(*) relation. The wide redshift range provided by our sample allows us to trace the emergence of local M-BH-M-* scaling relation across cosmic time. Additionally, we explore the capability of narrow-line diagnostics in identifying Type 2 AGN and find that a significant fraction of our AGN would be missed by them due to low metallicity or lack of high-energy ionizing photons. We explore the UV luminosity function of AGN and their hosts and find that it is subject to significant cosmic variance and is also dependent on the AGN bolometric luminosity . Finally , we show that the electron scattering scenario recently proposed to explain broad Balmer lines is untenable on multiple grounds showing that there is no evidence of significant BH mass overestimation.

We present gas-phase abundances of carbon (C), alpha-elements (O, Ne, Si, and Ar), and iron (Fe) obtained from stacked spectra of high-z star-forming galaxies with the deep Near Infrared Spectrograph medium-resolution data from the James Webb Space Telescope Advanced Deep Extragalactic Survey. Our 564 sources at z=4-7 have a median stellar mass of log (M-*/ M-circle dot)=8.46 and a median star-formation rate of log (SFR}/M-circle dot, yr(-1))=0.30, placing them close to the star-formation main sequence. We find that the stacked spectrum of all our 564 sources has relatively low [C/O]=-0.70, moderate [Ne/O]=-0.09, and low [Ar/O]=-0.28 values at a low gas-phase metallicity of 12+log (O/H)=7.71 (Z similar to 0.1 Z(circle dot)), suggesting dominant yields of core-collapse supernovae evolved from massive stars. The detection of a weak [Si iii] emission line in our stacked spectrum provides a silicon-to-oxygen abundance ratio of [Si/O]=-0.63, which is lower than that of stars in the Milky Way disc and lower than expected by chemical evolution models, suggesting silicon depletion on to dust grains. Likewise, this Si/O value is lower than that we newly derive for two individual z>6 galaxies (GN-z11 and RXCJ2248) with negligible dust attenuation. By performing spectral stacking in bins of M-*, star-formation rate (SFR), specific SFR (sSFR), and ultraviolet continuum slope beta(UV), we identify [Fe iii] line detections in the high-sSFR bin and the blue- beta(UV) bin, both of which exhibit supersolar Fe/O ratios, while their C/O, Ar/O, and Si/O ratios are comparable to those of the all-sources stack. Our findings support a chemically young gas composition with rapid dust depletion in the general population of high-z star-forming galaxies, while raising the possibility of anomalous, selective Fe/O enhancement at the very early epoch of star formation.

JWST has revealed a large population of massive black holes (BHs) in the early Universe with unusual properties which mark them as distinct from low-redshift active galactic nuclei. Such findings have prompted the development of new models of BH formation and growth, and of their co-evolution with host galaxies. Linking the gas-phase metallicity of BH environments to seed masses is key to understanding which evolutionary pathways could explain the population of JWST-discovered BHs. We present new high-resolution JWST NIRSpec/IFU observations covering the rest-frame optical emission lines of a Little Red Dot (LRD) at z=3.55, known as The Cliff, from the `Red Unknowns: Bright Infrared Extragalactic Survey' (RUBIES). We find evidence for low metallicity (Z=0.017±0.004 Z_⊙) based on the low narrow-line [OIII]λ5007/Hβ ratio, supported by the non-detection of low-ionisation emission lines such as [OII]λλ3727,3729 and [NII]λλ6548,6583. We find that the observed properties of The Cliff, including its overmassive BH, can be reproduced by some simulations of black hole growth and evolution down to z∼3.5. However, these simulation runs require high seed masses (10^4 - 10^5 M_⊙) and appear as rarely in the simulation volume as in the RUBIES survey volume over redshifts 3<z<4, highlighting the unusual nature of The Cliff. Future simulations and numerical models will help to uncover how such a metal poor system managed to develop a massive black hole and persist to such low redshift.

JWST is beginning to uncover a population of extremely metal-poor galaxies (EMPGs, Z < 1% Z_⊙) at z > 3, mostly through serendipitous NIRSpec discoveries and blind slitless spectroscopy. To accelerate our understanding of pristine star formation, we further develop a methodology to identify EMPG candidates from photometry, using the extensive deep medium-band imaging from JADES. Our EMPG candidates at 2.5 < z < 6.5 exhibit strong photometric boosts by Hα, yet correspondingly weak boosts by [O III] + Hβ, likely indicating extremely low metallicity to explain their lack of [O III] emission. We further demand our EMPG candidates to have strong Balmer jumps, as revealed by medium-band imaging, to ensure that they are young starbursts, as opposed to broad-line AGN/LRDs, though contamination by dusty/dense-gas starbursts and highly-obscured AGN remains a concern. SED-fitting with near-pristine models (∼0.1-1% Z_⊙) indicates that our 22 EMPG candidates are low-mass (median M_* ≈ 10^6.7 M_⊙), faint dwarf galaxies (M_UV≈ -16.6), with high ionizing photon production efficiencies (log (ξ_ion, obs/(Hz erg^-1)) ≈ 26.0). Hence these are plausible sites of near-pristine star formation, comprising ∼0.04-0.6% of 2.5 < z < 6.5 galaxies at -19 < M_UV < -16. We discuss this extremely metal-poor extension to the mass-metallicity relation. We forecast that deep (∼28 h) NIRCam slitless spectroscopy can identify bright EMPGs through strong Hβ but lack of [O III] emission, or secure the redshifts of fainter systems through Hα detections. Highly-multiplexed NIRSpec spectroscopy offers an alternate route to discovering the faintest pristine galaxies out to z=10, without requiring deep medium-band/MIRI imaging to identify secure candidates.

We present observational evidence of three massive, accreting black holes in the z = 5.0167 galaxy J0148-4214 from JWST/NIRSpec-IFU spectroscopy. The black holes are revealed through broad H α emission (FWHM = 430–2920 km/s) without a forbidden-line counterpart in the bright [O III ] doublet. Channel maps of the asymmetric central H α profile isolate two spatially distinct broad-line regions (BLRs), separated by 190 ± 40 pc, while a third BLR is found in the galaxy outskirts with a projected separation of 1.7 kpc. We discuss whether this emission could be due to supernovae, shocks, winds, or massive stars, but find the BLR origin most likely. Using single-epoch virial relations, we estimated black hole masses of log( M • / M ⊙ ) = 7.9 ± 0.4 (primary), 5.8 ± 0.5 (secondary), and 6.3 ± 0.5 (third off-nuclear). We argue that the two central black holes will likely rapidly merge, with a simple dynamical friction time estimate of the order of ≲700 Myr. Assuming that the third off-nuclear black hole is also in the process of sinking towards the centre, it will likely lead to a second merger, and we investigated the detection probability of such mergers with LISA. Alternatively, the third black hole may be the result of a previous central three-body interaction or a gravitational recoil, where our observations would provide evidence that such black holes may retain their accretion discs and BLRs even in the aftermath of such extreme dynamical interactions. The possible discovery of a black hole triplet at high redshifts, together with other recent results on distant black hole pairs, indicates that multiple massive black hole systems were likely common in the early Universe. Our results highlight the importance of IFU observations for the detection of massive black hole multiplets in distant galaxies, the progenitors of massive black hole mergers that may be detected with next-generation gravitational wave observatories.

We present an analysis of a sample of 36 Little Red and Blue Dots (LRDs and LBDs) at 2.26<z<7.89, identified by JWST in the GOODS fields. While both categories are selected to have broad Balmer lines, both of them are extremely X-ray weak. Both classes share the same location on various diagnostic diagrams, consistent with AGN excitation (with some deviations which can be ascribed to low metallicity), although their weak HeII emission suggests a generally softer ionizing spectrum than ordinary AGN. LRDs display Lyα emission stronger than normal star-forming galaxies, and with a broad component consistent with the broad component of Hα. Overall, these findings indicate that LRDs and LBDs are both powered by growing black holes and their ionizing radiation escapes to ionize the surrounding interstellar medium (ISM). The broad Balmer lines (Hα_b and Hβ_b) have different apparent properties: LBDs have EW(Hα_b) and Hα_b/Hβ_b broadly consistent with normal AGN, while LRDs have higher values of both quantities, although still in the tail of the quasars distribution. LRD models in which a gas envelope completely encases the black hole, are inconsistent with these results – these scenarios need modification to include clumpiness, or a (classical) equatorial geometry, letting ionizing photons reach the ISM. The different broad Balmer properties imply that LBDs cannot simply be LRDs with more galaxy contribution. Scenarios in which LRDs are simply dust-obscured LBDs seem broadly consistent with the observations. Finally, these results indicate that LRDs' bolometric luminosities estimated assuming isotropic emission and complete covering by the absorber are inadequate. The few X-ray-detected LRDs suggest no deviation from the standard AGN bolometric corrections, once absorption is accounted for.

Recent JWST/NIRSpec observations have revealed high-z star-forming galaxies depart from the Fundamental Metallicity Relation (FMR), yet the z = 0 FMR has not been well-characterized in the low-mass regime (log(M_⋆/M_⊙) ≲ 9) for an appropriate comparison of low- and high-z systems. We attempt to rectify this limitation through a meta-analysis, providing a local, observational comparison for future high-z FMR studies. We analyzed common FMR fitting methods for ∼ 700 [OIII]λ4363 emitters with log(M_⋆/M_⊙) ≲ 9 at z ∼ 0. We find no evidence of the FMR below log(M_⋆/M_⊙) ≲ 9 through any method, suggesting that slowly-evolving, quasi-steady state gas reservoirs are not yet established. We simultaneously find a weak positive correlation between metallicity and star formation, and that these systems are gas-rich with substantial diversity in effective yields (y_ eff) spanning ∼ 3 dex. We demonstrate increasing y_ eff correlates with decreasing FMR offsets, which in the context of the analytical and non-equilibrium gas models of Dalcanton et al. (2007), indicates a scenario where star formation bursts rapidly return and eject metals from the ISM before subsequent gas-balancing. Pristine infall diluting the ISM metal-content cannot lead to the y_ eff diversity we measure, and thus is not the primary process behind FMR deviations. Our results suggest low-M_⋆ systems, regardless of redshift, depart from a steady-state gas reservoir shaping the canonical FMR, in which metallicity variations are primarily driven by star formation and enriched outflows. With this characterization, we demonstrate z ≳ 3 [OIII]λ4363 systems are indeed more metal-poor than z ∼ 0 counterparts (Δ12+log(O/H) = 0.3 dex) at fixed M_⋆.

Context . Collisional ring galaxies are a rare class of interacting systems, comprising only ∼0.01% of galaxies in the local Universe. Their formation is typically attributed to a head-on collision of a massive galaxy with a compact satellite (intruder), triggering density waves propagating outwards that produce the characteristic ring morphology. Here, we report the discovery and detailed analysis of GS18660, the most distant ring galaxy known to date, at z = 3.076, based on JWST data obtained within of the GA-NIFS programme. Aims . This work aims to characterise the physical and dynamical properties of GS18660 and shed light on the formation of its ring. Specifically, we analysed the ionised gas properties, stellar populations, and gas kinematics of the system, and used the observed geometry to constrain the timescale of the collision. Methods . Our analysis is based on NIRSpec integral field spectrograph (IFS) data, including low-resolution ( R ∼ 100) spectroscopy covering 0.6–5.3 μ m (∼0.2–1.3 μ m rest-frame), and high-resolution ( R ∼ 2700) spectroscopy covering 1.66–3.17 μ m (0.4–0.8 μ m rest-frame). Multi-wavelength techniques (e.g. emission line diagnostics, full spectral fitting, and gas dynamics) were applied to derive nebular gas conditions and stellar population properties. Results . Gas kinematic analysis reveals that GS18660 exhibits a rotating disc component with an additional radial expansion velocity of ∼200 km s −1 , consistent with a propagating collisional wave. Nebular line diagnostics indicate an intense star formation (star formation rate SFR ∼100 M ⊙ yr −1 ) along the ring and in the nucleus. Stellar population analysis shows that the most recent star formation episode, occurring within the last ≈50 Myr, predominantly took place in the ring. We also identify a close companion, the intruder galaxy responsible for the collision, moving away with a relative velocity of ∼425 km s −1 . Conclusions . The evidence favours a collisional origin for the ring in GS18660, though the presence of a recently formed bar (and hence a resonance ring) cannot be completely excluded. This discovery provides a unique window to the physics of galaxy interactions and the rapid assembly of stellar structures in the early Universe.