GA-NIFS

List of publications

Brief description of each publication

36) GA-NIFS: A smouldering disk galaxy undergoing ordered rotation at z=4.26 , Jones et al. (2026b) ADS link

Rotating galaxies with relaxed gaseous disks have been discovered across cosmic time, from the local Universe to high redshift (z>4). But few such sources have been confirmed at z>4, making them a precious sample to examine the conditions required for such ordered kinematics in an early, more chaotic Universe. One of the best examples of this sample is the galaxy J0817g (z=4.26), which shows remarkably clear rotation in ALMA [CII] data. We present recent JWST/NIRSpec IFU data (R~2700) of J0817g, which we combine with archival ALMA [CII] observations to place constraints on its ISM conditions and morpho-kinematics. From a combination of line ratios, we find a high gas-phase metallicity (~80% solar), high fraction of obscured star formation, low ionisation (compared to other high-redshift galaxies observed with JWST), and no significant evidence for AGN (based on the WHAN diagnostic). Dynamical modelling with 3DBarolo reveals nearly identical rotation in Hα and [CII], but with a higher velocity dispersion in the former. Altogether, we suggest that this is a 'smouldering' galaxy, where past star formation resulted in significant chemical enrichment (i.e., Z_gas and M_dust), but the current activity is low (i.e., lower ionisation parameter and lack of starburst activity).

The [CII] and Hα emission shows remarkably similar morphology (M0), line of sight velocity (M1), and velocity dispersion (M2). Fitting each data cube with 3DBarolo results in very similar rotation curves and a slightly higher Hα velocity dispersion (but < 3σ discrepant)

35) GA-NIFS & JADES: Confirmation of pristine gas near GN-z11 , Übler et al. (2026) ADS link

In this letter, we report the detection of ionised hydrogen (Hγ₄₃₄₂) in a region about 3 pkpc (projected) North-East from the z~10.6 galaxy GN-z11, where line emission compatible with doubly ionised helium (HeIIλ1640) had previously been found. Our new G395H data confirm the authenticity of the previous detection, at a redshift of z_Hγ = 10.5862 ± 0.0003. No metal lines are detected in our observations spanning λ_rest = 0.25–0.45 μm. We derive a 3σ upper limit on the gas phase metallicity of 12+log(O/H)<7.0 (Z_gas < 0.02 Z_⊙). Through comparison with NIRCam imaging, we constrain a lower limit on the equivalent width of EW₀(Hγ) > 350 Å. We compare our emission line constraints to model predictions and find them compatible with photoionization by PopIII stars, possibly intermixed with next-generation (PopII) stars. We infer an upper limit on the dynamical mass of M_dyn ≲ 3 × 10⁸ M_⊙. Our data provide novel support for the presence of PopIII stars nearby GN-z11, 440 Myr after the Big Bang.

34) GA-NIFS: The interplay between feedback and star formation at 3 < z < 9 probed by JWST/NIRSpec IFU , Ulivi et al. (2026) ADS link

We present a spatially resolved study of six galaxies at 3 < z < 9 observed with JWST/NIRSpec low resolution (R~100), including starburst- and AGN-dominated systems. Combining stellar population histories with previously identified ionized outflows, we find evidence of recent quenching in massive galaxies (M_* > 5 × 10¹⁰ M_⊙) hosting strong AGN-driven outflows, primarily within their central 3 kpc. In contrast, lower-mass, high-redshift starburst galaxies with powerful outflows show continued growth, with no clear signs of quenching. Massive galaxies with weaker outflows likewise show no evidence of past quenching, highlighting the potential role of AGN feedback in shaping galaxy evolution in the early Universe.

32) GA-NIFS: Dissecting The Alchemised: NIRSpec/IFU reveals turbulent gas inflows in a complex system at z=10.17 , Pascalau et al. (2026) ADS link

We present the first spatially resolved study of the interstellar medium (ISM) in MACS0647-JD, a gravitationally lensed galaxy system at z=10.17, observed with JWST/NIRSpec IFU as part of the GA-NIFS programme. Combining emission-line spectroscopy with NIRCam imaging, we investigate the gas-phase metallicity, kinematics, and spatially resolved star formation histories of this system, only ~450 million years after the Big Bang.
We find two distinct stellar components with significantly different gas-phase metallicities, suggesting different chemical enrichment histories. Remarkably, the peak of nebular emission is spatially offset from the stellar continuum by ~150 pc, potentially indicating merger-triggered star formation. We also identify a region of turbulent, metal-poor gas between the two components, coinciding with strongly enhanced recent star formation. These findings suggest that gravitational interactions and the redistribution or accretion of metal-poor gas may play an important role in triggering starbursts and regulating galaxy growth in the early Universe.

Panel a): RGB image of MACS0647-JD1 obtained by superposing F115W, F200W and F444W NIRCam photometry. We overlay the field-of-view of our IFU observations (dashed square). Panel b): The star formation burstiness probes the recent versus prolonged star formation activity. The solid red rectangles correspond to the two clumps. The map shows a recent star formation enhancement in the north-east region and a less bursty SFH in the region of the more massive south-east clump. Panel c): The stellar mass density map of the system confirms the more massive nature of the two clumps, compared to other regions. Panel d) shows the spaxel-by-spaxel maps of gas-phase metallicity. Panel e) shows the intrinsic gas FWHM. The FWHM map shows two high-dispersion regions which coincide with the locations of the metal-poor gas. The `x' and `+' crosses mark the Hγ emission-line and the F444W stellar continuum centroids, respectively. Panel f): Strong-line metallicity map based. We overplot the contours of the integrated fluxes of [O II]λλ3726,3729 (teal) and [Ne III]λ3869 (fire-brick). Both the contours and the inset panels show that [Ne III] has a more compact distribution while [O II] is more extended.

31) GA-NIFS: an extended [OIII] halo around the sub-Eddington quasar J1342+0928 at z=7.54 , Trefoloni et al. (2026) ADS link

Quasars emit tremendous amounts of light as matter accretes onto supermassive black holes. Their extreme luminosities allow us to probe accretion processes deep into the epoch of reionisation. ULAS J1342+0928, at (z=7.54), is one of the most distant quasars known, shining just 700 Myr after the Big Bang. In this work, we analyse new JWST/NIRSpec IFU observations obtained in both high- and low- spectral resolution modes to characterise its rest-frame optical emission. The high-resolution data reveal a fast, marginally resolved [O III] outflow with a velocity exceeding 1500 km/s. Notably, the low-resolution data reveal the largest contiguous [O III] halo detected at the epoch of reionisation. Furthermore, we demonstrate for the first time the potential of accretion disc modelling applied to low-resolution JWST/NIRSpec data as a robust alternative to standard methods for estimating black hole masses and bolometric luminosities in high-redshift quasars. Combining these measurements, we infer an Eddington ratio of ~0.4, challenging the widespread assumption that the first luminous quasars accreted at or above the Eddington limit.

[O III] flux map from the prism BLR- and continuum-subtracted cube. The circles show the extraction regions of the [O III] spectra from the R2700 cube, which are labelled accordingly. In the inset panels, we show the R2700 BLR- and continuum-subtracted spectra together with the best-fit models for the nucleus (left) and the [O III] halo (right).

30) GA-NIFS: The highest-redshift ring galaxy possibly resulting from a head-on collision , Perna et al. (2026b) ADS link

Using JWST/NIRSpec integral-field spectroscopy, we discovered and studied GS18660, a remarkable ring galaxy at redshift z=3.076, when the Universe was only about 2 billion years old. The galaxy hosts a prominent ~3.5 kpc star-forming ring, a bright central region, and a close companion connected by faint emission, and tidal structures. Its gas is rotating but also shows substantial non-circular motions, while the stellar populations indicate a recent burst of star formation concentrated in the ring. Together, the morphology, companion, stellar populations, and complex gas kinematics favour a scenario in which the ring was produced by a recent galaxy collision. However, the data cannot completely exclude an alternative interpretation in which the ring is associated with a recently forming bar and resonances. GS18660 therefore offers a unique laboratory for studying how galaxy interactions and internal dynamical structures develop in the early Universe.

Three-colour composite image showing the environmental context of the ring galaxy GS18660 and its close companion and emitters.

29) GA-NIFS: Powerful and frequent outflows in moderate-luminosity AGN at z∼3 , Venturi et al. (2026) ADS link

In this work, we study the properties of outflows in active galactic nuclei (AGN) from the GOODS-S field, exploiting JWST NIRSpec IFU observations, tracing rest-frame optical ionised gas emission lines (e.g. [O III], Hα). Together with its twin subsample from the COSMOS field reported in a previous GA-NIFS work (Bertola et al. 2025), this constitutes the largest spatially resolved sample of AGN outflows at these redshifts to date, comprising 16 targets with outflows (out of a total of 19 AGN), and probes the unexplored regime of AGN at z ∼ 3–6 with bolometric luminosities of L_bol ∼ 10^45–46 erg/s (left panel in the figure). The incidence of ionised outflows in the GOODS-S + COSMOS GA-NIFS sample is high (>75%). We find that the outflow properties inferred for the GOODS-S + COSMOS GA-NIFS AGN sample and their relations to L_bol and SFR generally align with those observed for other spatially resolved literature samples of AGN outflows across different redshifts and AGN luminosities (central panel in the figure). Nonetheless, after accounting for any luminosity bias, our analysis suggests a cosmic evolution of the outflow properties, with higher median mass outflow rates (and possibly also mass loading factors) at higher redshifts, especially at z > 3, which indicates that AGN outflows were stronger in the early Universe than at later times, and thus potentially more capable of affecting their host galaxy (right panel in the figure).

Left: AGN bolometric luminosity L_bol versus redshift (z) for AGN from GA-NIFS and from other spatially resolved studies in the literature. The plot shows that the parameter space at z > 3 and L_bol < 10⁴⁶ erg/s had remained uncharted until the advent of GA-NIFS. Centre: AGN L_bol versus mass outflow rate Ṁ_out . Right: Redshift evolution of the mass outflow rate for sources (from both GA-NIFS and the literature) with AGN L_bol < 10⁴⁶ erg/s, matching those of our GA-NIFS targets in order to remove any luminosity bias. The blue point is the median, and the dotted horizontal segments mark the first and third quartiles of the distribution of Ṁ_out at each redshift bin. The plot indicates that the mass outflow rate increases with redshift, especially at z > 3.

28) GA-NIFS: high prevalence of dusty and metal-enriched outflows in massive and luminous star-forming galaxies at z∼3−9 , Rodríguez Del Pino et al. (2026) ADS link

We use JWST/NIRSpec integral field spectroscopy to investigate ionised outflows in 15 star-forming systems at z ∼ 3–9, comprising a total of 40 individual galaxies or spatially distinct regions, with stellar masses spanning log(M_*/M_⊙) ∼ 9.5–11. We identify outflows in 16 individual galaxies or regions across 13 of the 15 systems. We find that the outflowing gas is more dust-attenuated and metal-enriched than the interstellar medium of the host galaxy, suggesting that outflows contribute to redistributing dust and metals around galaxies. However, their generally low mass-loading factors and velocities indicate that these outflows are unlikely to significantly suppress star formation or escape into the circumgalactic medium, pointing to inefficient ejective feedback in massive galaxies during the first 2 billion years of cosmic history.

Comparison of the nebular dust attenuation (left) and metallicity (right) for the narrow and broad kinematic components in the galaxy regions in our sample identified to host ionised outflows. Symbols are colour-coded according to the redshift of the galaxies. We include values measured in other star-forming galaxies at z ∼ 6.1 − 6.2 by Crespo Gómez et al. (2025) and Marques-Chaves et al. (2026). The black dashed lines correspond to the one-to-one relation

27) GA-NIFS: AGN activity in a Lyα emitter within a triple-AGN system anchored by a passive galaxy at z=3 , Perna et al. (2026a) ADS link

Previous JWST observations had uncovered a remarkable environment around GS10578, one of the earliest known massive quenched galaxies, revealing an AGN at its centre and a second actively accreting black hole in a satellite only a few kiloparsecs away (D’Eugenio+24, Perna+25, Scholtz+26). In this work, using new JWST/NIRSpec IFU and VLT/MUSE observations, we explored its wider environment and confirmed that a nearby Lyα-emitting satellite also hosts an actively growing supermassive black hole, establishing the presence of a rare triple-AGN system within a region only a few tens of kiloparsecs across. We also investigated a second Lyα source that remains undetected in deep imaging and spectroscopy, finding evidence that its emission is powered by radiation from the neighbouring AGN rather than by its own stars. These results reveal that massive quenched galaxies can reside in surprisingly dynamic and gas-rich environments, where black-hole growth, feedback, and satellite interactions continue to shape galaxy evolution long after star formation has ceased.

Environmental context of GS10578 and its close emitters. Left: NIRCam three-colour composite image; Right: VLT/MUSE narrow-band image obtained by integrating over the Lyα line.

26) GA-NIFS: interstellar medium properties and tidal interactions in the evolved massive merging system B14-65666 at z = 7.152 , Jones et al. (2026a) ADS link

We present JWST/NIRSpec IFU observations of the z=7.152 galaxy system B14-65666, as part of the GA-NIFS survey. Line and continuum emission in this massive system (log(M_*/M_⊙)=9.8±0.2) is resolved into two strong cores surrounded by diffuse emission, as seen in recent JWST/NIRCam imaging. Each spectrum is fit with a model that consistently incorporates interstellar medium conditions (i.e. electron temperature, electron density, and colour excess, E(B−V)). The resulting line fluxes are used to constrain the gas-phase metallicity (Z_gas~20-30% solar) and Hβ-based star formation rate for each region. Common line ratio diagrams (O32-R23, R3-R2, Ne3O2-R23) reveal that each line-emitting region lies at the intersection of low- and high-redshift galaxies, suggesting low ionization and higher metallicity compared to the predominantly lower-mass galaxies studied with the JWST/NIRSpec IFU so far at z>5.5. Spaxel-by-spaxel fits reveal evidence for both narrow (FWHM <400 km/2) and broad (FWHM >500 km/s line emission, the latter of which likely represents tidal interaction or outflows. Comparison to ALMA [C II]158μm and [O III]88μm data shows a similar velocity structure, and we explore optical-far infrared diagnostics. The two core galaxies both lie on the mass-metallicity relation at z>4, but show contrasting properties (e.g. M_∗, Z_gas), suggesting distinct evolutionary pathways.

24) GA-NIFS: The highly overdense system BR1202-0725 at z∼4.7. A double AGN with fast outflows plus eight companion galaxies, Zamora et al. (2025) ADS link

Distant quasars (QSOs) are considered key actors in the evolution of the early Universe. High-redshift merging systems, containing two or more supermassive black holes (BH) surrounded by close companions, tidal bridges, and tails on kiloparsec scales, represent an expected phenomenon, as evidenced by the first spatially resolved spectroscopic observations from the James Webb Space Telescope (JWST). The study of these systems provides crucial insights for constraining key components of galaxy evolution models, enhancing our understanding of galaxy growth and the feedback effects of active galactic nuclei (AGN) throughout the history of the Universe. In this work, we present the QSO in the merging system BR1202-0725: one of the best laboratories at z~4.7. The quasar is located about 24 kpc from a submillimetre galaxy with evidence of heavily dusty BH at its center and a powerful outflow expelling ~5 × 10⁶ M⊙ of ionized gas at ~5000 km/s, comparable to outflows in luminous QSOs. Thus, they form one of the most distant close pairs of AGN known so far. Additionally, this merger is one of the most overdense fields known in the early universe formed also by the three Lyα emitters and four companion galaxies. Using JWST observations, we estimated the BH properties and characterized the interstellar medium of the system. Our goal is to investigate the physical conditions and ionizing mechanisms, as well as to assess the impact of dual black holes driving outflows at high redshift.

Left panel: Comparison of the SMG line profiles of the [OIII], Hα+[NII], and [CII] emission lines in velocity space. All line profiles are normalized to their peak value. The vertical black dotted line indicates the zero velocity at the systemic redshift of z = 4.6891 Right panel: JWST NIRSpec IFU Hα image of BR1202-0725. Dust continuum emission from ALMA in Band 7 is shown as black contours. Star symbols illustrate the position of the two Lyman-α emitters in the FoV. North is up, east is left. A logarithmic color scale is used. .

23) GA-NIFS & EIGER: A merging quasar host at z=7 with an overmassive black hole , Marshall et al. (2025) ADS link

In this work we combined JWST observations from GA-NIFS (NIRSpec IFS) and EIGER (NIRCam imaging) to study the z=7.08 quasar J1120+0641. Our emission-line maps revealed that this quasar host is undergoing a major merger with a bright companion galaxy. Through detailed quasar subtraction and SED fitting, we improved the host galaxy stellar mass measurements, which were previously overestimated due to the presence of this companion and a lack of emission line measurements. With the updated mass measurements, we find an extreme black hole-stellar mass ratio of ~63% for J1120, the most overmassive black hole ever discovered, ∼3 dex larger than expected by the local scaling relations.

Black hole–stellar mass relation showing the overmassive BH in J1120+0641 (gold).

21) GA-NIFS: Dissecting the multiple sub-structures and probing their complex interactions in the Lyα emitter galaxy CR7 at z = 6.6 with JWST/NIRSpec, Marconcini et al. (2025) ADS link

In this work, we present JWST/NIRSpec IFS observations of the Lyα emitter CR7 at z = 6.6, revealing the tight interaction between its clumpy multiple components. Low resolution PRISM data confirm a bright Lyα source and a ~3 kpc diffuse Lyα halo associated with the main galaxy CR7-A, alongside two UV-bright companions (CR7-B and CR7-C). High-resolution G395H observations uncover at least one additional companion traced by [O III]λ5007 emission and a extended ionised gas filaments connecting the systems. Spatially resolved emission-line diagnostics show elevated [O III]/Hβ ratios and tentative AGN-like ionisation in CR7-A and CR7-B, while distinct narrow and broad kinematic components reveal blueshifted and redshifted outflows in the two most massive components. Electron temperature and metallicity maps highlight strong internal gradients, suggesting gas exchange among the main components. As supported by SED-derived star-formation histories our data portray CR7 as a dynamically rich, interacting system where mergers, feedback, and ionised gas flows regulate galaxy growth in the reionisation.

Left panel: Collapsed [OIII]λ5007 emission from the high-resolution G395H data showing the multiple component structure of CR7. Right panel: SED-derived star formation history in each component of the system divided in redshift bins.

20) GA-NIFS: Mapping z≃3.5 AGN-driven ionized outflows in the COSMOS field, Bertola et al. (2025) ADS link

A key phase of galaxy evolution is the rapid transition (< 2Gyr) from early galaxy assembly at ‘cosmic dawn’ (i.e., z>6) to the so-called ‘cosmic noon’ (z~1-3), where the cosmic density of both star formation rate (SFR) and SMBH accretion rate peak. Galaxy growth is thus closely tied to AGN activity, yet little is known about the impact of AGN feedback beyond z~3, especially in the ionized gas phase. The GA-NIFS JWST/NIRSpec GTO program includes the largest sample of AGN at z~3-6 with available rest-frame optical spatially-resolved spectroscopy collected with JWST/NIRSpec/IFU (Perna+25b).
In this paper, we presented our study to characterize AGN outflows in such a sample of z~3-6 AGN selected from COSMOS to have log($L_{\rm X}$/erg/s)>44. We mapped the ionized emission of AGN (Halpha, [OIII], Hbeta, …) at sub-kpc scales and spectrally isolated the broad components tracing outflows from the gas at rest with the galaxy. We derived outflow properties from spatially-resolved and integrated spectra (e.g., velocity, outflow mass rate) and compared them with those of the galaxy and of the AGN, retrieved from dedicated SED fitting. We compared our results with literature AGN from the local Universe to earlier cosmic epochs, spanning a very broad range of AGN luminosity. To account for the very different assumptions regarding the outflow density, we made the choice of comparing our results with the literature by parameterizing this parameter while homogenizing the various collected measurements. We find that outflows observed in COS-AGNi are well consistent with the previous results in the \(\dot{M}_{\rm out}\) versus \(L_{\rm bol}\), \(\dot{E}_{\rm out}\) versus \(L_{\rm bol}\), and \(v_{\rm max}\) versus \(L_{\rm bol}\) parameter spaces and that they mostly fall close to or above previous scaling relations (Fiore+17, Bischetti+19b, Musiimenta+23). Lastly, we find no clear redshift evolution of \(\dot{M}_{\rm out} n_{\rm e} / L_{\rm bol}\) and \(\dot{E}_{\rm out} n_{\rm e} / L_{\rm bol}\) beyond \(z > 1\). In general, the trends shown by GA-NIFS AGNi at z>3 are similar to those observed at lower redshifts, suggesting that the nature of AGN feedback does not significantly evolve beyond z=3.

19) GA-NIFS: Witnessing the complex assembly of a massive star-forming system at z=5.7, Jones et al. (2025) ADS link

We present observations of the z~5.7 Lyman-break galaxy HZ10 with the JWST/NIRSpec IFU in high and low spectral resolution (G395H, spectral resolving power R~2700 and PRISM, R~100, respectively). By spatially resolving the source (spatial resolution ~0.15" or ~0.9kpc), we find three spatially and spectrally distinct regions of line emission along with one region of strong continuum emission, all within a projected distance of <10 kpc. None of the detected lines present strong evidence for AGN excitation from line diagnostic diagrams, and no high-ionisation lines are detected. Using the detected lines, we constrain the electron density (log10(n_e/cm^-3)~3) and metallicity (~0.5−0.7 solar) in each component. Spaxel-by-spaxel fits reveal a strong east-west velocity gradient and significant line asymmetries (possibly indicating tidal features or outflows). The western component features a very red UV slope (β_UV~−0.9) and significant Hα emission, suggesting an evolved population and active star formation. A comparison to high resolution (~0.3" or ~1.8kpc) [CII]158μm imaging obtained with ALMA reveals areas of dust obscuration. Altogether, these data suggest that HZ10 represents an ongoing merger, with a complex distribution of stars, gas, and dust <1 Gyr after the Big Bang.

Comparison of distribution of rest-optical continuum emission (colours and red contours on left) with line emission (colours and red contours on right). [OIII] emission is focused in three core components (HZ10-E/-C/-W), while the continuum is offset to the north.

17) GA-NIFS: A high number of dual AGN at z~3, Perna et al. (2025b) ADS link

Galaxy mergers can drive gas onto central supermassive black holes (SMBHs), forming dual active galactic nuclei (AGN). The fraction of AGN pairs provides key insights into galaxy interactions, SMBH growth, and co-evolution with their hosts. However, identifying dual AGN remains challenging due to the need for high-quality spatial and spectral data, with only a few detected at high redshifts. We estimate the fraction of dual AGN at 2 <z < 6 by analysing 16 AGN observed with JWST/NIRSpec in integral field mode as part of the GA-NIFS survey. For two targets, we include archival VLT/MUSE data to extend the search area. We identify companion galaxies and emission-line sources within the ∼20×20 kpc NIRSpec field of view, extending to ∼50 kpc with MUSE. Their spectra are analysed to determine physical and kinematic properties. We report the serendipitous discovery of a triple AGN and four dual AGN, with projected separations of 3–28 kpc. This more than doubles the number of known multiple AGN at z > 3 within these separations. The estimated fraction of multiple AGN (∼20–30%) exceeds previous observational constraints and moderately surpasses predictions from cosmological simulations (∼10%). These results demonstrate NIRSpec’s exceptional ability to detect distant dual AGN and motivate further studies to refine their occurrence across cosmic time.

[OIII] map (top-left) and integrated spectra of the dual AGN system associated with COS1638.

16) GA-NIFS: Multi-phase analysis of a star-forming galaxy at z∼5.5, Parlanti et al. (2025) ADS link

Outflows play a crucial role in galaxy evolution, shaping the galaxy mass function at the high and low mass end by expelling and heating the gas in the galaxy and suppressing star formation. Low-z studies suggest that outflows are multiphase, and now, for the first time with the advent of JWST we can observe the rest-frame optical emission line from high redshift galaxies, expand our search for ionized outflows up to the early Universe. In this work, we analyze the JWST NIRSpec/IFU data of HZ4, a main sequence, star-forming galaxy at z=5.5, which is the highest redshift star forming galaxy with a neutral outflow traced by the broad [CII] emission. These data, together with the ALMA observations allow us to characterize the properties of the different phases of the ISM. In particular we find the presence of an ionized outflow identified as a broad component in the [OIII] and Hα emission lines. The outflow is launched by a region hosting a burst of star formation, with the mass outflow rate of the ionized phase being smaller than the neutral one. These two phases are expelling from the star forming region the same amount of gas that is converted into stars. This dataset allows us to study for the first time the properties multiphase properties of a star-formation driven outflow at z~5.5.

Top left and central panels: flux and velocity of the [OIII] narrow component. Bottom left and central panels: Flux and velocity of the outflow component, green contours show the narrow [OIII] flux. Right panel: Comparison between the ionized and neutral mass outflow rate color-coded by redshift. The pink star marks the measurements for HZ4 from this work. The turquoise circles are the local ULIRGs, the triangle, pentagon, diamond, and square display the results obtained for local and high-z AGN. The black dashed line represents the 1:1 relation

15) GA-NIFS: A galaxy-wide outflow in a Compton-thick mini-BAL quasar at z = 3.5 probed in emission and absorption, Perna et al. (2025a) ADS link

In this paper, we examine GS133, a Compton-thick quasar at z=3.5, utilising JWST NIRSpec integral field spectroscopy (IFS) and archival Very Large Telescope (VLT) data with integration times of 1 hour and 40 hours, respectively. Our optical emission-line analysis reveals a rotating disk accompanied by a galaxy-wide bi-conical outflow exhibiting velocities up to 1000 km/s. Additionally, ultraviolet absorption features disclose high-velocity outflow components reaching -1900 km/s, indicative of a mini-broad absorption line (mini-BAL) system.
Through photoionisation and kinematic modelling, we infer partial mixing of emitting and absorbing gas clouds within the outflow on kiloparsec scales. The inferred outflow mass-loading factor and kinetic coupling efficiency indicate significant AGN feedback on galactic scales. These results demonstrate the complex interplay between AGN activity, star formation, and the ISM, emphasising the transformative capabilities of JWST for exploring feedback in high-redshift galaxies.

Left panels: MOKA3D model of the outflow in GS133. Right panels: moment maps from NIRSpec data and from the MOKA3D model.

14) GA-NIFS: JWST/NIRSpec IFS view of the z~3.5 galaxy GS5001 and its close environment at the core of a large-scale overdensity, Lamperti et al. (2024) ADS link

In this paper, we present JWST/NIRSpec IFS observations of the galaxy GS5001 at redshift z = 3.47, the central member of a candidate protocluster in the GOODS-S field. We analysed the spatially resolved ionised gas kinematics and interstellar medium properties, including obscuration, gas metallicity, excitation, ionisation parameter, and electron density. In addition to the main galaxy (GS5001), the NIRSpec FoV covers a close companion in the south, with three sub-structures, and another source in the north. Optical line ratio diagnostics indicate star formation ionisation and electron densities of ∼500 cm$^{-3}$ across all sources in the FoV. We find higher gas-phase metallicity in the main galaxy is 12+log(O/H) = 8.45 ± 0.04, than in the companions (12+log(O/H) = 8.34 ‑ 8.42), consistent with the mass-metallicity relation at z ∼ 3. We find peculiar line ratios (high [N II]/Hα and low [O III]/Hβ ) in the northern part of GS5001. These could be attributed to either higher metallicity, or to shocks resulting from the interaction of the main galaxy with the northern source. Moreover, we identify a spatially resolved outflow in the main galaxy, with an extension of about 3 kpc, maximum outflow velocities of ∼400 km/s, a mass outflow rate of 23 ± 5 M⊙/yr, and a mass loading factor of 0.23. These properties are compatible with star formation being the driver of the outflow. Our analysis of these JWST NIRSpec IFS data therefore provides valuable, unprecedented insights into the interplay between star formation, galactic outflows, and interactions in the core of a z ∼ 3.5 candidate protocluster.

Identification of galaxies and structures around GS5001. Left: NIRCam three-color image of GS5001. Middle: HST/ACS F775W band image with contours of the NIRSpec [OIII] emission in red. Right: NIRSpec [OIII] flux map with contours of the HST/ACS F775W emission in black. Blue and green regions mark the different components identified in the [OIII] map.

13) GA-NIFS: An extremely nitrogen-loud and chemically stratified galaxy at z∼5.55, Ji et al. (2024) ADS link

Recent JWST observations revealed several galaxies with extreme nitrogen enhancements in the early Universe, whose enrichment mechanisms remain debated. In this work, we present the chemical abundance pattern of GS_3073, a galaxy at z=5.55 hosting an ​``overmassive'' active black hole, by leveraging the detection of about 40 emission lines from JWST/NIRSpec IFU observations and ground-based (VLT/VIMOS) data. By using rest-frame UV emission lines, which trace high-density ($\sim 10^5~{\rm cm}^{-3}$) and highly ionized gas, we derive an abundance ratio of $\rm log(N/O) = 0.46^{+0.12}_{-0.09}$. At an estimated metallicity of $0.2~Z_{\odot}$, this is the most extreme nitrogen-rich galaxy found by JWST thus far. In comparison, the relative carbon abundance of GS_3073 is not significantly higher than those in local galaxies and stars with similar metallicities. We also find evidence of Fe enrichment in GS_3073. Overall, the chemical abundance pattern of GS_3073 is compatible with enrichment by super-massive stars, ejecta from asymptotic giant branch (AGB) stars, or winds from Wolf-Rayet (WR) stars. Interestingly, when using optical emission lines which trace low-density and low-ionization gas, we find a sub-solar N/O ratio, consistent with local galaxies at the same metallicity. We interpret the difference in N/O derived from UV lines and optical lines as evidence for a stratified system, where the inner and denser region is both more chemically enriched and more ionized. Taking this luminous, well-studied system as a benchmark, our results suggest that nitrogen enhancement in high-$z$ galaxies is confined to the central, dense, and highly ionized regions, while the bulk of the galaxy evolves more normally.

Relation between N/O and O/H measured from different systems. We used open symbols to represent all $z\sim 0$ sources except the nitrogen-loud galaxy Mrk 996. The colored symbols represent nitrogen-loud galaxies confirmed by JWST/NIRSpec observations. The red pentagon represents the fiducial abundances we estimated for GS_3073, where N/O is estimated from rest-frame UV emission lines originating in a high-density region. The red square corresponds to the fiducial abundances we estimated based on rest-frame optical emission lines, which likely originate in a low-density region. The significantly different N/O ratios of the high-density region and the low-density region indicate a strong chemical stratification in GS_3073.

12) A fast-rotator post-starburst galaxy quenched by supermassive black-hole feedback at z=3, Francesco D'Eugenio et al. (2023) ADS link

There is compelling evidence that the most massive galaxies in the Universe stopped forming stars due to the time-integrated feedback from their central super-massive black holes (SMBHs). However, the exact quenching mechanism is not yet understood, because local massive galaxies were quenched billions of years ago. We present JWST/NIRSpec integral-field spectroscopy observations of GS-10578, a massive, quiescent galaxy at redshift $z = 3.064 \pm 0.002$. From the spectrum we infer that the galaxy has a stellar mass of $M_\star = 1.6 \pm 0.2 \times 10^{11} \mathrm{M}_\odot$ and a dynamical mass $M_\mathrm{dyn} = 2.0 \pm 0.5 \times 10^{11} \mathrm{M}_\odot$ . Half of its stellar mass formed at $z = 3.7–4.6$, and the system is now quiescent, with an upper limit on the current star-formation rate $SFR < 19 \mathrm{M_\odot \, yr^{-1}}$. We detect ionised- and neutral-gas outflows traced by $\mathrm{[O\,\scriptsize{iii}]}$ emission and $\mathrm{Na\,\scriptsize{I}}$ absorption. Outflow velocities reach $v_\mathrm{out} \approx 1,000 \mathrm{km\, s^{-1}}$, comparable to the galaxy escape velocity. GS-10578 hosts an Active Galactic Nucleus (AGN), evidence that these outflows are due to SMBH feedback. The outflow rates are 0.14–2.9 and 30–100 $\mathrm{M_\odot\,yr^{−1}}$ for the ionised and neutral phases, respectively. The neutral outflow rate is higher than the SFR, hence this is direct evidence for ejective SMBH feedback, with mass-loading capable of interrupting star formation by rapidly removing its fuel. Stellar kinematics show ordered rotation, with spin parameter $\lambda_{R_\mathrm{e}} = 0.62\pm0.07$, meaning GS-10578 is rotation supported. This study shows direct evidence for ejective AGN feedback in a massive, recently quenched galaxy, thus helping to clarify how SMBHs quench their hosts. The high value of $\lambda_{R_\mathrm{e}}$ implies that quenching can occur without destroying the stellar disc.

11) GA-NIFS: NIRSpec reveals evidence for non-circular motions and AGN feedback in GN20, Übler et al. (2024b) ADS link

In this paper, we present rest-frame optical data of the 𝑧 ∼ 4 sub-millimeter galaxy GN2. The H𝛼 emission is asymmetric and clumpy and extends over a projected distance of more than 15 kpc. To first order, the large-scale ionised gas kinematics are consistent with a turbulent (𝜎 ∼ 90 km/s), rotating disc (𝑣rot ∼ 500 km/s), congruent with previous studies of its molecular and ionised gas kinematics. However, we also find clear evidence for non-circular motions in the H𝛼 kinematics. We discuss their possible connection with various scenarios, such as external perturbations, accretion or radial flows. In the centre of GN20, we find broad line emission (FWHM ∼ 1000−2000 km/s) in the H𝛼+[NII] complex, suggestive of fast, AGN-driven winds or, alternatively, of the broad-line region of an active black hole. Elevated values of [NII]𝜆6583/H𝛼 > 0.4 and EW(H𝛼) > 6 Å throughout large parts of GN20 suggest that feedback from the active black hole is able to photo-ionise the interstellar medium. Our data corroborates that GN20 offers a unique opportunity to observe key processes in the evolution of the most massive present-day galaxies acting in concert, over 12 billion years ago.

10) GA-NIFS: the interplay between merger, star formation and chemical enrichment in MACS1149-JD1 at z=9.11 with JWST/NIRSpec, Marconcini et al. (2024) ADS link

We present JWST/NIRSpec integral-field spectroscopy observations of the z~9.11 lensed galaxy MACS1149-JD1. The data was obtained with both the G395H grating (R∼2700) and the prism (R∼100). This target shows a main elongated UV-bright clump and a secondary component detected in continuum emission at a projected distance of 2 kpc. The R2700 data trace the ionised-gas morpho-kinematics in between the two components, showing an elongated emission mainly traced by [O III]λ5007. We spatially resolve [OII]λλ3726,3729, [OIII]λλ4959,5007, and [OIII]λ4363, which enable us to map the electron density (ne∼1.0 × 10³ cm^-3), temperature (Te ∼ 1.6 × 10⁴ K), and direct-method gas-phase metallicity (-1.2 to -0.7 dex solar). A spatially resolved full-spectrum modelling of the prism indicates a north-south gas metallicity and stellar age gradient between the two components. We found 3-σ evidence of a spatially resolved anti-correlation of the gas-phase metallicity and the star formation rate density, which is likely driven by gas inflows, enhancing the star formation in JD1. We employ high-z sensitive diagnostic diagrams to rule out the presence of a strong AGN in the main component. These findings show the unambiguous presence of two distinct stellar populations, with the majority of the mass ascribed to an old star formation burst, as suggested by previous works. We disfavour the possibility of a rotating-disc nature for MACS1149-JD1 and instead favour a merger event that has led to a recent burst of star formation in two separate regions, as supported by high values of [O III]λ5007/Hβ, ionised gas velocity dispersion, and gas-phase metallicity.

From left to right: JWST NIRSpec G395H data cube collapsed over the total [O III]λ5007 emission line (left) and a zoom-in centred on JD1 (middle). Black circles mark the position of the North and South components in JD1. Yellow filled circles represent the fiducial PSF size. The right panel shows the gas-phase metallicity map derived via SED fitting, showing higher metal content in JD1-N. Black contours are arbitrary [O III]λ5007 flux levels. The black cross marks the position of the [OIII]λ5007 line peak.

9) GA-NIFS: The core of an extremely massive proto-cluster at the Epoch of Reionization probed with JWST/NIRSpec, Arribas et al. (2024) ADS link

These GA-NIFS observations reveal ten new galaxies at z~ 6.9 in the surroundings of SPT0311-58. The implied large number density ($\phi$ ~ 10$^{4}\ $Mpc$^{-3}$) and the wide spread in velocities confirm that SPT0311-58 is at the core of a protocluster immersed in a very massive dark-matter halo of ~(5 $\pm$ 3) $\times$ 10$^{12}$ M$_{\odot}$sun, and therefore represents the most massive protocluster ever found at the epoch of reionisation (EoR, see Figure below). We also studied the dynamical stage of this protocluster core and find that it is likely not fully virialised and that most of the galaxies are gravitationally bound to the dark matter halo.
The galaxies in the system exhibit a wide range of properties and evolutionary stages. Detailed spatially resolved spectroscopy of the East galaxy reveals the early phases of stellar assembling at very high-z, showing inhomogeneities in the ISM properties at subkiloparsec scales, deviations from regular rotation, elevated turbulence, and a metallicity gradient that can be explained by accretion of low metallicity gas from the intergalactic medium. We also find evidence of minor mergers.

Position of SPT0311-58 in the halo mass — redshift plane (red dot), together with a compilation of protoclusters observed at z > 2, and a set of simulations for the most massive protoclusters (Lim+2021,2024). The figure shows the extreme mass of SPT0311-58 compared to other observed proto-clusters at EoR. It also illustrates the difficulty of TNG simulations to predict a rare system like SPT0311-58, as a consequence of their limited simulated volume. The position of SPT0311-58 can be reproduced by FLAMINGO simulations (Schaye+23) with larger box sizes.

8) GA-NIFS: JWST discovers an offset AGN 740 million years after the big bang, Übler et al. (2024) ADS link

A surprising finding of recent studies is the large number of Active Galactic Nuclei (AGN) associated with moderately massive black holes (log(M•/M⊙) ∼ 6 − 8), in the first billion years after the big bang (z > 5). In this context, a relevant finding has been the large fraction of candidate dual AGN, both at large separations (several kpc) and in close pairs (less than a kpc), likely in the process of merging. Frequent black hole merging may be a route for black hole growth in the early universe; however,previous findings are still tentative and indirect. We present JWST/NIRSpec-IFU observations of the galaxy system ZS7 at z = 7.15 in which we find evidence for a log(M•/M⊙) ∼ 7.7 accreting black hole, as traced by a broad component of Hβ emission, associated with the Broad Line Region (BLR) around the black hole. This BLR is offset by 620 pc in projection from the centroid of strong rest-frame optical emission, with a velocity offset of ∼40 km/s. The latter region is also characterized by (narrow) nebular emission features typical of AGN, hence also likely hosting another accreting black hole, although obscured. We exclude that the offset BLR is associated with Supernovae or massive stars, and we interpret these results as two black holes in the process of merging. This finding may be relevant for estimates of the rate and properties of gravitational-wave signals from the early universe that will be detected by future observatories like LISA.

Top left: Colour-composite image of ZS7 and its immediate environment created using public NIRCam data from the PRIMER programme (PI: James Dunlop). The approximate NIRCam PSF is indicated by the white filled (F200W, ∼0.06") and open (F444W, ∼0.14") circles. The effective NIRSpec-IFU field of view (FOV) is indicated by the dashed white box. Top right: Zoom-in on the environment of ZS7. The colour scale shows a line map of [O III]λ5007, where we indicate the positions of two faint companions at the same redshift with dashed grey circles. The centroids of the [O III]λ5007 emission and the BLR emission are indicated by a white plus and a golden star. The approximate NIRSpec PSF at 4 μm is indicated by the white circle. The centroid of the [O III]λ5007 emission coincides with the NIRCam F200W emission, while the BLR location coincides with the F444W emission, reflected in the colour gradient in the NIRCam false-colour image.
Bottom: Zoom-in on the spectra extracted from a single spaxel at the [O III]λ5007 centroid position (left) and at the BLR location (right). We show our full fit in blue, with narrow emission lines in green and the BLR component in purple. At the BLR location, the broad Hβ emission is evident, while the [O III]λλ4959,5007 emission is narrow at all locations.

7) GA-NIFS: co-evolution within a highly star-forming galaxy group at z=3.7 witnessed by JWST/NIRSpec IFS, Rodríguez Del Pino et al. (2023) ADS link

GS4891 is a massive, highly star-forming galaxy part of a system of at least three galaxies at z~3.7, together with a system at the north GS4891_n and GS28356. NIRSpec/IFS observations have revealed internal substructure in GS4891 in the form of star-forming clumps (C1 and C2) as well as a complex interplay of interactions and internal feedback within the group. Analyses of the rest-frame optical emission lines have shown a clear gradient of more than 0.2 dex in the gas metallicity from the south to the north-west of the most-massive system (GS4891), suggesting ongoing accretion of low-metallicity gas from the inter-galactic medium that would be contributing to the mass-assembly of the system. The even higher gas metallicity in the lower-mass companion at the north (GS4891_n) also suggests that the accretion of low-metallicity gas is favored in the most-massive system, a scenario that would lead to a different evolution in the metallicity of satellites and centrals at high redshift. The gas kinematics of the most-massive galaxy are consistent with rotation in a dark-matter dominated system. Moreover, this galaxy is host to a metal-enriched, nuclear ionized outflow that reaches up to ~1.2 kpc and could be contributing to the observed metallicity gradient.

5) GA-NIFS: JWST/NIRSpec IFU observations of HFLS3 reveal a dense galaxy group at z∼6.3, Jones et al. (2024) ADS link

Massive, starbursting galaxies in the early Universe represent some of the most extreme objects in the study of galaxy evolution. One such source is HFLS3 (z∼6.34), which was originally identified as an extreme starburst galaxy with mild gravitational magnification (μ∼2.2). Here, we present new observations of HFLS3 with the JWST/NIRSpec IFU in both low (PRISM/CLEAR; R∼100) and high spectral resolution (G395H/290LP; R∼2700), with high spatial resolution (∼ 0.1") and sensitivity. Thanks to the combination of the NIRSpec data and a new lensing model with accurate spectroscopic redshifts, we find that the 3"×3" field is crowded, with a lensed arc (C, z=6.3425±0.0002), two galaxies to the south (S1 and S2, z=6.3592±0.0001), two galaxies to the west (W1, z=6.3550±0.0001; W2, z=6.3628±0.0001), and two low-redshift interlopers (G1, z=3.4806±0.0001; G2, z=2.00±0.01). We present spectral fits and morpho-kinematic maps for each bright emission line (e.g., [OIII]λ5007, Hα, [NII]λ6584) from the R2700 data for all sources except G2 (whose spectral lines fall outside the observed wavelengths of the R2700 data). From a line ratio analysis, the galaxies in component C are likely powered by star formation, while we cannot rule out or confirm the presence of AGN in the other high-redshift sources. We perform gravitational lens modelling, finding evidence for a two-source composition of the lensed central object and a comparable magnification factor (μ=2.1-2.4) to previous work. The projected distances and velocity offsets of each galaxy suggest that they will merge within the next∼1 Gyr. Finally, we examine the dust extinction-corrected SFRHα of each z > 6 source, finding that the total star formation (460±90M⊙ yr−1, magnification-corrected but not accounting for AGN contamination) is distributed across the six z∼6.34-6.36 objects over a region of diameter∼11 kpc. Altogether, this suggests that HFLS3 is not a single starburst galaxy, but instead is a merging system of star-forming galaxies in the Epoch of Reionization.

Integrated emission of the HFLS3 field, using two illustrative wavelength ranges: redshifted Hα for z ∼ 6.34 for the R2700 cube (λobs = 4.79954 − 4.84467 μm, left panel) and the approximate wavelength range of HST/WFC3 F160W for the R100 cube (λobs = 1.4 − 1.6 μm; right panel). The adopted source masks are shown with white boundaries. North is up and east is to the left.

4) GA-NIFS: The ultra-dense, interacting environment of a dual AGN at z~3.3 revealed by JWST/NIRSpec IFS, Perna et al. (2023) ADS link

This paper explores the intriguing environment of LBQS 0302−0019, a blue QSO at z~ 3.3. This target resides in a dynamic neighborhood that includes an obscured AGN companion and multiple satellite galaxies, all within a projected distance of 30 kpc. Using the JWST NIRSpec IFS, we obtained high-resolution observations that provided unprecedented insights into this system. Our work involved developing a novel procedure to correct for spurious oscillations in the NIRSpec spectra and employing advanced decomposition tools to differentiate the quasar from its host galaxy. Our findings revealed a complex interplay of various components within the QSO environment. We identified a rotating gas disk and a high-velocity ionized outflow within the QSO host galaxy. Additionally, we detected eight companion objects, including the second, obscured AGN and five previously unknown companions. These discoveries underscore the significant role of mergers in triggering AGN and driving the rapid growth of SMBHs in the early Universe.

Original (top) and PSF-subtracted (bottom) images of the QSO LBQS 0302−0019 and its close neighbouring galaxies as observed from ground-based telescopes and JWST/NIRSpec IFS.

3) GA-NIFS: Black hole and host galaxy properties of two z ≃ 6.8 quasars from the NIRSpec IFU, Marshall et al. (2023) ADS link

In our GA-NIFS program, we have observed a sample of six quasars at z > 6. In this paper we present our results from the first two quasars observed, DELS J0411–0907 at z = 6.82 and VDES J0020–3653 at z = 6.86. By observing the Hβ, [OIII]λλ4959, 5007, and Hα emission lines in these high-z quasars for the first time, we measured accurate black hole masses, MBH = 1.85×10$^9$ $M_{\odot}$ and 2.9x10$^9$ $M_{\odot}$, corresponding to Eddington ratios of 0.8 and 0.4 for DELS J0411–0907 and VDES J0020–3653, respectively. These provide a key comparison for existing estimates from the more uncertain MgII line.
We performed quasar–host decomposition using models of the quasars’ broad lines to study the underlying host galaxies, measuring their star formation rates, excitation mechanisms, and dynamical masses. DELS J0411–0907 and VDES J0020–3653 both lie above the local black hole–host mass relation, and are consistent with the existing observations of z~6 quasar host galaxies with ALMA. We also discovered that these quasars are undergoing galaxy-galaxy mergers, with multiple companion galaxies surrounding each of the quasars. We detected ionised outflows in [OIII] and Hβ from both quasars, with mass outflow rates much larger than their host star formation rates. This work highlights the exceptional capabilities of the JWST NIRSpec IFU for observing quasars in the early Universe.

The extended [OIII] emission surrounding DELS J0411–0907 (left) and VDES J0020–3653 (right). The quasars are located at the blue cross, with their hosts the blue circle. Merging companion galaxies are the other ellipses.

2) GA-NIFS: A massive black hole in a low-metallicity AGN at z ∼ 5.55 revealed by JWST/NIRSpec IFS, Übler et al. (2023) ADS link

In this paper, we present rest-frame optical data of the compact z = 5.55 galaxy GS_3073. The galaxy's prominent broad components in several hydrogen and helium lines and a detection of a large equivalent width of He IIλ4686, EW(He II) ∼20 Å, unambiguously identify it as an active galactic nucleus (AGN). We measure a gas phase metallicity of Zgas/Z⊙∼0.21, which is lower than what has been inferred for both more luminous AGN at a similar redshift and lower redshift AGN. We empirically show that classical emission line ratio diagnostic diagrams cannot be used to distinguish between the primary ionisation source -AGN or star formation- for systems with such low metallicity, though different diagnostic diagrams involving He IIλ4686 prove useful, independent of metallicity. We measure the central black hole mass to be log(MBH/M⊙)∼8.2 ± 0.4 based on the luminosity and width of the broad line region of the Hα emission. While this places GS_3073 at the lower end of known high-redshift black hole masses, it still appears to be overly massive when compared to its host galaxy's mass properties. We detected an outflow with a projected velocity ≳700 km/s and inferred an ionised gas mass outflow rate of about 100 M⊙/yr, suggesting that one billion years after the Big Bang, GS_3073 is able to enrich the intergalactic medium with metals.

Synergies with other JWST programs