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H. Übler

Publications and source records attributed to H. Übler.

At least 19 recordsLinked to original sources

GA-NIFS: high prevalence of dusty and metal-enriched outflows in massive and luminous star-forming galaxies at $z\sim3-9$

We present a search for and characterization of ionized outflows in 15 star-forming systems at $z\sim3-9$ with no evidence of Active Galactic Nuclei (AGN), observed with JWST/NIRSpec IFU as part of the GA-NIFS program. The targets often show satellites and complex substructure, from which we isolate 40 galaxies/regions. The sample probes the high-mass end of the galaxy population, with most sources having log$_{10}$~(M$_\star$/M$_\odot$)=$9.5-11$, extending previous studies on high-z star formation driven outflows that mainly focused on lower-mass galaxies. Using the [OIII]5007 and H$α$ emission lines, we identify broad kinematic components consistent with galactic outflows in 14 galaxies/regions. We find that the outflowing gas is more dust attenuated (by $A_{\rm V}$$\sim0.59$ mag on average) and metal-enriched (0.13 dex) than the interstellar medium (ISM) of the host galaxies, but its velocities are insufficient to escape the galaxies and reach the circumgalactic medium, suggesting that outflows mainly redistribute dust and metals around their hosts. The outflows identified in this study display velocity dispersions within $σ_{\rm out}=130-340$~km~s$^{-1}$ and outflow velocities $v_{\rm out}=170-600$~km~s$^{-1}$, and, when combined with less luminous and less massive star-forming galaxies from previous works, reveal a statistically significant correlation between $v_{\rm out}$ and star formation rate (SFR). The typically low mass-loading factors ($η=\dot{M}_{\rm out}/SFR$$\leq1$, in 9 out of 14 the outflows) indicate that these outflows do not strongly suppress star formation. Overall, our results suggest that ejective feedback via ionized outflows is inefficient in massive, luminous star-forming galaxies within the first 2 Gyr of the Universe.

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Dissecting the Obscured Core of GN20: an Active Galactic Nucleus Outshone by Young Stars

We investigate the relative contributions of star formation and AGN activity to the total energy budget of GN20, one of the most luminous dusty star-forming galaxies known at $z>4$, through spatially resolved spectral energy distribution decomposition. We perform Bayesian SED fitting with CIGALE on two spatially distinct apertures: the nuclear core (r=0.14", $\sim$1kpc physical) and the full galaxy (r=1.4", 9.9 kpc), combining JWST/NIRCam and MIRI broadband imaging, JWST/NIRSpec PRISM IFU pseudo-continuum photometry spanning 42 wavelength bins across rest-frame $0.12$--$1.05μ$m, and archival HST and millimeter interferometry data from NOEMA and PdBI. The integrated SED is dominated by stellar-heated dust, with only a marginal AGN contribution at galaxy-wide scales ($f_\mathrm{AGN}^\mathrm{int}=0.09\pm0.02$). The nuclear core, however, requires a significant AGN component ($f_\mathrm{AGN}=0.34\pm0.05$) to account for a mid-infrared excess at rest-frame $\sim$2.5--3.6$μ$m characteristic of AGN-heated torus dust. The AGN accounts for $\sim34\%$ of the nuclear infrared luminosity but only $\sim9\%$ of the total integrated $L_\mathrm{IR}$, explaining its weak signature in integrated diagnostics and its consistency with existing upper limits from Spitzer spectroscopy. The inferred black hole mass places GN20 within the local $M_\mathrm{BH}$--$M_\mathrm{bulge}$ relation at the Eddington limit, and in the overmassive regime at sub-Eddington accretion rates, suggesting early and rapid black hole assembly concurrent with the dominant starburst. GN20 exemplifies a class of systems where nuclear-scale SED decomposition, enabled by the angular resolution and infrared sensitivity of JWST, is the only means to uncover a buried AGN overwhelmed by galaxy-wide star formation.

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GA-NIFS: The interplay between feedback and star formation at 3 < z < 9 probed by JWST/NIRSpec IFU

The study of starburst- and AGN-driven feedback is fundamental for understanding the processes that shape galaxy growth, quench star formation, and drive the co-evolution of galaxies and their central black holes. We present a spatially resolved study of six galaxies at $3 < z < 9$, including starburst- and AGN-dominated systems, observed with JWST/NIRSpec IFU in low- ($R \sim 100$) and high-resolution ($R \sim 2700$) mode. Previous analysis of $R \sim 2700$ data revealed ionized outflows in all these galaxies. We explore possible links between outflows and stellar population properties to assess the mechanisms driving galaxy evolution at early epochs. Combining the spatially resolved stellar population analysis with the outflow properties, we find that the most massive galaxies ($M_\star > 5 \times 10^{10} M_\odot$) with strong AGN-driven ionized outflows show evidence of past quenching episodes occurring within the last $\sim 100$--$300$ Myr, mainly in the nuclear regions ($r < 3$ kpc). In contrast, higher-redshift ($z > 5$) and less massive ($M_\star < 10^{10} M_\odot$) starburst galaxies with powerful (starburst-driven) outflows appear to have experienced continuous growth, with no clear sign of quenching. Massive galaxies with weaker outflows do not show evidence of quenching in their history. One massive AGN host (GS20936) shows evidence for a recent ($10$--$30$ Myr) rejuvenation phase, likely fueled by a recent major merger. These results suggest that (AGN-driven) outflows can already play a key role in shaping the SFHs of massive galaxies at early cosmic epochs.

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Multiphase images of a powerful supernova-driven wind in the early Universe

Galactic winds are considered a likely driver of rapid quenching in early massive galaxies, but until now there has been no direct evidence that such systems drive winds powerful enough to meaningfully suppress their star-formation. We present resolved cold gas and ionized gas observations of a powerful supernova-driven wind in a massive galaxy 1.1 billion years after the Big Bang (at $z$=5.3). The outflow, likely triggered by ongoing merger activity, is removing gas at twice the rate of star-formation and could plausibly eject all the cold gas from the galaxy within 100 Myr. Our results suggest that powerful merger-driven outflows may be a key mechanism to produce abundant massive quiescent galaxies in the early Universe when a large fraction of massive galaxies are interacting. The mass and energetics of this distant outflow are consistent with nearby starburst-driven superwinds, suggesting that the efficiency of stellar feedback has remained relatively constant over the last 12 billion years of cosmic history.

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Little Red and Blue Dots: simply stratified Broad Line Regions

It has been claimed that a fraction of the so-called Little Red Dots (LRDs) are characterised by exponential broad line profiles, which have been ascribed to broadening from electron scattering by an ionised cocoon. In this work, we investigate the H$α$ broad line profiles of 32 AGN, including Little Red Dots (LRDs), Little Blue Dots (LBDs), and X-ray detected sources, using high SNR and resolution spectroscopy. We find that while single Gaussian models are statistically rejected, the exponential model is not universally preferred. Lorentzian and multi-Gaussian profiles provide equally good or superior fits for the majority of the sample, with no statistical preference for exponential profiles in $\sim$60% of cases across all AGN subtypes. There are indications that exponential profiles are preferred more frequently among LBDs, indicating that exponential profiles are not a prerogative of LRDs, which actually seem to more often favour Lorentzian profiles. Furthermore, we demonstrate that exponential wings can emerge naturally from the stratification of BLR clouds in virial motion, without invoking any scattering process. More generally, we also show that stacking multiple broad lines (either from multiple objects, as done in previous works, or from different BLR components within the same object) generally yields an exponential profile, even if none of the individual profiles are exponential. Explaining the exponential profiles in terms of BLR stratification solves various observational tensions with the electron scattering interpretation. While electron scattering may play a role, there is no evidence that it dominates the line profiles and that it significantly affects the inferred black hole masses.

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The Little Blue and Red Dots Rosetta Stones: Non-Gaussian broad lines, hot dust, and X-ray weakness

The population of Active Galactic Nuclei (AGN) newly discovered by the James Webb Space Telescope (JWST) exhibits peculiar properties that distinguish it from both local type I AGN and high-redshift quasars. Most of these sources are compact, appearing as 'little dots': among them, the sub-class (10-30% of the total) characterized by significantly red optical colors has been named 'Little Red Dots' (LRDs), while here we analogously introduce the term 'Little Blue Dots' (LBDs) for the remaining, bluer sources (70-90%). We then present a comparative analysis of the prototypical representatives ('Rosetta Stones') of the two classes: GN-28074 at z=2.26, the Red Rosetta Stone, and GS-3073 at z=5.55, the Blue Rosetta Stone. In both Rosetta Stones the broad Balmer lines are better described by exponential profiles rather than single Gaussians, similarly to normal low-redshift type I AGN, indicating that exponential profiles are not unique to LRDs. They are both extremely X-ray weak, show strong auroral [OIII] 4363 emission, weak hot dust mid-IR emission, and no time variability. However, they differ in terms of excitation diagnostics: the HeII 4686 line is undetected in the Red Rosetta but strongly detected in the Blue Rosetta in both narrow and broad components, with the latter much broader than hydrogen Balmer lines. This supports BLR stratification and disfavors the cocoon electron-scattering scenario. An additional difference is the presence of prominent Balmer absorption in the Red Rosetta -- indicative of extremely dense gas along the line of sight -- but absent in the Blue Rosetta. Taken together, these results suggest that LRDs and LBDs share the same central engine as standard type I AGN, while differing in the amount and geometry of dense gas surrounding the accretion disk, and/or in their accretion properties.

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There Is More to Outshining: 2D Dust Effects on Stellar Mass Estimates at $3 \leq z < 9$ with JWST in the JADES Field

Dust attenuation modifies the observed spectral energy distribution (SED), leading to biases in the properties inferred from integrated SED fitting. As spatially resolved SED modeling becomes feasible for large high-redshift samples, it is increasingly important to assess how dust attenuation affects resolved mass estimates. We evaluate the impact of dust attenuation on stellar mass estimates derived from integrating spatially resolved SED fitting results. We perform spatially resolved and integrated SED fitting on a sample of 3408 galaxies at $3 \leq z < 9$ from the GOODS South field, combining deep NIRCam from the JWST Advanced Deep Extragalactic Survey (JADES) and HST/ACS imaging from GOODS and CANDELS. We compare galaxy-integrated properties derived from fitting the summed SED with those obtained from spatially resolved SED modeling. Using a two-component dust attenuation model with a variable slope, we investigate how the dust attenuation slope, A(V), and stellar population properties contribute to discrepancies in the resulting stellar mass estimates. Resolved stellar masses are systematically higher than integrated estimates, with a median offset of +0.24 dex. Resolved analyses recover higher dust attenuations ($ΔA(V)\approx +0.08$ mag), lower birth cloud fractions ($Δμ\approx -0.28$), and grayer attenuation curves ($Δδ_{\mathrm{ISM}} = +0.08$), arising from preferential sampling of compact star-forming regions. Integrated fits underestimate stellar ages by $\sim23\%$ at $z < 5$ and 31$\%$ at $z \gtrsim 5$. The stellar mass offset correlates strongly with the age difference and the attenuation slope difference, indicating that age-dependent outshining and spatially varying dust geometry are primary drivers of the discrepancy between resolved and integrated stellar masses.

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RotCurves: A PYTHON package for efficient modelling and fitting of galactic rotation curves at high-z

Rotation curves are a fundamental tool in the study of galaxies across cosmic time, and with the advent of large integral field unit (IFU) kinematic surveys there is an increasing need for efficient and flexible modelling tools. We present RotCurves, a parametric forward-modeling tool designed for rotation curve analysis at high-z, correcting for ``beam smearing" by projecting and convolving the beam PSF in the plane of the galaxy. We benchmark RotCurves against the established parametric code dysmalpy using synthetic observations. The typical runtime with RotCurves is a few ~10ms, a factor 250 faster than dysmalpy for a single realization. For well-resolved systems (PSF FWHM < Reff), the mock observed rotation and dispersion curves agree to within 5% up to 3Reff, where most of the discrepancies are in the inner disk. whereas in marginally resolved systems (PSF FWHM > 1.5 Reff) discrepancies increase to up to 15%. Using a built-in MCMC fitting procedure, RotCurves recovers well the intrinsic model parameters across a wide range of galaxy properties and accounting for realistic noise patterns. Systematic biases emerge for the effective radius and for low disk masses (Mdisk < 3x10^9 Msun). We show excellent parameter recovery at high signal-to-noise ratios (S/N > 25), with increasing deviations in parameter recovery at lower S/N. RotCurves is best suited for inclinations of 10 < i < 80. RotCurves is built as an exploratory tool for rapid testing of mass model assumptions, parameter studies and for efficiently processing large samples of observational data from large IFU surveys. The code is publicly available on github.

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The ALPINE-CRISTAL-JWST Survey: JWST/IFU Optical Observations for 18 Main-Sequence Galaxies at z=4-6

To fully characterize the formation and evolution of galaxies, we need to observe their stars, gas, and dust on resolved spatial scales. We present the ALPINE-CRISTAL-JWST survey, which combines kpc-resolved imaging and spectroscopy from HST, JWST, and ALMA for 18 representative main-sequence galaxies at z=4-6 and log(M/$M_\odot$) > 9.5 to study their star formation, chemical properties, and extended gas reservoirs. The co-spatial measurements resolving the ionized gas, molecular gas, stars, and dust on 1-2 kpc scales make this a unique benchmark sample for the study of galaxy formation and evolution at $z\sim5$, connecting the Epoch of Reionization with the cosmic noon. In this paper, we outline the survey goals and sample selection, and present a summary of the available data for the 18 galaxies. In addition, we measure spatially integrated quantities (such as global gas metallicity), test different star formation rate indicators, and quantify the presence of H$α$ halos. Our targeted galaxies are relatively metal rich (10-70% solar), complementary to JWST samples at lower stellar mass, and there is broad agreement between different star formation indicators. One galaxy has the signature of an active galactic nuclei (AGN) based on its emission line ratios. Six show broad H$α$~emission suggesting type 1 AGN candidates. We conclude with an outlook on the exciting science that will be pursued with this unique sample in forthcoming papers.

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Spatially resolved broad line region in a quasar at z=4: Dynamical black hole mass and prominent outflow

We present the first near-infrared interferometric data of a QSO at z=4. The K-band observations were performed with GRAVITY+ on the VLTI using all four UTs, detecting a differential phase signal that traces the spatially resolved kinematics for both the \hb\ and \hg\ lines in the broad line region. We fit the two lines simultaneously with an updated model that includes distinct rotating and conical outflowing components. For the best fit model, more than 80\% of the \hi\ line emission from the BLR originates in an outflow with a velocity up to $10^4$ km s$^{-1}$. This is oriented so that our line of sight is along an edge of the conical structure, which produces the prominent blue wing on the line profile. A combination of anisotropic line emission and mid-plane opacity lead to the single-sided phase signal. The model is able to qualitatively match both the outflowing \civ\ line profile and the systemic \oi\ fluorescent emission. The derived black hole mass of $8\times10^8$ M$_\odot$ is the highest redshift black hole mass measurement to date obtained directly from BLR dynamics. It is an order of magnitude lower than that inferred from various single epoch scaling relations, and implies that the accretion is highly super-Eddington. With reference to recent simulations, the data suggest that this QSO is emitting close to its radiative limit in a regime where strong outflows are expected around a polar conical region.

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The radio properties of the JWST-discovered AGN

We explore the radio emission of JWST-selected Broad Line AGN (BLAGN, or type 1) in the GOODS-N field. We use deep radio data at different frequencies (144\,MHz, 1.5\,GHz, 3\,GHz, 5.5\,GHz, 10\,GHz), and we find that none of the {37} sources investigated is detected at any of the aforementioned frequencies. Similarly, the radio stacking analysis does not reveal any detection down to an rms of ${\sim 0.15}μ$Jy beam$^{-1}$, corresponding to a $3σ$ upper limit at rest frame 5 GHz of $L_{5GHz}=2\times10^{39}$ erg s$^{-1}$ at the mean redshift of the sample $z\sim 5.1$. We compared this and individual sources upper limits with expected radio luminosities estimated assuming different AGN scaling relations, {to check whether these are consistent with the standard BLAGN spectral energy distribution}. For most of the sources the radio luminosity upper limits are still compatible with expectations for radio-quiet (RQ) AGN; nevertheless, the more stringent stacking upper limits and the fact that no detection is found {might suggest} that JWST-selected BLAGN are weaker than standard AGN even at radio frequencies. Indeed, the probability of having none of the BLAGN detected in none of the investigated radio images is expected to be on average very low ($P<10^{-4}$). We discuss some scenarios that could explain the possible radio weakness, such as free-free absorption from a dense medium, or the lack of either magnetic field or a corona, possibly as a consequence of super-Eddington accretion. These scenarios would also explain the observed X-ray weakness. We also conclude that $\sim$1 dex more sensitive radio observations are needed to better constrain the level of radio emission (or lack thereof) for the bulk of these sources. The Square Kilometer Array Observatory (SKAO) will likely play a crucial role in assessing the properties of this AGN population.

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Tentative rotation in a galaxy at z$\sim$14 with ALMA

We re-analysed ALMA observations of the [OIII]$λ$88$μ$m emission line in JADES-GS-z14.0, so far the most distant spectroscopically confirmed galaxy at z=14.18. Our analysis shows a tentative detection of a velocity gradient of [OIII]$λ$88$μ$m using three independent tests: 1) construction of moment maps; 2) extraction of integrated spectra from a grid of apertures; and 3) spectro-astrometry in both the image and uv planes. We performed kinematical fitting using the KinMS code and estimated a dynamical mass of log$_{10}$(M$_{\rm dyn}$/$\rm M_\odot$)= 9.4$^{+0.8}_{-0.4}$, with the bulk of the uncertainties due to the degeneracy between dynamical mass and inclination. We measure an upper limit on the velocity dispersion ($σ_{v}$) of $<40~$ km/s~which results in an estimate of V$_{\rm rot}/σ>$ 2.5. This result, if confirmed with higher-resolution observations, would imply that kinematically cold discs are already in place at $z\sim14$. Comparison with mock observations from the SERRA cosmological simulations confirms that even low-resolution observations are capable of detecting a velocity gradient in $z>10$ galaxies as compact as JADES-GS-z14.0. This work shows that deeper ALMA or JWST/NIRSpec IFS observations with high spatial resolution will be able to estimate an accurate dynamical mass for JADES-GS-z14.0, providing an upper limit to the stellar mass of this over-luminous galaxy.

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JADES: Carbon-enhanced, Nitrogen-normal compact galaxy at z=11.2

Over the past few years \textit{JWST} has been a major workhorse in detecting and constraining the metal enrichment of the first galaxies in the early Universe and finding the source of the ionisation of their interstellar medium. In this work, we present new deep JWST/NIRSpec spectroscopy of GS-z11-1, a galaxy at z = 11.28, in which we report the detection of multiple rest-frame UV and optical emission lines: CIII]$λλ$1907,09, CIV]$λλ$1548,51, [OII]$λλ$3726,29, [NeIII]$λ$3869, H$γ$ and tentative evidence for HeII$λ$1640. The ionisation properties of GS-z11-1 are consistent with star formation, with potential contribution from an active galactic nucleus (AGN). We estimate a galaxy stellar mass of log(M$_{*}$/M$_{\odot}$) = 7.8$\pm$0.2 and log(SFR/(M$_{\odot}$ yr$^{-1}$))= 0.32$\pm$0.11 for the fiducial SF-only models. We measured C/O from the SED modelling of C/O = 1.20$\pm0.15 \times$ solar. This is one of the highest C/O abundances at z$>$10, and it is consistent with either PopII and PopIII enrichment paths. Despite this source being extremely compact, with a half-light radius of 73$\pm$10 pc, we see no increased equivalent width of NIV] and NIII] emission lines as seen in some other compact sources at similar redshifts, a potential signature of second-generation stars in GCs. Overall, this galaxy exhibits low metallicity and high ionisation parameter consistent with intense star-formation or AGN activity in the early Universe, possibly observed before the enrichment by the second generation of stars in proto-globular clusters in the core of the galaxy.

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Not Just a Dot: the complex UV morphology and underlying properties of Little Red Dots

We analyze 99 photometrically selected Little Red Dots (LRDs) at $z \approx 4-8$ in the GOODS fields, leveraging ultra-deep JADES NIRCam short-wavelength (SW) data. We examine the morphology of 30 LRDs, while the remaining 69 appear predominantly compact, with sizes $\leq 400$ pc and no extended components even in stacked SW images. However, their unresolved nature may partly reflect current depth limitations, which could prevent the detection of faint diffuse components. Among the 30 morphologically analyzed LRDs, 50% show multiple associated components, while the rest exhibit highly asymmetric structures, despite appearing as single sources. This diversity in rest-frame UV morphologies may point to interactions or strong internal feedback. We find median stellar masses of $\log_{10}(M_{\star}/M_{\odot}) = 9.07_{-0.08}^{+0.11}$ for pure stellar models with $A_{V} \approx 1.16^{+0.11}{-0.21}$ mag, and $\log{10}(M_{\star}/M_{\odot}) = 9.67^{+0.17}{-0.27}$ for models including AGNs with $A{V} \approx 2.74^{+0.55}_{-0.71}$ mag, in line with recent studies suggesting higher masses and dust content for AGN-fitted LRDs. NIRSpec spectra are available for 15 sources, six of which are also in the morphological sample. Broad H$α$ is detected in 40% (FWHM = 1200-2900 km/s), and one source shows broad H$β$ emission. Emission line ratios indicate a composite nature, consistent with both AGN and stellar processes. Altogether, these results suggest that LRDs are a mixed population, and their rest-frame UV morphology reflects this complexity. Morphological studies of larger samples could provide a new way to understand what drives their properties and evolution.

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JADES Data Release 4 -- Paper II: Data reduction, analysis and emission-line fluxes of the complete spectroscopic sample

We present the fourth data release of JADES, the JWST Advanced Deep Extragalactic Survey, providing deep spectroscopic observations in the two GOODS fields. A companion paper presents the target selection, spectroscopic redshifts and success rates, and in this paper, we discuss the data reduction and present emission line flux measurements. The spectroscopy in this work consists of medium-depth, deep and ultradeep NIRSpec/MSA spectra of 5,190 targets, covering the spectral range $0.6\text{--}5.5$~\mum and observed with both the low-dispersion prism ($R=30\text{--}300$) and all three medium-resolution gratings ($R=500\text{--}1,500$). We describe the data reduction, analysis and description of the data products included in this data release. In total, we measured 3,297 robust redshifts out of 5,190 targets, spanning a redshift range from $z=0.5$ up to $z=14.2$, including 974 at $z>4$. This data release includes 1-d and 2-d fully reduced spectra with 3 and 5 pixel extractions, with slit-loss corrections and background subtraction optimized for point sources. Furthermore, we provide redshifts and $S/N>5$ emission-line flux catalogues for the prism and grating spectra, as well as new guidelines to use these data products. Lastly, we are launching a new JADES Online Database, designed to enable quick selection and browsing of this data release. Altogether, these data provide the largest statistical sample to date to characterise the properties of galaxy populations across Cosmic time.

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GA-NIFS: Mapping $z\simeq3.5$ AGN-driven ionized outflows in the COSMOS field

Active galactic nuclei (AGNi) are a key ingredient in galaxy evolution and possibly shape galaxy growth through the generation of powerful outflows. Little is known regarding AGN-driven ionized outflows in moderate-luminosity AGNi (logLbol[erg/s]<47) beyond cosmic noon (z>3). We present the first systematic analysis of the ionized outflow properties of a sample of X-ray-selected AGNi (logLx[erg/s]>44) from the COSMOS-Legacy field at z~3.5 and with logLbol[erg/s]=45.2-46.7, by using JWST NIRSpec/IFU spectroscopic observations as part of the GA-NIFS program. We spectrally isolated and spatially resolved the ionized outflows, through a multi-component kinematic decomposition of the rest-frame optical emission lines. JWST/NIRSpec IFU data also revealed a wealth of close-by companions, of both non-AGN and AGN nature, and ionized gas streams likely tracing tidal structures and large-scale ionized gas nebulae, extending up to the circumgalactic medium. Ionized outflows are detected in all COS-AGNi targets, which we compared with results from the literature up to z~3, opportunely (re-)computed. We normalized outflow energetics ($\dot{M}_{out}$, $\dot{E}_{out}$) to the outflow density in order to standardize the various assumptions that were made in the literature. Our choice is equal to assuming that each outflow has the same gas density. We find GA-NIFS AGNi to show outflows consistent with literature results, within the large scatter shown by the collected measurements, thus suggesting no strong evolution with redshift in terms of total mass outflow rate, energy budget, and outflow velocity for fixed bolometric luminosity. Moreover, we find no clear redshift evolution of the ratio of mass outflow rate and kinetic power over AGN bolometric luminosity beyond z>1. In general, our results indicate no significant evolution of the physics driving outflows beyond z~3.[abridged]

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Evolution of Gas Velocity Dispersion in Discs from $z\sim8$ to $z\sim0.5$

Together optical/near infrared integral field spectroscopy and resolved sub-millimetre interferometry data have mapped the ionised and molecular gas motions in nearly one thousand galaxies at redshifts $z>0.5$. While these measurements have revealed a number of key properties about the evolution of disc structure and kinematics, heterogenous techniques and samples have led to disparate findings - especially when comparing different dynamical tracers (e.g., H$α$, [C$\scriptstyle\rm~II$], CO). In this paper we present a literature compilation of 237 disc galaxies with measurements of velocity dispersion and rotational velocity between $z=0.5-8$, a subset of 63 galaxies have measurements of molecular gas fractions. We explore the connection between disc velocity dispersion measurements over 8 Gyrs as traced by multiple phases with the expectations from Toomre stability models. When sample properties are taken into account (e.g., stellar mass, tracer) there is little evolution in disc dispersions between $z\sim1.5-8$, consistent with expectations from model assumptions. We find ionised gas dispersions are higher by $\sim2\times$ from molecular gas dispersions at a fixed gas mass. These results are sensitive to the molecular gas tracer with results from [C$\scriptstyle\rm~II$] showing mixed behaviour indicative of its multi-phase origin. The [C$\scriptstyle\rm~II$] kinematics can be reconciled with molecular and ionised gas tracers when star-formation rates are taken into account.

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The ALMA-CRISTAL survey: Gas, dust, and stars in star-forming galaxies when the Universe was ~1 Gyr old I. Survey overview and case studies

We present the ALMA-CRISTAL survey, an ALMA Cycle 8 Large Program designed to investigate the physical properties of star-forming galaxies at $4 \lesssim z \lesssim 6$ through spatially resolved, multi-wavelength observations. This survey targets 19 star-forming main-sequence galaxies selected from the ALPINE survey, using ALMA Band 7 observations to study [CII] 158 $μ$m line emission and dust continuum, complemented by JWST/NIRCam and HST imaging to map stellar and UV emission. The CRISTAL sample expanded to 39 after including newly detected galaxies in the CRISTAL fields, archival data, and pilot study targets. The resulting dataset provides a detailed view of gas, dust, and stellar structures on kiloparsec scales at the end of the era of reionization. The survey reveals diverse morphologies and kinematics, including rotating disks, merging systems, [CII] emission tails from potential interactions, and clumpy star formation. Notably, the [CII] emission in many cases extends beyond the stellar light seen in HST and JWST imaging. Scientific highlights include CRISTAL-10, exhibiting an extreme [CII] deficit similar to Arp 220; and CRISTAL-13, where feedback from young star-forming clumps likely causes an offset between the stellar clumps and the peaks of [CII] emission. CRISTAL galaxies exhibit global [CII]/FIR ratios that decrease with increasing FIR luminosity, similar to trends seen in local galaxies but shifted to higher luminosities, likely due to their higher molecular gas content. CRISTAL galaxies also span a previously unexplored range of global FIR surface brightness at high-redshift, showing that high-redshift galaxies can have elevated [CII]/FIR ratios. These elevated ratios are likely influenced by factors such as lower metallicity gas, the presence of significant extraplanar gas, and contributions from shock-excited gas.

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