arXiv subjects

G. Cresci

Publications and source records attributed to G. Cresci.

At least 19 recordsLinked to original sources

arXiv2026

Cosmic evolution of the helium and oxygen abundances in type 2 Active Galactic Nuclei: Helium-loud AGNs

We derive the helium and oxygen abundances in the Narrow Line Regions (NLRs) of 84 Active Galactic Nuclei (AGNs) spanning two redshift ranges: 65 objects at $z \: < \: 0.2$ and 19 objects at $2.8 \lesssim z \lesssim 6.8$. Spectroscopic data in the optical rest-frame range [3000 ${\lambda}(\text{\AA})$ 7000] from the JADES survey and from the literature were used to estimate $\text{He/H}$ and $\text{O/H}$ via the $T_{\rm e}$-method (7 objects) and strong-emission line calibrations (19 objects). Our results indicate that the ionization degree in AGNs increases toward higher redshifts, exhibiting a trend similar to that observed in star-forming galaxies. We find that the majority of our sample of AGNs at $z \: > \: 2.8$ show oversolar helium abundances and subsolar oxygen abundances. We identified, via the $T_{\rm e}$-method, an object (goods-s-mediumhst-58850; $z=6.2615$) with the highest helium abundance estimated to date, i.e. $12+\log({\rm He/H})=11.64$, corresponding to $\rm (He/He_{\odot}) \sim 4.4$. This result remains robust even when we adopt larger electron densities (varying $N_{\rm e}$ from $500$ to $10\:000$ $\rm cm^{-3}$) in abundance estimates using the $T_{\rm e}$-method and empirical strong-line methods. We found marginal evidence for a decline in the He/H abundance ($\sim 0.04$ dex per redshift unit) toward lower redshifts. In contrast, we found evidence for an increase in $\text{O/H}$ toward the local universe at a rate of approximately 0.06 dex per redshift unit.

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arXiv2026

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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arXiv2026

Supermassive Black Hole Winds in X-rays: SUBWAYS IV. Tracing Radio Emission and Unveiling the Role of Winds

Most Active Galactic Nuclei (AGN) are Radio Quiet, with radio emission that may arise from star-formation activity, AGN-driven winds, weak jets, and coronal activity. Disentangling these mechanisms is challenging and requires detailed multi-wavelength investigation, but it is crucial for quantifying AGN feedback in galaxy evolution. We present a detailed radio investigation of 21 X-ray selected AGN in the Supermassive Black Hole Winds in X-Rays (SUBWAYS) sample (log Lbol = 44.9-46.3 erg/s, z=0.1-0.5), selected to systematically search for Ultra-Fast Outflows (UFOs). UFOs are detected in 30% of the targets, making the sample particularly well-suited for investigating the role and signatures of multi-scale outflows at different frequencies. We build the radio SED of the sources complementing our proprietary data, collected with the JVLA at 1.5 and 6 GHz, with images from LoTSS and other publicly available radio surveys between 150 and 1400 MHz. We investigate the role and occurrence of the aforementioned mechanisms, with particular interest in outflows and their possible relation with UFOs. We combined information on spectral indices, luminosities, and morphologies of the radio emission with properties derived in other wavebands, such as Star Formation Rate, X-ray luminosity, Eddington ratio or the UFO kinetic luminosity. All the sources are detected and are mostly consistent with RQ AGN. For 80% of the sources the data suggest the presence of an outflow (wind or weak jet). Interestingly, our results indicate that AGN with UFOs tend to have larger radio extension and a steep radio spectrum consistent with outflows. Moreover, the radio emission of the 6 UFO hosts is consistent with predictions from wind-driven shock models, possibly indicating a direct connection between the two phases. Alternatively, this may reflect physical conditions favouring the rise of both phenomena.

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arXiv2026

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$\alpha$ 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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arXiv2026

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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arXiv2026

Fast, dust-poor outflows in the local candidate dual AGN MCG-03-34-64 observed with VLT/ERIS

We present VLT/ERIS IFU J-band observations of MCG-03-34-64, a nearby (z = 0.0167) Seyfert galaxy hosting a candidate dual AGN system with a separation of ~100 pc between the nuclei. The observations cover, among others, the HeI1.083um, [FeII]1.257um and Pa$\beta$ emission lines, over a FoV of 3"x3"(~1x1 kpc$^2$). We analyse the ionised gas kinematics and identify two regions with enhanced velocity dispersion (W80~1500 km/s), suggestive of fast outflowing gas, spatially coincident with the position of the two candidate active nuclei. The spectra of the two outflows show a prominent blueshifted wing with velocities vmax ~ -1700 km/s corresponding to the highest 2-5 percentiles of samples of local AGN with similar bolometric luminosities. For the ionised phase of the two outflows, we derive comparable masses of $(4\pm1)\times 10^5$ $M_{\odot}$ and mass outflow rates of $20\pm5$ $M_{\odot}$/yr. The two distinct outflows could be associated with the two nuclei, or be generated by the interaction of the radio jet with the ISM. We also analyse the peculiar profile of the [Fe VII]6087A optical coronal line from an archival VLT/X-shooter spectrum. The comparison with the [NeV]3425A and [FeII]1.257um profiles indicates that [Fe VII] emission likely arises only from the outflow. The absence of the systemic component in [Fe VII] - unlike in [NeV], which has similar ionisation potential and critical density - suggests suppression of [Fe VII] due to iron depletion onto dust grains, while its detection in the outflow implies a lower dust content than in the host ISM. The additional information gained from the ERIS data are consistent with the scenario of a dual AGN, however further observations are required to confirm its nature.

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arXiv2026

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$\alpha$ 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}$$\sim0.59$ mag on average) and metal-enriched (0.13 dex) than the interstellar medium (ISM) of the host galaxies, but its velocities are insufficient to escape the galaxies and reach the circumgalactic medium, suggesting that outflows mainly redistribute dust and metals around their hosts. The outflows identified in this study display velocity dispersions within $\sigma_{\rm out}=130-340$~km~s$^{-1}$ and outflow velocities $v_{\rm out}=170-600$~km~s$^{-1}$, and, when combined with less luminous and less massive star-forming galaxies from previous works, reveal a statistically significant correlation between $v_{\rm out}$ and star formation rate (SFR). The typically low mass-loading factors ($\eta=\dot{M}_{\rm out}/SFR$$\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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arXiv2025

Cosmic Duets I. High-spatial resolution spectroscopy of dual and lensed AGN with MUSE-NFM

We present the first-year results of the MUSE Large Program "Cosmic Duets", whose goal is to obtain adaptive-optics assisted MUSE observations with an angular resolution of 0.1"-0.2" in order to provide integral-field spectroscopy of sub-arcsec separation dual and lensed active galactic nucleus (AGN) candidates. These observations reveal previously unexplored properties of dual and lensed systems that are key to understanding galaxy evolution, supermassive black hole mergers, and strong-lensing modeling. Targets were efficiently selected using the Gaia multipeak (GMP) technique, which identifies pairs of point-like sources with separations below 0.8" in the Gaia catalog. MUSE spatially resolved spectroscopy provides accurate redshifts, ionization diagnostics, and identification of absorption systems along the line of sight. We report results for 30 GMP targets at z=0.5-3.5. All systems show at least 2 spatially resolved components. 19 objects are confirmed as AGN multiplets, including 6 dual AGN, 10 doubly lensed quasars, and 3 quadruply lensed systems, while the remaining 11 correspond to chance alignments with foreground stars. Among all the spectroscopically confirmed dual AGN in the literature, 27 pairs have projected separations below 7kpc in this redshift regime, and our sample accounts for 22% of the total. We studied dual and lensed AGN distributions as a function of redshift, magnitude, and projected separation while accounting for selection effects, and we find that bright systems are dominated by lensed quasars, whereas the relative fraction of dual AGN increases at fainter magnitudes. This first-year sample demonstrates the high efficiency of GMP selection combined with MUSE spectroscopy for identifying sub-arcsec dual and lensed AGN. The full program, targeting 150 systems, will enable statistical studies of dual AGN and constraints on mass distribution in lensing galaxies.

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arXiv2025

MIRACLE III. JWST/MIRI expose the hidden role of the AGN outflow in NGC 1068

We present new JWST IFS observations of the active galaxy NGC 1068, combining Mid-IR and optical IFS data from MIRI and MUSE to characterize the multi-phase circumnuclear gas properties and its interaction with the AGN outflow and radio jet. MIRI data trace the multiphase gas emission up to 400 pc from the nucleus at 20--60 pc resolution, unveiling a clumpy ionized structure around the radio hot-spots and a rotating warm molecular disc. Innovative Mid-IR diagnostic diagrams highlight the role of the AGN as the main excitation source for the ionized gas in the entire MIRI field of view, consistent with optical diagnostics, and supporting the AGN-driven wind scenario. Density sensitive [NeV] and [ArV] Mid-IR transitions reveal high-density clumps (n_e > 10**4 cm**-3) along the edges of the jet and outflow, tracing gas compression by the expanding wind. We combined multi-cloud kinematic (MOKA) and photo-ionization (HOMERUN) modeling to characterize the ionized outflow properties and found that [OIV] traces an outflow 300 km/s faster than that inferred from [OIII], showing that the two lines originate from distinct gas components. This kinematic dichotomy is confirmed by the photoionization analysis, which requires a dust-poor component dominating the optical lines and a dust-rich component responsible for the Mid-IR emission. The Mid-IR-revealed dusty component carries a significantly larger ionized-gas mass than what can be inferred from optical lines alone, showing that most of the outflowing mass is hidden from classical optical diagnostics. Our modelling point to a two-stage acceleration scenario, with velocities up to ~2000 km/s, consistent with an energy-driven wind. Our findings indicates that the outflow entrains up to a few 10**6 solar masses of ionized gas and couples efficiently with the surrounding ISM, injecting turbulence and impacting the host-galaxy environment.

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arXiv2025

Tracing nitrogen enrichment across cosmic time with JWST

We present a comprehensive analysis of the nitrogen-to-oxygen (N/O) abundance ratio in a sample of ~ 660 star-forming galaxies at redshift z ~ 1-6, with a median redshift of z = 3.0, using deep JWST/NIRSpec spectroscopy. Leveraging detections of faint auroral emission lines in 92 galaxies at z>1 from both the MARTA survey and a large compilation of high-redshift literature objects, we derive direct electron temperature-based abundances for nitrogen and oxygen using rest-frame optical lines. We establish the first high-redshift calibrations of strong-line N/O diagnostics based on 'direct' abundance measurements, finding a mild evolution for the N2O2 = log([NII]6585/[OII]3727,3729) diagnostic and no clear evolution for the N2S2 = log([NII]6585/[SII]6717,6731) diagnostic compared to local realisations. We then investigate the N/O-O/H relation across cosmic time using both 'direct' abundances and strong-lines based measurements (additional 535 galaxies). We find evidence for mild but systematic nitrogen enhancement at high redshift: galaxies at z>1 exhibit N/O ratios elevated by ~0.18 dex (median offset) at fixed O/H compared to local trends, with a more pronounced enhancement at low metallicity (i.e. 12 + log(O/H) < 8.1), where the offset reaches up to ~0.4-0.5 dex. We consider several scenarios to explain the observed trends, including bursty star formation, differential metal loading, and inflows of pristine gas. Our results provide the most extensive confirmation of elevated N/O ratios at high-redshift to date based on rest-optical diagnostics and within a self-consistent frame.

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arXiv2025

Connecting outflows with radio emission in active galactic nuclei at cosmic noon

AGN feedback is a well known mechanism in the evolution of galaxies. One open question is the driving mechanism of galaxy-scale outflows. At low redshift, radio jets often interact with the ISM, generating turbulence and driving ionized outflows. Despite this evidence at low redshift, relatively few studies have investigated the radio-ionized gas connection at cosmic noon. Thus, our main goal is to conduct a pilot study using VLA data for three quasars with moderate/high radio power, which have ionized outflows identified in observations from the SUPER survey. We used [OIII] data from SINFONI analyzed in earlier studies, along with new 6.2 GHz VLA radio observations, at comparable spatial resolution. We also incorporate radio data from the literature to explore the radio emission. We detected extended radio structure in our VLA A-array data for two quasars. The extended structure in J1333+1649 aligns with the smaller-scale emission seen in archival images, suggesting a jet propagating from nuclear to galaxy-wide scales. In all three quasars, we found that the brightest radio emission and ionized gas have comparable spatial scales. Furthermore, the position angles of the radio emission and ionized gas present small offsets for the two targets with extended structures. Given that the kinematics of the ionized gas in all three quasars is dominated by outflows, our results suggest a strong connection between radio emission and ionized outflows in typical AGN at cosmic noon. Based on energetic considerations and comparisons with archival data, radio jets could be a significant mechanism for driving outflows in AGN from cosmic noon to low redshifts. However, with the exception of one object (J1333+1649), we cannot rule out the possibility that the radio emission arises from shocks in the interstellar medium caused by disk winds or radiatively driven outflows.

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arXiv2025

The gas streamer G1-2-3 in the Galactic Center

The black hole in the Galactic Center, Sgr A*, is prototypical for ultra-low-fed galactic nuclei. The discovery of a hand-full of gas clumps in the realm of a few Earth masses in its immediate vicinity provides a gas reservoir sufficient to power Sgr A*. In particular, the gas cloud G2 is of interest due to its extreme orbit, on which it passed at a pericenter distance of around 100 AU and notably lost kinetic energy during the fly-by due to the interaction with the black hole accretion flow. 13 years prior to G2, a resembling gas cloud called G1, passed Sgr A* on a similar orbit. The origin of G2 remained a topic of discussion, with models including a central (stellar) source still proposed as alternatives to pure gaseous clouds. Here, we report the orbit of a third gas clump moving again along (almost) the same orbital trace. Since the probability of finding three stars on close orbits is very small, this strongly argues against stellar-based source models. Instead, we show that the gas streamer G1-2-3 plausibly originates from the stellar wind of the massive binary star IRS16SW. This claim is substantiated by the fact that the small differences between the three orbits - the orientations of the orbital ellipses in their common plane as a function of time - are consistent with the orbital motion of IRS 16SW.

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arXiv2025

Shocked, Heated, and Now Resolved: H$_2$ excitation in the low-luminosity AGN at M58 core with JWST

We present JWST NIRSpec and MIRI MRS observations of the central kiloparsec of M58 (NGC 4579), a nearby LINER galaxy hosting a low-luminosity AGN (LLAGN; $L_\mathrm{bol} \sim 10^{42}$ erg s$^{-1}$) with a low-power jet. These data provide an unprecedented view of the warm molecular gas phase and reveal clear signatures of feedback. We detect 44 H$_2$ lines, including bright pure rotational lines (S(1)-S(18)) and rovibrational lines up to $\nu=2$, probing a wide range of excitation conditions. Excitation diagrams show that rotational lines follow a power-law temperature distribution with an exponential cutoff, consistent with heating by low-velocity shocks. H$_2$ rovibrational lines deviate from thermal models primarily because of sub-thermal excitation at low density. Additionally, there may be a 10% contribution powered by AGN X-ray photons in the nucleus. The dust lanes associated with the spiral inflow appear dynamically undisturbed but show signs of shock heating, while the inner $\sim$200 pc exhibits turbulent kinematics produced by outflowing molecular gas. These results reveal the subtle yet measurable impact of LLAGN feedback on the interstellar medium, demonstrating that even weak, vertically oriented jets and low radiative accretion rates can perturb molecular gas and regulate nuclear reservoirs. This study highlights JWST's transformative ability to uncover hidden modes of AGN feedback.

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arXiv2025

M^3D: Mosaicking M33 with MUSE datacubes I. Unveiling the diversity of HII regions in M33 with MUSE

We present new VLT/MUSE observations of a 3 $\times$ 8 arcmin$^2$ mosaic along the southern major axis of the Local Group galaxy M33. These data provide an unprecedented view of the galaxy's interstellar medium (ISM) and allow us to resolve ionised nebulae at a spatial scale of $\approx$5 pc. We identified and catalogued 131 HII regions, down to H\alpha luminosities of $\approx 5\times$10$^{35}$ erg s$^{-1}$, one order of magnitude fainter than previous surveys on nearby galaxies beyond the Local Group, and we compared these regions with the spatial distribution of ionising stars and embedded star clusters. For each region, we extracted the corresponding integrated optical spectra and measured the intensity of key optical emission lines (H\beta, [OIII], [NII], H\alpha, [SII], [SIII]), other weaker optical lines when detectable, and Paschen lines to characterise the physical properties of the ioinised gas, such as density, dust attenuation, and metallicity. Our spatially resolved line ratio and flux maps reveal a remarkable diversity in ionisation properties, from dust-obscured regions hosting young stellar objects to highly ionised bubbles exhibiting high [OIII]/H\beta ratios. Our data reveal a diversity of ionisation fronts, ranging from well-defined to partial to absent. The radial profiles we obtained indicate the presence of both optically thin (density-bounded) HII regions permitting the escape of ionising photons and fully ionised, optically thick (ionisation-bounded) HII regions. The richness of this MUSE mosaic offers an unprecedented view of the ionised ISM at $\approx$5 pc resolution, providing direct insight into how stellar feedback shapes its environment.

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arXiv2025

The WISSH quasar project. XII. X-ray view of the most luminous quasi-stellar objects at Cosmic Noon

To improve our knowledge of nuclear emission in luminous QSOs at Cosmic Noon, we studied the X-ray emission of the WISE/SDSS-selected hyper-luminous (WISSH) QSO sample: 85 broad-line AGN with $L_{bol}>few\times 10^{47}\,erg\,s^{-1}$ at $z\sim 2-4$. Our aim is to characterise their X-ray spectra and explore relations between X-ray luminosity and other bands, comparing powerful QSOs with the general AGN population. We performed spectral analysis for about half of the sample; 16 sources were analysed via their hardness ratio; for the others we estimated their intrinsic luminosity $L_{2-10\,keV}$. Only 8 sources are undetected. We report a large dispersion in $L_{2-10\,keV}$ despite the narrow distribution of $L_{bol}$, $L_{2500\,\r{A}}$ and $\lambda L_{6\,\mu m}$ (about one-third of the sources classified as X-ray weak). This suggests differences in X-ray corona and accretion flow physics between hyper-luminous and less powerful AGN. X-ray photon index distribution is consistent with that of lower-$z$, lower-$L_{bol}$ AGN, and does not depend on the Eddington ratio ($\lambda_{Edd}$) or X-ray weakness. Most WISSH QSOs with intrinsic absorption estimates show little to no obscuration ($N_H \le 5\times 10^{22}\,cm^{-2}$). Among the obscured sources we find blue QSOs without broad absorption lines within the "forbidden region" of the $Log(N_H)-Log(\lambda_{Edd})$ plane, typically occupied by dust-reddened QSOs and associated with intense feedback. We confirm a correlation between $L_{2-10\,keV}$ and CIV line blueshift, a tracer of nuclear ionized outflows. Multi-wavelength data and complete X-ray coverage enabled the investigation of the disk-corona interplay at the highest luminosity regimes. The broad distribution of bolometric correction and X-ray - to - optical index suggest caution when using $L_{bol}$, $L_{2500\,\r{A}}$ or $L_{6\,\mu m}$ as direct X-ray proxy for individual luminous QSOs.

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arXiv2025

Euclid: A machine-learning search for dual and lensed AGN at sub-arcsec separations

Cosmological models of hierarchical structure formation predict the existence of a widespread population of dual accreting supermassive black holes (SMBHs) on kpc-scale separations, corresponding to projected distances < 0".8 at redshifts higher than 0.5. However, close companions to known active galactic nuclei (AGN) or quasars (QSOs) can also be multiple images of the object itself, strongly lensed by a foreground galaxy, as well as foreground stars in a chance superposition. Thanks to its large sky coverage, sensitivity, and high spatial resolution, Euclid offers a unique opportunity to obtain a large, homogeneous sample of dual/lensed AGN candidates with sub-arcsec projected separations. Here we present a machine learning approach, in particular a Convolutional Neural Network (CNN), to identify close companions to known QSOs down to separations of $\sim\,$0".15 comparable to the Euclid VIS point spread function (PSF). We studied the effectiveness of the CNN in identifying dual AGN and demonstrated that it outperforms traditional techniques. Applying our CNN to a sample of $\sim\,$6000 QSOs from the Q1 Euclid data release, we find a fraction of about 0.25% dual AGN candidates with separation $\sim\,$0".4 (corresponding to $\sim$3 kpc at z=1). Estimating the foreground contamination from stellar objects, we find that most of the pair candidates with separation higher than 0".5 are likely contaminants, while below this limit, contamination is expected to be less than 20%. For objects at higher separation (>0".5, i.e. 4 kpc at z=1), we performed PSF subtraction and used colour-colour diagrams to constrain their nature. We present a first set of dual/lensed AGN candidates detected in the Q1 Euclid data, providing a starting point for the analysis of future data releases.

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arXiv2025

MIRACLE II: Unveiling the multi-phase gas interplay in the circumnuclear region of NGC 1365 via multi-cloud modeling

We present a multi-phase study of the gas in the circumnuclear region (~1.1x1.0 kpc^2) of the nearby Seyfert 1.8 galaxy NGC 1365, observed in the context of the Mid-IR Activity of Circumnuclear Line Emission (MIRACLE) program. We combined spatially resolved spectroscopic observations from JWST/MIRI, VLT/MUSE, and ALMA to investigate the ionized atomic gas and the warm and cold molecular phases. MIRI data revealed over 40 mid-IR emission lines from ionized and warm molecular gas. Moment maps show that both cold and warm molecular gas follow the rotation of the stellar disk along the circumnuclear ring. The ionized gas displays flux and kinematic patterns that depend on ionization potential (IP): low-IP species (<25 eV) trace the disk, while higher-IP lines (up to ~120 eV) trace outflowing material. The [O III]5700 and [Ne V]14 lines both trace the southeast nuclear outflow cone. Additionally, [Ne V]14 detects the northwest counter-cone, obscured in the optical and thus invisible in [O III]5700. Mid-IR diagnostics, unlike optical ones, clearly reveal the AGN as the primary ionization source in the nucleus. Emission from high-IP species is spatially coincident with the ionization cones and not with star-forming regions. Using the [Ne V]24/[Ne V]14 ratio, we derive an electron density of (750+-440) cm^(-3), in agreement with values from the [S II] optical doublet. For the first time, we apply a fully self-consistent approach combining advanced photoionization and kinematic models (HOMERUN+MOKA3D) to constrain intrinsic outflow properties, overcoming the limitations of simplified classical methods. Exploiting the synergy of JWST/MIRI and VLT/MUSE, HOMERUN reproduces fluxes of over 60 emission lines from optical to mid-IR, disentangling AGN and star formation contributions and yielding robust estimates of outflow mass, geometry, and energetics.

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arXiv2025

JWST MIRI/MRS observations of hot molecular gas in an AGN host galaxy at Cosmic Noon

Active Galactic Nuclei (AGN) are believed to play a central role in quenching star formation by removing or destroying molecular gas from host galaxies via radiation-pressure driven outflows and/or radio jets. Some studies of cold molecular gas in galaxies at Cosmic Noon ($z\sim2$) show that AGN have less cold gas ($<$100 K) compared to mass-matched star-forming galaxies. However, cold gas could also be shock-heated to warmer phases, detectable via H$_{2}$ transitions in the rest-frame near- and mid-infrared spectra. The Medium Resolution Spectrograph (MRS) of the Mid-infrared Instrument (MIRI) aboard JWST has opened a unique window to observe these emission lines in galaxies at Cosmic Noon. We present the first detection of hot molecular gas in cid_346, an X-ray AGN at $z\sim2.2$, via the H$_{2}$ ro-vibrational transition at 2.12 $\mu$m. We measure a hot molecular gas mass of $\sim 8.0 \times 10^{5}$ M$_{\odot}$, which is $\sim 10^{5}-10^{6}$ times lower than the cold molecular gas mass. cid_346 is located in an environment with extended gas structures and satellite galaxies. This is supported by detection of hot and cold molecular gas out to distances $>$10 kpc in MIRI/MRS and ALMA data, respectively and ancillary NIRCam imaging that reveals two satellite galaxies at distances of $\sim$0.4 arcsec (3.3 kpc) and $\sim$0.9 arcsec (7.4 kpc) from the AGN. Our results tentatively indicate that while the CO(3-2)-based cold gas phase dominates the molecular gas mass at Cosmic Noon, H$_{2}$ ro-vibrational transitions are effective in tracing hot molecular gas locally in regions that may lack CO emission.

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