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Cosmic Duets I. High-spatial resolution spectroscopy of dual and lensed AGN with MUSE
Authors:
M. Scialpi,
F. Mannucci,
Q. D'Amato,
C. Marconcini,
G. Cresci,
A. Marconi,
L. Ulivi,
M. Fumagalli,
P. Rosati,
G. Tozzi,
M. V. Zanchettin,
E. Cataldi,
L. Battistini,
E. Bertola,
C. Bracci,
S. Carniani,
M. Ceci,
A. Chakraborty,
C. Cicone,
A. Ciurlo,
A. De Rosa,
G. Di Rosa,
A. Feltre,
M. Ginolfi,
I. Lamperti
, et al. (12 additional authors not shown)
Abstract:
We present the first-year results of the MUSE Large Program "Cosmic Duets", aimed at obtaining adaptive-optics assisted MUSE observations with an angular resolution of 0.1"-0.2", providing integral-field spectroscopy of sub-arcsec separation dual and lensed active galactic nuclei (AGN) candidates. These observations reveal previously unexplored properties of dual and lensed systems, key to underst…
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We present the first-year results of the MUSE Large Program "Cosmic Duets", aimed at obtaining adaptive-optics assisted MUSE observations with an angular resolution of 0.1"-0.2", providing integral-field spectroscopy of sub-arcsec separation dual and lensed active galactic nuclei (AGN) candidates. These observations reveal previously unexplored properties of dual and lensed systems, key to understanding galaxy evolution, black hole mergers, and strong-lensing modeling. Targets were selected using the Gaia Multi-Peak (GMP) technique, which identifies pairs of point-like sources with separations below 0.8" in the Gaia catalog. MUSE spatially resolved spectroscopy provides redshifts, ionization diagnostics, and absorption systems along the line of sight. We report results for 30 GMP-selected targets at z=0.5-3.5. All systems show at least two spatially resolved components. Nineteen 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 alignments with foreground stars. Among spectroscopically confirmed dual AGN in the literature, 24 pairs have separations below 7 kpc, and our sample accounts for 25% of them. We study dual and lensed AGN distributions as a function of redshift, magnitude, and projected separation, and find that bright systems (J<16.5) are dominated by lensed quasars, whereas the fraction of dual AGN increases at fainter magnitudes. This first-year sample demonstrates the high efficiency of GMP pre-selection combined with MUSE spectroscopy. The full program, targeting 150 systems, will enable statistical studies of dual AGN incidence and detailed constraints on mass distribution in strong-lensing galaxies.
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Submitted 12 December, 2025;
originally announced December 2025.
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MIRACLE III. JWST/MIRI expose the hidden role of the AGN outflow in NGC 1068
Authors:
C. Marconcini,
A. Marconi,
M. Ceci,
A. Feltre,
M. Tartenas,
K. Zubovas,
I. Lamperti,
G. Cresci,
L. Ulivi,
F. Mannucci,
E. Bertola,
C. Bracci,
E. Cataldi,
Q. D'Amato,
J. A. Fernandez-Ontiveros,
J. Fritz,
E. Hatziminaoglou,
I. E. Lopez,
M. Ginolfi,
C. Gruppioni,
M. Mingozzi,
B. Moreschini,
G. Sabatini,
F. Salvestrini,
M. Scialpi
, et al. (5 additional authors not shown)
Abstract:
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-s…
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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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Submitted 11 December, 2025;
originally announced December 2025.
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Tracing Nitrogen Enrichment across Cosmic Time with JWST
Authors:
E. Cataldi,
F. Belfiore,
M. Curti,
B. Moreschini,
A. Marconi,
R. Maiolino,
A. Feltre,
M. Ginolfi,
F. Mannucci,
G. Cresci,
X. Ji,
A. Amiri,
M. Arnaboldi,
E. Bertola,
C. Bracci,
M. Ceci,
A. Chakraborty,
F. Cullen,
Q. D'Amato,
C. Kobayashi,
I. Lamperti,
C. Marconcini,
M. Scialpi,
L. Ulivi,
M. V. Zanchettin
Abstract:
We present a comprehensive analysis of the nitrogen-to-oxygen (N/O) abundance ratio in star-forming galaxies at redshift z~1-6, with a median redshift of z=2.7, using deep JWST/NIRSpec spectroscopy. Leveraging detections of faint auroral emission lines in 76 galaxies at z>1 from both the MARTA survey and a large compilation of high-redshift literature objects, we derive direct electron temperature…
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We present a comprehensive analysis of the nitrogen-to-oxygen (N/O) abundance ratio in star-forming galaxies at redshift z~1-6, with a median redshift of z=2.7, using deep JWST/NIRSpec spectroscopy. Leveraging detections of faint auroral emission lines in 76 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 no significant evolution for either N2O2 = [NII]6585/[OII]3727,3729 and N2S2 = [NII]6585/[SII]6717,6731 diagnostics compared to local realisations. We then investigate the N/O-O/H relation across cosmic time using both direct abundances and strong-line based measurements (additional 430 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 the local relation, with a more pronounced enhancement at low metallicity (12+log(O/H) < 8.1) where the offset reaches up to ~0.3-0.4 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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Submitted 10 December, 2025; v1 submitted 8 December, 2025;
originally announced December 2025.
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M&M33: MUSE and M33 I. Unveiling the Diversity of HII Regions in M33 with MUSE
Authors:
A. Feltre,
F. Belfiore,
G. Cresci,
E. Corbelli,
N. Tomičić,
F. Mannucci,
A. Marconi,
E. Bertola,
C. Bracci,
M. Ceci,
M. Curti,
Q. D'Amato,
M. Ginolfi,
E. Koch,
I. Lamperti,
L. Magrini,
C. Marconcini,
A. Plat,
M. Scialpi,
G. Tozzi,
L. Ulivi,
G. Venturi,
M. V. Zanchettin,
A. Chakraborty,
A. Amiri
Abstract:
We present new VLT/MUSE mosaic observations of a 3 $\times$ 8 arcmin$^2$ area along the southern major axis of the nearby galaxy M33 at a distance of 840 kpc from the Milky Way. These data provide an unprecedented view of the galaxy interstellar medium (ISM), and allow us to resolve ionised nebulae at a spatial scale of $\approx$5 pc. We identify and catalogue 124 HII regions, down to H$α$ luminos…
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We present new VLT/MUSE mosaic observations of a 3 $\times$ 8 arcmin$^2$ area along the southern major axis of the nearby galaxy M33 at a distance of 840 kpc from the Milky Way. These data provide an unprecedented view of the galaxy interstellar medium (ISM), and allow us to resolve ionised nebulae at a spatial scale of $\approx$5 pc. We identify and catalogue 124 HII regions, down to H$α$ luminosities of $\approx 5\times$10$^{35}$ erg s$^{-1}$, one order of magnitude fainter than previous surveys on local galaxies, and compare these regions with the spatial distribution of ionising stars and embedded star clusters. For each region, we extract the corresponding integrated optical spectra and measured the intensity of key optical emission lines (H$β$, [OIII], [NII], H$α$, [SII], [SIII], other weaker optical lines when detectable, and Paschen lines) to characterize their physical properties of the ioinized gas such as density, dust attenuation, and metallicity. Our spatially resolved line ratio and flux maps reveal remarkable diversity in ionisation properties, from dust-obscured regions hosting young stellar objects to highly ionised bubbles exhibiting high [OIII]/H$β$ ratios (>5). Our data reveal a diversity of ionisation fronts, ranging from well-defined to partial to absent. Radial profiles indicate the presence of both optically thin (density-bounded) and optically thick (radiation-bounded) HII regions. Our study highlights the richness of this MUSE mosaic and their unparalleled view of the ISM. In particular, the ability to probe the ISM at $\approx$ 5 pc resolution opens a new window onto the complex structure of the ionised gas, enabling direct insight into how stellar feedback operates on the scales where it originates.
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Submitted 18 September, 2025;
originally announced September 2025.
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Euclid: A machine-learning search for dual and lensed AGN at sub-arcsec separations
Authors:
L. Ulivi,
F. Mannucci,
M. Scialpi,
C. Marconcini,
G. Cresci,
A. Marconi,
A. Feltre,
M. Ginolfi,
F. Ricci,
D. Sluse,
F. Belfiore,
E. Bertola,
C. Bracci,
E. Cataldi,
M. Ceci,
Q. D'Amato,
I. Lamperti,
R. B. Metcalf,
B. Moreschini,
M. Perna,
G. Tozzi,
G. Venturi,
M. V. Zanchettin,
Y. Fu,
M. Huertas-Company
, et al. (167 additional authors not shown)
Abstract:
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 len…
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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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Submitted 23 September, 2025; v1 submitted 26 August, 2025;
originally announced August 2025.
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MIRACLE II: Unveiling the multi-phase gas interplay in the circumnuclear region of NGC 1365 via multi-cloud modeling
Authors:
M. Ceci,
C. Marconcini,
A. Marconi,
A. Feltre,
I. Lamperti,
F. Belfiore,
E. Bertola,
C. Bracci,
S. Carniani,
E. Cataldi,
G. Cresci,
Q. D'Amato,
J. Fritz,
M. Ginolfi,
E. Hatziminaoglou,
M. Hirschmann,
M. Mingozzi,
B. Moreschini,
F. Mannucci,
G. Sabatini,
F. Salvestrini,
M. Scialpi,
G. Tozzi,
L. Ulivi,
G. Venturi
, et al. (3 additional authors not shown)
Abstract:
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.…
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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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Submitted 20 September, 2025; v1 submitted 10 July, 2025;
originally announced July 2025.
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MARTA: Temperature-temperature relationships and strong-line metallicity calibrations from multiple auroral-line detections at cosmic noon
Authors:
E. Cataldi,
F. Belfiore,
M. Curti,
B. Moreschini,
F. Mannucci,
Q. D'Amato,
G. Cresci,
A. Feltre,
M. Ginolfi,
A. Marconi,
A. Amiri,
M. Arnaboldi,
E. Bertola,
C. Bracci,
S. Carniani,
M. Ceci,
A. Chakraborty,
M. Cirasuolo,
F. Cullen,
C. Kobayashi,
N. Kumari,
R. Maiolino,
C. Marconcini,
M. Scialpi,
L. Ulivi
Abstract:
We present the first results from MARTA (Measuring Abundances at high Redshift with the T$_e$ Approach), a programme leveraging ultra-deep, medium-resolution JWST/NIRSpec spectroscopy to probe the interstellar medium (ISM) of star-forming galaxies at $z \sim 2 - 3$. We report detections of one or more auroral lines, including [O III]$\lambda4363$, [O II]$λ\lambda7320,7330$, [S II] $\lambda4068$, a…
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We present the first results from MARTA (Measuring Abundances at high Redshift with the T$_e$ Approach), a programme leveraging ultra-deep, medium-resolution JWST/NIRSpec spectroscopy to probe the interstellar medium (ISM) of star-forming galaxies at $z \sim 2 - 3$. We report detections of one or more auroral lines, including [O III]$\lambda4363$, [O II]$λ\lambda7320,7330$, [S II] $\lambda4068$, and [S III] $\lambda6312$ for 16 galaxies in the sample, providing measurements of multiple ionic temperatures. We tested the validity of the T[O II]-T[O III] relation at high redshift considering a total sample of 21 objects including literature data, and obtained a shallower slope than in the low-$z$ literature. However, such a slope is consistent with low-redshift data when ultra-low metallicity objects are considered. We assessed the correlation of the T[O II]-T[O III] relationship and its scatter on different physical parameters, finding a mild correlation with the ionisation parameter and radiation field hardness, while no significant correlation with gas density. The location of high-redshift data is also consistent with the low-$z$ literature in the T[O II]-T[S II], and T[S III]-T[O III] relations, although this conclusion is limited with low-number statistics. Finally, we leveraged our sample together with a comprehensive compilation of galaxies with [O III]$\lambda4363$ detections from the literature to recalibrate classical strong-line diagnostics at high redshift. MARTA represents a key addition in this space because it provides direct metallicities at moderately high oxygen abundances (12+log(O/H) $\sim8.0-8.4$).
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Submitted 12 September, 2025; v1 submitted 4 April, 2025;
originally announced April 2025.
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Classifying spectra of emission-line regions with neural networks -- An application to integral field spectroscopic data of M33
Authors:
Caterina Bracci,
Francesco Belfiore,
Michele Ginolfi,
Anna Feltre,
Filippo Mannucci,
Alessandro Marconi,
Giovanni Cresci,
Elena Bertola,
Alessandro Bombini,
Matteo Ceci,
Cosimo Marconcini,
Bianca Moreschini,
Martina Scialpi,
Giulia Tozzi,
Lorenzo Ulivi,
Giacomo Venturi
Abstract:
Emission-line regions are key to understanding the properties of galaxies, as they trace the exchange of matter and energy between stars and the interstellar medium (ISM). In nearby galaxies, individual nebulae can be identified as HII regions, planetary nebulae (PNe), supernova remnants (SNR), and diffuse ionised gas (DIG) with criteria on single or multiple emission-line ratios. However, these m…
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Emission-line regions are key to understanding the properties of galaxies, as they trace the exchange of matter and energy between stars and the interstellar medium (ISM). In nearby galaxies, individual nebulae can be identified as HII regions, planetary nebulae (PNe), supernova remnants (SNR), and diffuse ionised gas (DIG) with criteria on single or multiple emission-line ratios. However, these methods are limited by rigid classification boundaries, the narrow scope of information they are based upon, and the inability to account for line-of-sight nebular superpositions. In this work, we use artificial neural networks to classify these regions using their optical spectra. Our training set consists of simulated spectra, obtained from photoionisation and shock models, and processed to match observations obtained with MUSE. We evaluate the performance of the network on simulated spectra for a range of signal-to-noise (S/N) levels and dust extinction, and the superposition of different nebulae along the line of sight. At infinite S/N the network achieves perfect predictive performance, while as the S/N decreases, the classification accuracy declines, reaching an average of ~80% at S/N(H$α$)=20. We apply our model to real spectra from MUSE observations of the galaxy M33, where it provides a robust classification of individual spaxels, even at low S/N, identifying HII regions and PNe and distinguishing them from SNRs and diffuse ionized gas, while identifying overlapping nebulae. We then compare the network's classification with traditional diagnostics and find satisfactory agreement. Using activation maximisation maps, we find that at high S/N the model mainly relies on weak lines (e.g. auroral lines of metal ions and He recombination lines), while at the S/N level typical of our dataset the model effectively emulates traditional diagnostic methods by leveraging strong nebular lines.
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Submitted 3 April, 2025; v1 submitted 27 February, 2025;
originally announced February 2025.