arXiv subjects

C. Vignali

Publications and source records attributed to C. Vignali.

At least 19 recordsLinked to original sources

arXiv2026

Exploring the AGN population in protoclusters: results from the TNG300 simulation and comparison with observations

In this work, we investigate the physical properties and cosmic evolution of galaxies and AGN in a sample of 280 protoclusters identified in the TNG300 simulation, selected to end up in $z = 0$ clusters with $M_{200, \rm c} > 10^{14} \, {\rm M_{\odot}}$. Our goal is to provide the first statistical view of AGN activity enhancement in a uniformly defined sample of overdense environments, and to identify the physical mechanisms driving it. We identify protoclusters as the progenitors of present-day galaxy clusters through merger-tree reconstruction and compare their galaxy and AGN populations with a control sample of field galaxies across the redshift range $0 \leq z \leq 6$. We investigate galaxy and SMBH demographics, AGN fractions, bolometric luminosity functions, and the SMBH accretion rate density, consistently applying homogeneous selection criteria in all environments. We find that TNG300 protoclusters host systematically more massive galaxies and SMBHs than the field by up to $1 \, {\rm dex}$ at all redshifts, with signatures of accelerated galaxy evolution already visible at $z \sim 3-4$. The AGN fraction increases with stellar mass in both environments and, at fixed host-galaxy stellar mass, is broadly consistent between protoclusters and field galaxies, indicating no strong environmental triggering of SMBH accretion. However, when analysed as a function of redshift, protoclusters exhibit a significant enhancement of AGN activity (by a factor $> 2$), particularly at high luminosities and early cosmic times. We show that this enhancement primarily arises from differences in the stellar-mass distributions of galaxies in overdense regions, where massive systems assemble earlier than in the field. Consistently, protoclusters dominate the bright end of the AGN bolometric luminosity function and contribute up to $\sim 50\%$ of the total SMBH accretion rate density at $z \sim 6$.

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arXiv2026

A new era for Dual AGN science with SHARP

The search for and the characterization of ultra-compact dual active galactic nuclei (AGN) are among the hottest topics of current extragalactic astrophysics. These systems involve two accreting massive black holes (MBHs) embedded within the same host galaxy, with relative projected separations from a few hundred pc down to a few pc. They are central to understanding hierarchical galaxy formation, black hole growth and demographics, and accretion-feedback coupling in the most extreme interaction phases. Even more compellingly, such tight pairs are the most direct precursors of gravitationally bound binary MBHs (sub-pc scale separation), which are among the loudest emitters of gravitational waves (GWs) in the low-frequency ranges. SHARP will deliver the first statistical census and physical characterization of ultra-compact dual AGN up to cosmic distances, finally bridging the observational gap between kpc-scale pairs and sub-pc GW-emitting binaries, and enabling a breakthrough understanding of MBH growth, feedback and co-evolution across cosmic time.

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arXiv2026

Dual AGN and Multiple SMBH Systems in the Era of SKAO

We present a radio-oriented review of current strategies for the detection and characterization of dual active galactic nuclei (DAGN) and supermassive black hole binaries (SMBHBs), emphasizing the crucial role of radio interferometry in advancing this field. We discuss how high-resolution radio imaging - particularly through very long baseline interferometry (VLBI) - provides a unique, dust-unbiased tool to identify multiple accreting SMBHs, disentangle AGN-related emission from star formation, and trace components from tens of kpc to sub-parsec scales. We summarize current observational limitations, such as insufficient sensitivity-resolution combination and area coverage. We then outline how the SKAO will overcome these constraints through its unprecedented combination of sensitivity, survey speed, imaging fidelity and angular resolution, enabling the discovery and characterization of dual and binary SMBHs from the nearby Universe to the epoch of reionization. Several science cases are presented, including radio follow-ups of optical/infrared-selected DAGN, direct blind radio selection of DAGN, studies of compact bound SMBHBs, and the link between SMBHB orbital evolution and low-frequency gravitational wave emission. We further emphasize the synergy between SKAO observations and modern and upcoming facilities such as the James Webb and Euclid space telescopes, Rubin Observatory, and gravitational wave detectors including the Laser Interferometer Space Antenna and pulsar timing arrays. These combined capabilities will allow SKAO to enable the first comprehensive radio census of dual and binary SMBH systems, bridge the gap between electromagnetic and gravitational wave observations, and provide a statistically significant view of SMBH pairing, accretion, and merger-driven feedback throughout cosmic history.

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arXiv2026

The WISSHFUL program: the highest redshift UFO discovered in a non-lensed QSO

We present the first results from the WISSHFUL program, an XMM-Newton heritage program targeting luminous QSOs at Cosmic Noon. We report on recent simultaneous XMM-Newton and NuSTAR observations of the Super-Eddington accreting quasar WISSH13 at z=3.294, which provide the highest quality broadband X-ray spectrum to date for a non-lensed QSO at this redshift. Physical modeling of the continuum reveals a soft photon index ($\Gamma\sim2$) and strong reflection ($R\sim1.4-1.8$), despite the weak narrow Fe emission, and a low high-energy cut-off ($E_{cut}\sim60-80$ keV, $kTe = 15-20$ keV, depending on the model adopted). Most notably, we detect two significant (at $96.7\%$ and $98.9\%$ confidence level, respectively) absorption features at $\sim7.5$ and $\sim10$ keV rest-frame, interpreted as a blueshifted blend of Fe XXV He$\alpha$ and Fe XXVI Ly$\alpha$. These features indicate the presence of two kinematic components of a highly ionized, high column Ultra-Fast Outflow (UFO) with a velocity of $v_{out}\sim0.1c$ and $v_{out}\sim0.3c$, respectively. The slower wind is consistently detected in an archival 2017 XMM-Newton observation, whereas the faster wind is detected only in 2024. This stratified and variable wind exhibits extreme energetics, with a mass outflow rate of $\dot{M}_{out}\sim20M_{\odot}/yr$ (corresponding to $15\% \dot{M}_{acc}$) for each component, and a kinetic power of the order of $\sim1$ and $\sim10\%$ of the bolometric luminosity, respectively. While this represents one of the most powerful UFOs ever detected, its kinetic power is a similar fraction of the QSO's bolometric luminosity compared to lower-redshift AGN. We present several theoretical frameworks to explain the peculiar accretion and ejection properties of this remarkable QSO at Cosmic Noon.

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arXiv2026

Is XRISM/Resolve probing a "raining" absorber in Mrk 509?

X-ray spectroscopy of AGN offers unique insights into the reprocessing of radiationand gas dynamics near SMBH. The Sey 1 galaxy Mrk 509 is an ideal laboratory for these studies since its complex FeK$\alpha$ in emission and the past evidences of transient and fast flows. We present the first high-resolution 2-12 keV spectrum of Mrk 509 obtained with the Resolve calorimeter on-board XRISM, complemented with XMM-Newton and NuSTAR observations to constrain the broadband continuum. We modeled the spectra using self-consistent reflection models for the continuum and emission lines, and photoionized plasma models for the absorption components. The XRISM/Resolve spectrum reveals a narrow FeK$\alpha$ core resolved with $\sigma \sim 10 eV$ (v$_{FWHM} \sim$ 1100 km/s) and a broader component with $\sigma \sim 450 eV$. We also find tentative evidence (3.6$\sigma$) for a ionized absorber. The data suggest that this component is infalling with a velocity of $v_{in} \sim 11000$ km/s and that it is located within few thousands gravitational radii. The narrow FeK$\alpha$ emission is consistent with an origin in the dusty torus, while the broad component arises from the inner BLR or in the accretion disk (R$\sim 30--120 r_g$). Relativistic reflection modeling indictaes the inner edge if the emitting disk to R$\geq 27 r_g$. If confirmed, the high velocity inflow would likely represent fragmented clumps of a "failed wind" raining onto the accretion disk. providing potential direct evidence that non-standard accretion processes coexist with canonical disk-like flows in the inner regions of AGNS.

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arXiv2026

Higher resolution optical spectra of $M_*<10^{10}~M_{\odot}$ galaxies reveal outflow signatures unresolved by the SDSS

Galactic outflows are predicted to be ubiquitous in low-mass galaxies, but observational evidence is lacking. Both a low signal-to-noise and a low spectral resolution can severely hamper the detection of galactic outflows, especially in small galaxies that have intrinsically narrow spectral lines. We obtained new, medium-high resolution (FWHM$_\mathrm{inst}\sim50-110$~km/s) optical spectra of 52 local star forming galaxies ($0.01 < z < 0.03$) with stellar masses $10^{8.5} 10^{-0.74}~\mathrm{M_{\odot}/yr}$). We estimate ionized gas mass outflow rates ranging from $\sim0.1-50\times10^{-3}~\mathrm{M_{\odot}/yr}$ (mean $\sim20\times10^{-3}~\mathrm{M_{\odot}/yr}$) and corresponding mass loading factors between 0.03 and 0.14 (mean $\sim0.07$) for the sample.

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arXiv2026

A XRISM view of the iron line complex in NGC 1068: Rethinking the prototypical Compton-thick AGN

We analyze a XRISM/Resolve observation of NGC1068, focusing on the Fe K$\alpha$ and Fe K$\beta$ fluorescent lines and on the Fe XXV and Fe XXVI emission complexes. Line centroid energies, intrinsic widths, flux ratios, and constraints on the Compton shoulder are derived through local spectral fitting, and compared with atomic calculations and theoretical predictions. The centroid energies of the Fe K$\alpha$ and Fe K$\beta$ lines tightly constrain the emitting material to be neutral or near-neutral. The observed Fe K$\beta$/K$\alpha$ ratio, together with the stringent upper limit on the Compton shoulder ($\lesssim$8--11% of the core flux), disfavour reflection dominated by a homogeneous, classical Compton-thick medium, indicating that most of the neutral Fe K$\alpha$ emission arises in optically thin or moderately Compton-thick gas. The Fe XXV and Fe XXVI emission lines exhibit remarkably large velocity widths, of several thousand km~s$^{-1}$. These broad profiles closely resemble the integrated optical and infrared [O III] and [O IV] lines associated with the large-scale biconical outflow, and are naturally interpreted as the X-ray signature of a more highly ionized, faster, and more spatially confined phase of the same outflow. The iron-K emission of NGC1068 reveals a stratified circumnuclear environment in which neutral and highly ionized components arise in physically distinct regions. The neutral Fe K fluorescence originates predominantly in optically thin or mildly Compton-thick material, despite the persistently Compton-thick line-of-sight obscuration, indicating a geometrically complex cold reprocessor. The highly ionized iron emission lines trace a fast component consistent with a warm bipolar outflow on parsec scales, whose large velocities and inferred energetics suggest that it may represent an efficient channel for feedback in a heavily obscured Seyfert galaxy.

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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

Massive dusty multiphase outflow in local merger shows no sign of slowing on kiloparsec scales

We use ALMA CO(1-0) observations and VLT/MUSE rest-frame optical data of the ultraluminous infrared galaxy (ULIRG) IRAS20100-4156 at $z=0.1297$ to characterize its powerful outflow in multiple phases using tracers of cold molecular, ionized, and neutral atomic gas and dust as well. Our analysis uses the correspondence with the stellar velocity field to split the complex emission line profiles of the CO(1-0) line into components in gravitational and non-gravitational motion. We find a massive ($8\times10^{9}\,M_\odot$) molecular outflow containing about 40% of the total molecular gas mass in the system. The outflow shows a bi-conical morphology centered on the brightest galaxy in the merger, oriented along its minor axis and extending to $\sim5\,\mathrm{kpc}$. This outflow has a characteristic velocity of $170\,\mathrm{km/s}$, an outflow mass rate of $700\,M_\odot/\mathrm{yr}$, a depletion time of $16\,\mathrm{Myr}$, and energetics consistent with star formation as a driver. The neutral atomic and ionized gas phases traced by NaI absorption and H$\alpha$ emission show counterparts to the blueshifted cold molecular outflow but are only 15% and 3% as massive. None of the three gas phases show any signs of slowing down over the extent at which we detected the outflow, suggesting an acceleration mechanism acting on the outflowing gas at kiloparsec scales. We also detect $3.5\times 10^7\,M_\odot$ of dust, traced by optical extinction in the MUSE data, in the blueshifted outflowing cold molecular gas. The ionization state of the non-outflowing gas is consistent with star formation, while the outflowing component shows shock-like ionization. We conclude that the multiphase outflow in IRAS20100-4156 originates in the southeast nucleus of the merger and is driven by the starburst activity there, with radiation pressure likely playing a significant role in its acceleration.

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arXiv2025

ESO Expanding Horizons White Paper: Electromagnetic counterparts of massive BH mergers with LISA

The Laser Interferometer Space Antenna (LISA), adopted by ESA and scheduled for the second half of the next decade, will drive a new revolution in the rapidly growing field of gravitational-wave astronomy, by extending GW observations into the hiterto unexplored millihertz regime. One of the key source classes of LISA is merging massive black hole binaries in the 1e4-1e7 Msun mass range detectable to very high redshifts $z\sim 15$. MBHBs lighter than 1e6 Msun can potentially be identified during their inspiral weeks before coalescence, allowing for complementary electromagnetic observations before, during, and after the two MBHs merge. This white paper aims at defining the optimal strategy to maximize the number of detected EM counterparts of LISA MBHB events.

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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

A deep X-ray look to the most obscured quasar at z~3.6 and its environment

The most luminous and obscured quasars (QSOs) detected in infrared all-sky surveys could represent a key co-evolutionary phase from nuclear to circum-galactic (CG) scales in the formation of massive galaxies. In this context, Hot Dust Obscured Galaxies (Hot DOGs) at z ~2-4 provide a unique opportunity to study the link between cosmic mass assembly and nuclear accretion in high-z luminous QSOs/galaxies. W0410-0913 (hereafter W0410-09) is a luminous ($\rm ~L_{\rm bol} \sim 6.4 \times10^{47} \rm erg\ s^{-1}$) obscured QSO at z = 3.631, with a 30 kpc CG Ly$\alpha$ nebula (CGLAN), smaller than the ~ 100 kpc nebulae around unobscured Type-I QSOs, and an exceptional overdense environment of ~ 19 Ly$\alpha$ emitters (LAEs) within 300 kpc and $\pm$ 200 $\rm km ~s^{-1}$ of the Hot DOG. We aim to detect and characterize nuclear accretion in W0410-09 and its environment. Exploiting a deep proprietary ~280 ks Chandra observation, using empirical and physically motivated models for obscured sources, we show that W0410-09 exhibits Compton-thick obscuration ($\rm~ N_H > 10^{24} \rm cm^{-2}$) and high intrinsic luminosity ($\rm ~L_{2-10} > 10^{45} \rm erg ~s^{-1}$), making it one of the most luminous obscured QSOs at z $>$ 3.5. With the exclusion of W0410-09 we do not detect X-ray emission from any of the 19 LAEs, except for a 3$\sigma$ signal in the 6-7 keV rest-frame band, interpreted as Fe K$\alpha$ emission, suggesting the presence of heavily obscured yet undetected AGN emission in several LAEs. Including W0410-09, the estimated AGN fraction is $f_{\rm AGN}^{\rm LAE} = 5^{+12}_{-4}$%, potentially up to ~35% if unresolved obscured AGN are considered as suggested by the Fe K$\alpha$ line detection. We conclude that W0410-09 is in a critical transitional blow-out phase, during which powerful QSO-driven outflows are clearing the nuclear obscuration, ultimately leading to an unobscured luminous quasar.

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arXiv2025

XRISM/Resolve reveals the complex iron structure of NGC 7213: Evidence for radial stratification between inner disk and broad-line region

We present the first high-resolution X-ray spectrum of NGC 7213 obtained with XRISM/Resolve, supported by simultaneous XMM-Newton, NuSTAR, and SOAR optical data. The XRISM spectrum resolves the neutral Fe\,K$\alpha$ into two components: a narrow core ($\rm FWHM = 650_{-220}^{+240}\,\rm km\,s^{-1}$) consistent with emission at the dust sublimation radius, and a broader, asymmetric line best described by disk-like emission from $\sim 100\,\rm R_{g}$. This disk component mirrors the profile of the double-peaked H$\alpha$ line observed in the optical. In addition, we detect broadened Fe XXV and Fe XXVI emission lines whose inferred locations bridge the gap between the inner disk and the optical broad-line region. The weak narrow Fe K$\alpha$ equivalent width ($\rm EW = 32 \pm 6\,eV$) and absence of a Compton hump imply a low-covering-fraction, Compton-thin torus. Together, these results reveal a radially stratified structure in NGC 7213, spanning nearly four orders of magnitude in radius, and place the source in an intermediate accretion state ($\rm \lambda_{Edd} = 0.001-0.01$) where the inner disk and BLR remain, while the torus shows signs of dissipation.

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arXiv2025

Investigating the mysterious nature of 1LHAASO J1740+0948u through deep XMM-Newton observations

1LHAASO J1740+0948u is a very-high-energy (VHE) source reported by LHAASO, with no counterpart at other wavelengths. It is located at 0.2{\deg} from PSR J1740+1000, a radio and gamma-ray pulsar placed well above the Galactic plane, which displays an X-ray tail. Despite the offset, the association between the two sources is likely. We aim to study the diffuse X-ray emission around PSR J1740+1000 and its tail to investigate the origin of 1LHAASO J1740+0948u through a multi-wavelength SED fitting, testing different scenarios. We analysed ~500 ks of XMM-Newton observations and studied for the first time the diffuse emission around the pulsar. We also analysed the tail and how its emission evolves as a function of distance. We then performed a fit of the SED, including the spectrum of 1LHAASO J1740+0948u and the X-ray data obtained from either the analysis of the tail or the diffuse emission, to understand whether one of the two X-ray sources could be related to the TeV emission and attempt a source classification. The diffuse X-ray emission analysis resulted in upper limits in the 0.5-10 keV range. The tail is best fitted with a power law with $\Gamma=1.76\pm0.06$ in 0.5-8 keV, with no significant detection of spectral variations with distance. We do not find a good SED fit that can explain both the X-ray tail and the LHAASO spectrum with reasonable parameters, suggesting that the TeV emission likely comes from an older X-ray-faint electron population. We then performed an SED fitting of the VHE spectrum combined with the upper limits on the diffuse emission, constraining the magnetic field to be as low as $B\leq1.2 \mu$G. We suggest that 1LHAASO J1740+0948u could represent either the relic PWN of PSR J1740+1000 or its pulsar halo. Our energy density results hint at a halo-like nature for 1LHAASO J1740+0948u, but deeper multi-wavelength observations are required to confirm this hypothesis.

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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 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

X-ray investigation of possible super-Eddington accretion in a radio-loud quasar at $z=6.13$

We present radio and X-ray observations of the recently discovered $z=6.13$ radio-powerful quasar RACS J032021.44$-$352104.1 using uGMRT, ATCA, LBA, and Chandra. The observed radio properties are in line with what is typically observed in high-$z$ radio quasars ($\alpha_{\rm r}=0.72\pm 0.02$ and L$_{\rm 1.4GHz}=5.8 \pm 0.9 \times 10^{26}$ W Hz$^{-1}$). Despite the relatively low X-ray flux observed $F_{\rm 0.5-7.0 keV}=2.3\pm0.5 \times 10^{-14}$ erg sec$^{-1}$ cm$^{-2}$, the intrinsic luminosity in the 2-10 keV rest frame is markedly high, $L_{\rm 2-10 keV}=1.8^{+1.1}_{-0.7} \times 10^{46}$ erg sec$^{-1}$, making RACS J032021.44$-$352104.1 one of the most luminous quasars currently known at $z>5.5$. The high X-ray luminosity is largely driven by an extrapolation to energies below the observable X-ray window with Chandra and the slope derived in the 0.5-7 keV band (or 3.5--50 keV in the rest-frame; $\Gamma_{\rm X}=3.3\pm0.4$). By analysing the overall spectral energy distribution of the quasar we found that the remarkably soft X-ray emission: (1) cannot be produced by relativistic jets, even when relativistic boosting is considered; and (2) is consistent with expectations for a super-Eddington accreting SMBH. If such a high accretion rate was confirmed, this source would be a unique laboratory to study high accretion in the early Universe and could help resolve some challenges inherent in early black hole growth paradigms.

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