arXiv subjects

C. Vignali

Publications and source records attributed to C. Vignali.

At least 91 records · Page 5Linked to original sources

arXiv2022

The WISSH quasars project X. Discovery of a multi-component and highly-variable UV ultra-fast outflow in a z=3.6 quasar

We report on the variability of a multi-component broad absorption line (BAL) system observed in the hyper-luminous quasar J1538+0855 at z=3.6. Observations from SDSS, VLT, LBT and Subaru telescopes taken at five different epochs, spanning 17 yr in the observed frame, are presented. We detect three (A, B, C) CIV variable troughs exhibiting extreme velocities ($\sim$40,000-54,000 km s$^{-1}$) similar to the ultra-fast outflows (UFOs) typically observed in the X-ray spectra. The A component of the BAL UFO ($\rm v_{ufo}$ $\sim$0.17 c) shows strength variations, while B ($\rm v_{ufo}$ $\sim$0.15 c) and C ($\rm v_{ufo}$ $\sim$0.13 c) components show changes both in shape and strength, appearing and disappearing at different epochs. In addition, during the last observation on June 2021 the entire BAL system disappears. The variability trends observed during the first two epochs (1.30 yr rest-frame) in the CIV, SiIV, OVI and NV absorption spectral regions are the same for B and C troughs, while the A component of the BAL varies independently. This suggests a change in the ionization state of the absorbing gas for B and C components and tangential motion for the A component, as causes of this temporal behavior. Accordingly, it is possible to provide an upper limit for distance of the gas responsible for the A component of $R\rm_{out}^{A}$$\le$58 pc, and in turn, a kinetic power of $\dot{E}\rm_{K,ufo}$ $\le$5.2 $\times$ 10$^{44}$ erg s$\rm^{-1}$. We also obtain $R\rm_{out}^{B,C}$ $\le$2.7 kpc for B and C components, which implies an upper limit estimation of $\dot{E}\rm_{K,ufo}$ $\le$2.1$\times$10$^{46}$ erg s$\rm^{-1}$ and $\dot{E}\rm_{K,ufo}$ $\le$1.4$\times$10$^{46}$ erg s$\rm^{-1}$, respectively. Future spectral monitoring with high-resolution instruments is mandatory to accurately constrain physical properties of the BAL UFO discovered in the UV spectrum of J1538+0855.

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arXiv2022

The properties of the X-ray corona in the distant ($z=3.91$) quasar APM 08279+5255

We present new joint XMM-Newton and NuSTAR observations of APM 08279+5255, a gravitationally-lensed, broad-absorption line quasar ($z=3.91$). After showing a fairly stable flux ($f_{\rm2-10}\simeq4-5.5\times10^{-13}\rm~erg~s^{-1}$) from 2000 to 2008, APM 08279+5255 was found in a fainter state in the latest X-ray exposures ($f_{\rm2-10}\simeq2.7\times10^{-13}\rm~erg~s^{-1}$), which can likely be ascribed to a lower X-ray activity. Moreover, the 2019 data present a prominent Fe K$α$ emission line and do not show any significant absorption line. This fainter state, coupled to the first hard X-ray sampling of APM 08279+5255, allowed us to measure X-ray reflection and the high-energy cutoff in this source for the first time. From the analysis of previous XMM-Newton and Chandra observations, X-ray reflection is demonstrated to be a long-lasting feature of this source, but less prominent prior to 2008, possibly due to a stronger primary emission. The estimated high-energy cutoff ($E_{\rm cut}=99_{-35}^{+91}$ keV) sets a new redshift record for the farthest ever measured and places APM 08279+5255 in the allowed region of the compactness-temperature diagram of X-ray coronae, in agreement with previous results on high-$z$ quasars.

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arXiv2022

The molecular gas properties in local Seyfert 2 galaxies

We present a multi-wavelength study of the molecular gas properties of a sample of local Seyfert 2 galaxies to assess if, and to what extent, the presence of an active galactic nucleus (AGN) can affect the Interstellar Medium (ISM) properties in a sample of 33 local Seyfert 2 galaxies. We compare the molecular gas content (MH2), derived from new and archival low-J CO line measurements of a sample of AGN and a control sample of star-forming galaxies (SFGs). Both the AGN and the control sample are characterised in terms of host-galaxy properties (e.g., stellar and dust masses, Mstar and Mdust, respectively; and star formation rate, SFR). We also investigate the effect of AGN activity onto the emission of polycyclic aromatic hydrocarbon (PAH) molecules in the mid-infrared (MIR), a waveband where the dust-reprocessed emission from the obscured AGN contributes the most. The AGN hosted in less massive galaxies (i.e., log(Mstar/Msun)<10.5; log(Mdust/Msun)<7.5) show larger molecular gas content with respect to SFGs matched in stellar and dust mass. When comparing their depletion time(tdep~MH2/SFR), AGN show tdep~0.3-1.0 Gyr, similar to those observed in the control sample of SFGs. Seyfert 2 galaxies show fainter PAH luminosity at increasingly larger dominance of the nuclear activity in the MIR. We find no clear evidence for a systematic reduction of the molecular gas reservoir at galactic scale in Seyfert galaxies with respect to SFGs. This is in agreement with recent studies showing that molecular gas content only is reduced in regions of sub-kpc size, where the emission from the accreting supermassive black hole dominates. Nonetheless, we show that the impact of AGN activity on the ISM is clearly visible as suppression of the PAH luminosity.

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arXiv2021

Short time-scale X-ray spectral variability in the Seyfert 1 galaxy NGC 3783

We report on the X-ray time resolved spectral analysis of XMM-Newton observations of NGC 3783. The main goal is to detect transient features in the Fe K line complex, in order to study the dynamics of the innermost accretion flow. We reanalize archival observations of NGC 3783, a bright local AGN, for which a transient Fe line was reported, complementing this data set with new available observations. This results in a long set of observations which can allow us to better assess the significance of transient features and possibly test their recurrence time. Moreover, since the new data catch the source in an obscured state, this analysis allows also to test whether the appearance/disappearance of transient features is linked to the presence of obscuring gas. We detect discrete features at the >=90% significance level both in emission and in absorption at different times of the observations, split into 5ks time-resolved spectra. The overall significance of individual features is higher in the obscured dataset. The energy distribution of the detections changes between the two states of the source, and the features appear to cluster at different energies. Counting the occurrences of emission/absorption lines at the same energies, we identify several groups of $\geq3σ$ detections: emission features in the 4-6 keV band are present in all observations and are most likely due to effects of the absorber present in the source; an emission line blend of neutral Fe K$β$/ionized Fe Ka is present in the unobscured dataset; absorption lines produced by gas at different ouflowing velocities and ionization states show an increase in energy between the two epochs, shifting from ~6 keV to ~6.7-6.9 keV. The representation of the features in a time-energy plane via residual maps highlighted a possible modulation of the Fe Ka line intensity, linked to the clumpiness of the absorbing medium.

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arXiv2021

Multi-Wavelength Study of a Proto-BCG at z = 1.7

In this work we performed a spectral energy distribution (SED) analysis in the optical/infrared band of the host galaxy of a proto-brightest cluster galaxy (BCG, NVSS J103023+052426) in a proto-cluster at z = 1.7. We found that it features a vigorous star formation rate (SFR) of ${\sim}$570 $\mathrm{M_{\odot}}$/yr and a stellar mass of $M_{\ast} \sim 3.7 \times 10^{11}$ $\mathrm{M_{\odot}}$; the high corresponding specific SFR = $1.5 \pm 0.5$ $\mathrm{Gyr^{-1}}$ classifies this object as a starburst galaxy that will deplete its molecular gas reservoir in $\sim$ $3.5 \times 10^8$ yr. Thus, this system represents a rare example of a proto-BCG caught during the short phase of its major stellar mass assembly. Moreover, we investigated the nature of the host galaxy emission at 3.3 mm. We found that it originates from the cold dust in the interstellar medium, even though a minor non-thermal AGN contribution cannot be completely ruled out. Finally, we studied the polarized emission of the lobes at 1.4 GHz. We unveiled a patchy structure where the polarization fraction increases in the regions in which the total intensity shows a bending morphology; in addition, the magnetic field orientation follows the direction of the bendings. We interpret these features as possible indications of an interaction with the intracluster medium. This strengthens the hypothesis of positive AGN feedback, as inferred in previous studies of this object on the basis of X-ray/mm/radio analysis. In this scenario, the proto-BCG heats the surrounding medium and possibly enhances the SFR in nearby galaxies.

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arXiv2021

Simulating infrared spectro-photometric surveys with a SPRITZ

Mid- and far-infrared (IR) photometric and spectroscopic observations are fundamental to a full understanding of the dust-obscured Universe and the evolution of both star formation and black hole accretion in galaxies. In this work, using the specifications of the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) as a baseline, we investigate the capability to study the dust-obscured Universe of mid- and far-IR photometry at 34 and 70 $μ$m and low-resolution spectroscopy at 17-36 $μ$m using the state-of-the-art Spectro-Photometric Realisations of Infrared-selected Targets at all-z (SPRITZ) simulation. This investigation is also compared to the expected performance of the Origins Space Telescope and the Galaxy Evolution Probe. The photometric view of the Universe of a SPICA-like mission could cover not only bright objects (e.g. L$_{IR}$>10$^{12}$L$_\odot$) up to z=10, but also normal galaxies(L$_{IR}$<10$^{11}$L$_\odot$) up to z$\sim$4. At the same time, the spectroscopic observations of such mission could also allow us to estimate the redshifts and study the physical properties for thousands of star-forming galaxies and active galactic nuclei by observing the polycyclic aromatic hydrocarbons and a large set of IR nebular emission lines. In this way, a cold, 2.5-m size space telescope with spectro-photometric capability analogous to SPICA, could provide us with a complete three-dimensional (i.e. images and integrated spectra) view of the dust-obscured Universe and the physics governing galaxy evolution up to z$\sim$4.

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arXiv2021

XXL-HSC: An updated catalogue of high-redshift ($z\geqslant3.5$) X-ray AGN in the XMM-XXL northern field. Constraints on the bright end of the soft logN-logS

X-rays offer a reliable method to identify Active Galactic Nuclei (AGN). However, in the high-redshift Universe X-ray AGN are poorly sampled due to their relatively low space density and the small areas covered by X-ray surveys. In addition to wide-area X-ray surveys, it is important to have deep optical data in order to locate the optical counterparts and determine their redshifts. In this work, we build a high-redshift ($z\geqslant3.5$) X-ray selected AGN sample in the XMM-XXL northern field using the most updated [0.5-2 keV] catalogue along with a plethora of new spectroscopic and multi-wavelength catalogues, including the deep optical Subaru Hyper Suprime-Cam (HSC) data reaching magnitude limits i$\sim$26 mag. We select all the spectroscopically confirmed AGN and complement this sample with high-redshift candidates that are HSC g- and r-band dropouts. To confirm the dropouts, we derive their photometric redshifts using spectral energy distribution techniques. We end up with a sample of 54 high-z sources (28 with spec-z), the largest in this field so far (almost three times larger than in previous studies), and we estimate the possible contamination and completeness. We calculate the number counts (logN-logS) in different redshift bins and compare our results with previous studies and models. We provide the strongest high-redshift AGN constraints yet at bright fluxes ($\rm f_{0.5-2~keV} > 10^{-15} erg~s^{-1}~cm^{-2}$). The samples of $z\geqslant3.5$, $z\geqslant4$ and $z\geqslant5$ are in agreement with an exponential decline model similar to that witnessed at optical wavelengths. Our work emphasizes the importance of using wide area X-ray surveys with deep optical data to uncover high redshift AGN.

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arXiv2021

X-ray spectroscopic survey of highly-accreting AGN

Improving our understanding of the nuclear properties of high-Eddington ratio ($λ_\mathrm{Edd}$) active galactic nuclei (AGN) is necessary since the bulk of X-ray spectroscopic studies have been focused on low-Eddington AGN. We present here the X-ray spectral analysis of 14 radio-quiet, $λ_\mathrm{Edd}\gtrsim1$ AGN at $0.4\leq z \leq 0.75$, observed with XMM-Newton. Optical/UV data from simultaneous Optical Monitor observations have been also considered. These AGN have been selected to have relatively high values of black hole mass ($M_\mathrm{BH}\sim10^{8-8.5}M_\odot$) and bolometric luminosity ($L_\mathrm{bol} \sim 10^{46}$ erg s$^{-1}$), in order to complement previous studies of high-Eddington AGN at lower $M_\mathrm{BH}$ and $L_\mathrm{bol}$. We studied the relation between $λ_\mathrm{Edd}$ and other key X-ray spectral parameters, such as the photon index of the power-law continuum $Γ$, the X-ray bolometric correction $k_\mathrm{bol,X}$ and $α_\mathrm{ox}$. Despite the homogeneous optical and SMBH accretion properties, the X-ray properties of these high-Eddington AGN are quite heterogeneous. We measured values of $Γ$ comprised between 1.3 and 2.5, at odds with the expectations based on previously reported $Γ-λ_\mathrm{Edd}$ relations, by which $Γ\geq2$ would be an ubiquitous hallmark of AGN with $λ_\mathrm{Edd}\sim1$. We found that $\sim30\%$ of the sources are X-ray weak, with an X-ray emission about a factor of $\sim10-80$ fainter than that of typical AGN at similar UV luminosities. The X-ray weakness seems to be intrinsic and not due to intervening obscuration. This may indicate that high-Eddington AGN commonly undergo periods of intrinsic X-ray weakness. Furthermore, results from a follow-up monitoring with Swift of one of these X-ray weak AGN suggest that these periods can last for several years.

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arXiv2021

SUPER. VI. A giant molecular halo around a z~2 quasar

We present the discovery of copious molecular gas in the halo of cid_346, a $z=2.2$ quasar studied as part of the SINFONI survey for Unveiling the Physics and Effect of Radiative feedback (SUPER). New Atacama Compact Array (ACA) CO(3-2) observations detect a much higher flux (by a factor of $14\pm5$) than measured on kiloparsec scales ($r\lesssim8$ kpc) using previous snapshot Atacama Large Millimeter/submillimeter Array data. Such additional CO(3-2) emission traces a structure that extends out to $r\sim200$ kpc in projected size, as inferred through direct imaging and confirmed by an analysis of the uv visibilities. This is the most extended molecular circumgalactic medium (CGM) reservoir that has ever been mapped. It shows complex kinematics, with an overall broad line profile (FWHM $= 1000$ km/s) that is skewed towards redshifted velocities up to at least $v\sim1000$ km/s. Using the optically thin assumption, we estimate a strict lower limit for the total molecular CGM mass observed by ACA of $M_{mol}^{CGM}>10^{10}~M_{\odot}$. There is however room for up to $M^{CGM}_{mol}\sim 1.7\times 10^{12}$ $M_{\odot}$, once optically thick CO emission with $α_{\rm CO}=3.6$ $\rm M_{\odot}~(K~km~s^{-1}~pc^2)^{-1}$ and $L^{\prime}_{CO(3-2)}/L^{\prime}_{CO(1-0)}=0.5$ are assumed. Since cid_346 hosts quasar-driven ionised outflows and since there is no evidence of merging companions or an overdensity, we suggest that outflows may have played a crucial rule in seeding metal-enriched, dense gas on halo scales. However, the origin of such an extended molecular CGM remains unclear.

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arXiv2021

Compton-Thick AGN in the NuSTAR era VI: The observed Compton-thick fraction in the Local Universe

We present the analysis of simultaneous NuSTAR and XMM-Newton data of 8 Compton-thick (CT-) active galactic nuclei (AGN) candidates selected in the Swift-Burst Alert Telescope (BAT) 100 month survey. This work is part of an ongoing effort to find and characterize all CT-AGN in the local ($z\leq$0.05) Universe. We used two physically motivated models, MYTorus and borus02, to characterize the sources in the sample, finding 5 of them to be confirmed CT-AGN. These results represent an increase of $\sim19$% over the previous NuSTAR-confirmed, BAT-selected CT-AGN at $z\leq0.05$, bringing the total number to 32. This corresponds to an observed fraction of $\sim 8$\% of all AGN within this volume-limited sample, although it increases to $20\pm5$% when limiting the sample to $z\leq0.01$. Out of a sample of 48 CT-AGN candidates, selected using BAT and soft (0.3$-$10 keV) X-ray data, only 24 are confirmed as CT-AGN with the addition of the NuSTAR data. This highlights the importance of NuSTAR when classifying local obscured AGN. We also note that most of the sources in our full sample of 48 Seyfert 2 galaxies with NuSTAR data have significantly different line-of-sight and average torus column densities, favouring a patchy torus scenario.

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arXiv2021

An ALMA view of 11 Dusty Star Forming Galaxies at the peak of Cosmic Star Formation History

We present the ALMA view of 11 main-sequence DSFGs, (sub-)millimeter selected in the GOODS-S field, and spectroscopically confirmed to be at the peak of Cosmic SFH (z = 2-3). Our study combines the analysis of galaxy SED with ALMA continuum and CO spectral emission, by using ALMA Science Archive products at the highest spatial resolution currently available for our sample (< 1 arcsec). We include galaxy multi-band images and photometry (in the optical, radio and X-rays) to investigate the interlink between dusty, gaseous and stellar components and the eventual presence of AGN. We use multi-band sizes and morphologies to gain an insight on the processes that lead galaxy evolution, e.g. gas condensation, star formation, AGN feedback. The 11 DSFGs are very compact in the (sub-)millimeter (median r(ALMA) = 1.15 kpc), while the optical emission extends tolarger radii (median r(H)/r(ALMA) = 2.05). CO lines reveal the presence of a rotating disc of molecular gas, but we can not exclude either the presence of interactions and/or molecular outflows. Images at higher (spectral and spatial) resolution are needed to disentangle from the possible scenarios. Most of the galaxies are caught in the compaction phase, when gas cools and falls into galaxy centre, fuelling the dusty burst of star formation and the growing nucleus. We expect these DSFGs to be the high-zstar-forming counterparts of massive quiescent galaxies. Some features of CO emission in three galaxies are suggestive of forthcoming/ongoing AGN feedback, that is thought to trigger the morphological transition from star-forming disks to ETGs.

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arXiv2021

X-ray sources in the 1.75 Ms Ultra Narrow Deep Field observed by XMM-Newton

In this work we present the results of the survey carried out on one of the deepest X-ray fields observed by the XMM-Newton satellite. The 1.75 Ms Ultra Narrow Deep Field (XMM175UNDF) survey is made by 13 observations taken over 2 years with a total exposure time of 1.75 Ms (1.372 Ms after flare-filtered) in a field of $30' \times 30' $ centered around the blazar 1ES 1553+113. We stacked the 13 observations reaching flux limits of $4.03 \times 10^{-16} $, $1.3 \times 10^{-15}$, and $9.8 \times 10^{-16}\, erg\, s^{-1}\, cm^{-2}$ in the soft $(0.2 - 2\, \mathrm{keV})$, hard $(2 - 12\, \mathrm{keV})$, and full $(0.2 - 12\, \mathrm{keV})$ bands, respectively. Using a conservative threshold of Maximum Likelihood significance of $ML \geq 6$, corresponding to $3σ$, we detected 301 point-sources for which we derived positions, fluxes in different bands, and hardness ratios. Thanks to an optical follow-up carried out using the 10.4m the Gran Telescopio Canarias (GTC) on the same field in the $u'g'r'i'z'$ bands, combined with WISE/2MASS IR data; we identified 244 optical/IR counterpart candidates for our X-ray sources and estimated their X-ray luminosities, redshift distribution, X-ray/optical $-$ X-ray/IR flux ratios, and absolute magnitudes. Finally, we divided this subsample in 40 non-active sources and 204 AGNs, of which 139 are classified as Seyfert galaxies and 41 as Quasars.

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arXiv2021

The XMM-SERVS survey: XMM-Newton point-source catalogs for the W-CDF-S and ELAIS-S1 fields

We present the X-ray point-source catalogs in two of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields, W-CDF-S (4.6 deg$^2$) and ELAIS-S1 (3.2 deg$^2$), aiming to fill the gap between deep pencil-beam X-ray surveys and shallow X-ray surveys over large areas. The W-CDF-S and ELAIS-S1 regions were targeted with 2.3 Ms and 1.0 Ms of XMM-Newton observations, respectively; 1.8 Ms and 0.9 Ms exposures remain after flare filtering. The survey in W-CDF-S has a flux limit of 1.0 $\times$ 10$^{-14}$ erg cm$^{-2}$ s$^{-1}$ over 90% of its area in the 0.5-10 keV band; 4053 sources are detected in total. The survey in ELAIS-S1 has a flux limit of 1.3 $\times$ 10$^{-14}$ erg cm$^{-2}$ s$^{-1}$ over 90% of its area in the 0.5-10 keV band; 2630 sources are detected in total. Reliable optical-to-IR multiwavelength counterpart candidates are identified for $\approx$ 89% of the sources in W-CDF-S and $\approx$ 87% of the sources in ELAIS-S1. 3186 sources in W-CDF-S and 1985 sources in ELAIS-S1 are classified as AGNs. We also provide photometric redshifts for X-ray sources; $\approx$ 84% of the 3319/2001 sources in W-CDF-S/ELAIS-S1 with optical-to-NIR forced photometry available have either spectroscopic redshifts or high-quality photometric redshifts. The completion of the XMM-Newton observations in the W-CDF-S and ELAIS-S1 fields marks the end of the XMM-SERVS survey data gathering. The $\approx$ 12,000 point-like X-ray sources detected in the whole $\approx$ 13 deg$^2$ XMM-SERVS survey will benefit future large-sample AGN studies.

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arXiv2021

The role of SPICA-like missions and the Origins Space Telescope in the quest for heavily obscured AGN and synergies with Athena

In the BH-galaxy co-evolution framework, most of the star-formation (SF) and the black hole (BH) accretion is expected to take place in highly obscured conditions. Thus, obscured AGN are difficult to identify in optical or X-ray bands, but shine bright in the IR. Moreover, X-ray background (XRB) synthesis models predict that a large fraction of the yet-unresolved XRB is due to the most obscured (Compton thick, CT) of these AGN. In this work, we investigate the synergies between putative IR missions (using SPICA, proposed for ESA/M5 but withdrawn in October 2020, and Origins Space Telescope, OST, as `templates') and the X-ray mission Athena, which should fly in early 2030s, in detecting and characterizing AGN, with a particular focus on the most obscured ones. Using an XRB synthesis model, we estimated the number of AGN and the number of those which will be detected in the X-rays. For each AGN we associated an optical-to-FIR SED from observed AGN with both X-ray data and SED decomposition, and used these SEDs to check if the AGN will be detected by SPICA-like or OST at IR wavelengths. We expect that, with the deepest Athena and SPICA-like (or OST) surveys, we will be able to detect in the IR more than $90\,\%$ of all the AGN (down to L$_{2-10\text{keV}} \sim 10^{42}\,$erg/s and up to $z \sim 10$) predicted by XRB synthesis modeling, and we will detect at least half of them in the X-rays. Athena will be extremely powerful in detecting and discerning moderate- and high-luminosity AGN. We find that the most obscured and elusive CT-AGN will be exquisitely sampled by SPICA-like mission or OST and that Athena will allow a fine characterization of the most-luminous ones. This will provide a significant step forward in the process of placing stronger constraints on the yet-unresolved XRB and investigating the BH accretion rate evolution up to very high redshift ($z \ge 4$).

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arXiv2021

Simulating the infrared sky with a Spritz

Current hydrodynamical and semi-empirical simulations of galaxy formation and evolution have difficulties in reproducing the number densities of IR-detected galaxies. Therefore, a versatile, phenomenological new simulation tool is necessary to reproduce current and predict future observations at IR wavelengths. In this work we generate simulated catalogues starting from the Herschel infrared luminosity functions of different galaxy populations, in order to consider in a consistent way different populations of galaxies and active galactic nuclei. We associated a spectral energy distribution and physical properties, such as stellar mass, star-formation-rate and AGN contribution, to each simulated galaxy using a broad set of empirical relations. We compare the resulting simulated galaxies, extracted up to z$=$10, with a broad set of observational relations. The Spectro-Photometric Realisations of Infrared-selected Targets at all-z (SPRITZ) simulation will allow us to obtain in a fully consistent way simulated observations for a broad set of current and future facilities with photometric capabilities as well as low-resolution IR spectroscopy, like the James Webb Space Telescope (JWST) or the Origin Space Telescope (OST). The derived simulated catalogue contains galaxies and active galactic nuclei that by construction reproduce the observed IR galaxy number density, but it is also in agreement with the observed number counts from UV to far-IR wavelengths, the observed stellar mass function, the star-formation-rate vs. stellar mass plane and the luminosity function from the radio to the X-ray. The proposed simulation is therefore ideal to make predictions for current and future facilities, in particular, but not limited to, those operating at IR wavelengths. The SPRITZ simulation will be publicly available.

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arXiv2021

Connecting X-ray nuclear winds with galaxy-scale ionised outflows in two $z\sim1.5$ lensed quasars

Outflows driven by active galactic nuclei (AGN) are expected to have a significant impact on the host galaxy evolution, but it is still debated how they are accelerated and propagate on galaxy-wide scales. This work addresses these questions by studying the link between X-ray, nuclear ultra-fast outflows (UFOs) and extended ionised outflows, for the first time in two quasars close to the peak of AGN activity ($z\sim2$), where AGN feedback is expected to be more effective. As targets, we selected two multiple-lensed quasars at $z\sim1.5$, HS 0810+2554 and SDSS J1353+1138, known to host UFOs and observed with the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematical analysis of the [O III]$λ$5007 optical emission line, in order to trace the presence of ionised outflows. We detected spatially resolved ionised outflows in both galaxies, extended more than 8 kpc and moving up to $v>2000$ km/s. We derived mass outflow rates of $\sim$12 M$_{sun}$/yr and $\sim$2 M$_{sun}$/yr for HS 0810+2554 and SDSS J1353+1138. Comparing with the co-hosted UFO energetics, the ionised outflow energetics in HS 0810+2554 is broadly consistent with a momentum-driven regime of wind propagation, while in SDSS J1353+1138 it differs by a factor of $\sim$100 from theoretical predictions, requiring either a massive molecular outflow or a high variability of the AGN activity to account for such a discrepancy. By additionally considering our results with those from the small sample of well-studied objects (all local but one), with both UFO and extended (ionised/atomic/molecular) outflow detections, we found that in 10 out of 12 galaxies the large-scale outflow energetics is consistent with the theoretical predictions of either a momentum- or an energy-driven scenario. This suggests that such models explain relatively well the acceleration mechanism of AGN-driven winds on large scales.

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arXiv2021

A possible sub-kiloparsec dual AGN buried behind the galaxy curtain

Although thousands of galaxy mergers are known, only a handful of sub-kiloparsec-scale supermassive black hole (SMBH) pairs have been confirmed so far, leaving a huge gap between the observed and predicted numbers of such objects. In this work, we present a detailed analysis of the Sloan Digital Sky Survey optical spectrum and of near-infrared (NIR) diffraction limited imaging of SDSS~J1431+4358. This object is a local radio-quiet type 2 active galactic nucleus (AGN) previously selected as a double AGN candidate on the basis of the double-peaked [OIII] emission line. The NIR adaptive optics-assisted observations were obtained at the Large Binocular Telescope with the LUCI+FLAO camera. We found that most of the prominent optical emission lines are characterized by a double-peaked profile, mainly produced by AGN photoionization. Our spectroscopical analysis disfavors the hypothesis that the double-peaked emission lines in the source are the signatures of outflow kinematics, leaving open the possibility that we are detecting either the rotation of a single narrow-line region or the presence of two SMBHs orbiting around a common central potential. The latter scenario is further supported by the high-spatial resolution NIR imaging: after subtracting the dominant contribution of the stellar bulge component in the host galaxy, we detect two faint nuclear sources at r<0.5 kpc projected separation. Interestingly, the two sources have a position angle consistent with that defined by the two regions where the [OIII] double peaks most likely originate. Aside from the discovery of a promising sub-kiloparsec scale dual AGN, our analysis shows the importance of an appropriate host galaxy subtraction in order to achieve a reliable estimate of the incidence of dual AGNs at small projected separations.

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arXiv2020

SUPER IV. CO(J=3-2) properties of active galactic nucleus hosts at cosmic noon revealed by ALMA

Feedback from AGN is thought to be key in shaping the life cycle of their host galaxies by regulating star-formation activity. Therefore, to understand the impact of AGN on star formation, it is essential to trace the molecular gas out of which stars form. In this paper we present the first systematic study of the CO properties of AGN hosts at z~2 for a sample of 27 X-ray selected AGN spanning two orders of magnitude in AGN bolometric luminosity (Lbol= 10^44.7-10^46.9 erg/s) by using ALMA Band 3 observations of the CO(3-2) transition (~1" angular resolution). To search for evidence of AGN feedback on the CO properties of the host galaxies, we compared our AGN with a sample of inactive (i.e., non-AGN) galaxies from the PHIBSS survey with similar redshift, stellar masses, and SFRs. We used the same CO transition as a consistent proxy for the gas mass for the two samples in order to avoid systematics involved when assuming conversion factors. By adopting a Bayesian approach to take upper limits into account, we analyzed CO luminosities as a function of stellar masses and SFRs, as well as the ratio LCO(3-2)/M* (proxy for the gas fraction). The two samples show statistically consistent trends in the LCO(3-2)-Lfir and LCO(3-2)-M* planes. However, there are indications that AGN feature lower CO(3-2) luminosities (0.4-0.7 dex) than inactive galaxies at the 2-3sigma level when we focus on the subset of parameters where the results are better constrained and on the distribution of the mean LCO(3-2)/M*. Therefore, even by conservatively assuming the same excitation factor r31, we would find lower molecular gas masses in AGN, and assuming higher r31 would exacerbate this difference. We interpret our result as a hint of the potential effect of AGN activity (e.g., radiation and outflows), which may be able to heat, excite, dissociate, and/or deplete the gas reservoir of the host galaxies. (abridged)

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