arXiv subjects

Giustina Vietri

Publications and source records attributed to Giustina Vietri.

9 recordsLinked to original sources

arXiv2026

Unveiling the Cosmic Dawn with SHARP: Probing extended Lyman-$α$ nebulae in a Universe less than 600 Myr old

The existence of luminous quasars just a few hundred million years after the Big Bang challenges our understanding of both black hole growth and galaxy formation and evolution. These objects harbour supermassive black holes exceeding a billion solar masses (M$_{BH} > 10^{9} M_{\odot}$) by redshift $z\sim 6.5$-$7.5$, powered by extreme gas accretion. At the same time, their host galaxies are also undergoing intense star formation, consuming gas at the rate of hundreds of solar masses per year. Characterising the circumgalactic medium (CGM) and intergalactic medium (IGM) surrounding high-redshift quasars becomes an essential tool to understand the conditions that enable the rapid formation and evolution of these extreme sources. While in the last decades spatially resolved observations in the optical band have targeted CGM through Ly$α$ nebulae surrounding $z \sim 2-6$ quasars, current instrumental limitations hamper observations of high-z ($z>8$) quasars that will be discovered by Euclid/Roman/LSST surveys. Despite the large fraction of neutral hydrogen at the epoch of reionisation, in the last decade several surprising Ly$α$ detections have been obtained from sources deep in the epoch of reionisation. The unprecedented collecting area of ELT, coupled with the resolution and wavelength coverage of SHARP, specifically VESPER, will enable us to map for the first time $z>9$ Ly$α$ emission down to the structures of size $\sim$150 pc, while simultaneously capturing their large-scale structure up to 100 kpc for the first time at this redshift. This will allow a major and long-awaited step forward in the exploration of quasars and galaxies formation and evolution deep in the epoch of reionisation.

astro-ph.GA↗

arXiv2026

A SHARP Look at Quenching and Bulge-Disk Growth in Massive Galaxies at Cosmic Noon

The physical mechanisms that quench star formation in massive galaxies remain poorly understood. At cosmic noon (1 3x sharper than JWST) and broad near-IR wavelength coverage with 12-IFU multiplexing. This will enable, for the first time, a simultaneous bulge-disk decomposition of stellar populations and spatially resolved mapping of ionised gas in massive galaxies (log $M_*/M_{\odot}\geq 11$) at 2.2 15-20 per spectral resolution element, on the inner bulge, and outer disk extracted spectral continuum, and S/N>5 for nebular lines ([OII], H$β$, [OIII], H$α$) on sub-kpc scales. These observations will allow us to reconstruct independent bulge and disk star-formation histories, ages, metallicities, and $α$-enhancements, while mapping spatially resolved star formation, gas kinematics, and feedback-driven outflows. By directly comparing the timing of bulge growth and star-formation suppression across galaxy components, this programme will test whether quenching proceeds inside-out, distinguish fast and slow quenching pathways, and link structural transformation to feedback processes in the most massive galaxies at cosmic noon.

astro-ph.GA↗

arXiv2025

Connecting disc-corona physics and ionised outflows in AGN in the 2040s

We outline a science case for next-generation wide-field spectroscopic surveys aimed at connecting the physics of the accretion disc and X-ray corona in active galactic nuclei (AGN) with the properties of their nebular regions and circumgalactic medium (CGM). We focus on the non-linear Lx-Luv relation and on deviations from this canonical coupling encoded in $Δα_{OX}$, the offset of the optical-to-X-ray index from the mean relation, and propose to use broad and narrow line emission and CGM nebulae as calorimeters of the ionising SED to trace different accretion "states". We propose an observational strategy based on rest-frame UV/optical spectroscopy of $\sim 10^{4}-10^{5}$ AGN, a time-domain reverberation-mapping tier for a well-defined subsample, coordinated X-ray coverage, and wide-field IFU mapping of CGM emission (including H$α$ and Ly$α$). From these goals we derive requirements for a future ESO facility in the 2040s: a dedicated, wide-field, high-multiplex optical-NIR spectroscopic telescope with time-domain flexibility and arcmin-scale IFU capability.

astro-ph.IM↗

arXiv2025

The evolution of obscured AGN across cosmic time -- A large quasar survey for the 2040s

We propose a large quasar demographic optical multi-object spectroscopic (MOS) survey targeting over 50 million AGN candidates up to the highest redshifts possible in the optical (z~6.5), with repeat visits, using a variety of selection criteria available by 2040. A large MOS survey combining all AGN selection methods is the only way to unify a diverse range of different obscured AGN populations within a single, variability- and spectroscopy-based framework, rather than as disjoint classes selected by different methods.

astro-ph.GA↗

arXiv2025

An Extremely-High Velocity Outflow in SMSS J2157-3602, the most luminous quasar in the first 1.3 Gyr

We report the discovery of an extremely high-velocity outflow (EHVO) in the most luminous ($L\rm_{Bol}$ $\sim$ 2.29 $\times$ 10$^{48}$ erg/s) QSO, SMSS J2157-3602, at z=4.692. Combined XSHOOTER and NIRES observations reveal that the EHVO reaches a maximum velocity of v$_\mathrm{max} \sim 0.13c$ and persists over rest-frame timescales of a few months to one year. SMSS J2157-3602 also exhibits one of the highest balnicity index discovered in an EHVO so far. In addition, the blueshifted CIV emission traces a high-velocity (v$\rm_{CIV}^{50}\sim$ 4660 km/s) outflow from the broad-line region. Thanks to an XMM-Newton observation, we also discover the X-ray weak nature of this QSO, which likely prevents the overionization of the innermost disk atmosphere and facilitates the efficient launch of the detected EHVO and BLR winds. The extraordinary luminosity of SMSS J2157-3602 and the extreme velocity of the EHVO make it a unique laboratory for testing AGN driven feedback under extreme conditions. Current uncertainties on the outflow's location and column density strengthen the case for dedicated follow-up, which will be essential to assess the full feedback potential of this remarkable quasar.

astro-ph.GA↗

arXiv2023

Radio WISSH: tuning on the most luminous quasars in the Universe

In the past years, the results obtained by the WISSH quasar project provided a novel general picture on the distinctive multi-band properties of hyper-luminous ($L_{bol}>10^{47}$ erg/s) quasars at high redshift (z$\sim$2-4), unveiling interesting relations among active galactic nuclei, winds and interstellar medium, in these powerful sources at cosmic noon. Since 2022, we are performing a systematic and statistically-significant VLA study of the radio properties of WISSH. We carried out high-resolution VLA observations aiming at: 1) identifying young radio source from the broad-band spectral shape of these objects; 2) sample an unexplored high redshift/high luminosity regime, tracking possible evolutionary effects on the radio-loud/radio-quiet dichotomy; 3) quantifying orientation effects on the observed winds/outflows properties.

astro-ph.HE↗

arXiv2022

SIPGI: an interactive pipeline for spectroscopic data reduction

SIPGI is a spectroscopic pipeline for the data reduction of optical/near-infrared data acquired by slit-based spectrographs. SIPGI is a complete spectroscopic data reduction environment retaining the high level of flexibility and accuracy typical of the standard "by-hand" reduction methods but with a significantly higher level of efficiency. This is obtained exploiting three main concepts: 1) a built-in data organiser to classify the data, together with a graphical interface; 2) the instrument model (analytic description of the main calibration relations); 3) the design and flexibility of the reduction recipes: the number of tasks required to perform a complete reduction is minimised, preserving the possibility to verify the accuracy of the main stages of data-reduction process. The current version of SIPGI manages data from the MODS and LUCI spectrographs mounted at the Large Binocular Telescope (LBT) with the idea to extend SIPGI to support other through-slit spectrographs.

astro-ph.IM↗

arXiv2022

The WISSH quasars project XI. The mean Spectral Energy Distribution and Bolometric Corrections of the most luminous quasars

Hyper-luminous Quasi-Stellar Objects (QSOs) represent the ideal laboratory to investigate Active Galactic Nuclei (AGN) feedback mechanism since their formidable energy release causes powerful winds at all scales and thus the maximum feedback is expected. We aim at deriving the mean Spectral Energy Distribution (SED) of a sample of 85 WISE-SDSS Selected Hyper-luminous (WISSH) quasars. Since the SED provides a direct way to investigate the AGN structure, our goal is to understand if quasars at the bright end of the luminosity function have peculiar properties compared to the bulk of the population. We built a mean intrinsic SED after correcting for the dust extinction, absorption and emission lines and intergalactic medium absorption. We also derived bolometric, IR band and monochromatic luminosities together with bolometric corrections at lambda = 5100 A and 3 micron. We define a new relation for the 3 micron bolometric correction. We find that the mean SED of hyper-luminous WISSH QSOs is different from that of less luminous sources, i.e. a relatively lower X-ray emission and a near and mid IR excess which can be explained assuming a larger dust contribution. WISSH QSOs have stronger emission from both warm and very hot dust, the latter being responsible for shifting the typical dip of the AGN SED from 1.3 to 1.1 micron. We also derived the mean SEDs of two sub-samples created according to the presence of Broad Absorption Lines and equivalent width of CIV line. We confirm that BALs are X-ray weak and that they have a reddened UV-optical continuum. We also find that BALs tend to have stronger emission from the hot dust component. This analysis suggests that hyper-luminous QSOs have a peculiar SED compared to less luminous objects. It is therefore critical to use SED templates constructed exclusively from very bright quasars samples when dealing with particularly luminous sources.

astro-ph.GA↗

arXiv2021

Capturing dual AGN activity and kiloparsec-scale outflows in IRAS 20210+1121

The most accepted scenario for the evolution of massive galaxies across cosmic time predicts a regulation based on the interplay between AGN feedback, which injects large amounts of energy in the host environment, and galaxy mergers, being able to trigger massive star formation events and accretion onto the supermassive black holes. Interacting systems hosting AGN are useful laboratories to get key insights into both phenomena. In this context, we present the analysis of the optical spectral properties of IRAS 20210+1121 (I20210), a merging system at $z = 0.056$. According to X-ray data, this object comprises two interacting galaxies, each hosting an obscured AGN. The optical spectra confirm the presence of AGN features in both galaxies. In particular, we are able to provide a Seyfert classification for I20210 North. The spectrum of I20120 South shows broad blueshifted components associated with the most intense emission lines that indicate the presence of an ionized outflow, for which we derive a maximum velocity of $\sim$2000 km s$^{-1}$, an extension of $\sim$2 kpc and a mass rate of $\sim$0.6 M$_\odot$ yr$^{-1}$. We also report the existence of an ionized nebular component with $v \sim 1000$ km s$^{-1}$ at $\sim$6.5 kpc Southwards of I20210 South, that can be interpreted as disrupted gas ejected from the host galaxy by the action of the outflow. I20120 therefore exhibits a double obscured AGN, with one of them showing evidence of ongoing events for AGN-powered outflows. Future spatially-resolved spectroscopy will allow to accurately map on the gas kinematics in this AGN pair and evaluate the impact of the outflow on both the interstellar medium and galaxy environment.

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