arXiv subjects

Adriana Gargiulo

Publications and source records attributed to Adriana Gargiulo.

14 recordsLinked to original sources

arXiv2026

WST -- Wide-field Spectroscopic Telescope: The Next Leap in Wide-field Spectroscopy

The Wide-field Spectroscopic Telescope (WST) is a concept for a dedicated 12-m spectroscopic survey facility designed to address some of the most important questions in astrophysics in the 2040s. The WST will provide unprecedented spectroscopic survey capabilities by operating simultaneously over a 2-degree diameter field of view with 54 low-resolution spectrographs fed by 30,000 fibres, 8-16 high-resolution spectrographs fed by 2,000 fibres, and a large panoramic low-resolution integral-field spectrograph. Supported by Horizon Europe, the concept study has refined the science cases, facility architecture, operations model, sustainability strategy, and technology roadmap. The resulting reference design demonstrates that the WST is both scientifically transformative and technically feasible, while identifying the developments required to mitigate the remaining risks. The WST is designed as an ESO flagship facility for the post-ELT construction era and a key spectroscopic complement to the major imaging, time-domain, and multi-messenger facilities of the coming decades.

astro-ph.IM↗

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↗

arXiv2026

Spectroscopic follow-up of Gaia alerted Young Stellar Object variables: the Large Binocular Telescope view

We analyzed optical/near-IR Large Binocular Telescope spectra of 16 sources alerted by Gaia between 2021 and 2024 due to significant photometric variability. Half of the spectra were taken during quiescence and the rest during a burst or at intermediate brightness. Our analysis of their ten-year light curves and photometric/spectroscopic features provide evidence that all 16 sources are accreting Young Stellar Objects (YSOs). One object, Gaia23bab, is a known EXor source. Other light curves either have peaks over a stable baseline, or significant variability throughout the entire observation period, suggesting multiple contributing processes. All spectra exhibit emission lines from accretion columns, and over half of them show atomic forbidden lines as signatures of outflowing gas. We determined stellar parameters, accretion luminosity (Lacc) and mass accretion rate (Macc) at different brightness phases. Only two sources showed variability primarily due to extinction. During quiescence, our sources exhibit Lacc and Macc values typical of T Tauri and Herbig Ae/Be (HAEBE) sources, supporting the hypothesis that any YSO may undergo episodic accretion. In bursts, the Lacc and Macc of sources with photometric variations exceeding 2 mag follow a shallower relation with stellar luminosity and mass, typical of known EXor sources. This group includes one Class I, one flat-spectrum, and two Class II sources. Notably, the other Class I source, Gaia24beh, shows an Lacc value about ten times higher than typical EXor bursts of the same mass. In the other cases, Lacc and Macc align with variability seen in T Tauri and HAEBE sources.

astro-ph.SR↗

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↗

arXiv2024

The powerful lens galaxy cluster PLCK G287.0+32.9 ($θ_E \sim 43''$)

We present a new high-precision strong lensing model of PLCK G287.0$+$32.9, a massive lens galaxy cluster at $z=0.383$, with the aim to get an accurate estimation of its effective Einstein radius and total mass distribution. We also present a spectroscopic catalog containing accurate redshift measurements for 490 objects, including multiply-lensed sources and cluster member galaxies. We exploit high-quality spectroscopic data from three pointings of the VLT Multi Unit Spectroscopic Explorer, covering a central $3~\rm{arcmin}^2$ region of the cluster. We complete the spectroscopic catalog by including redshift measurements from VLT-VIMOS and KECK-DEIMOS. We identify 129 spectroscopic cluster member galaxies, with redshift values $0.360 \leq z \leq 0.405$ and $m_{\rm{F160W}} \leq 21$, and 24 photometric ones identified with a Convolutional Neural Network from ancillary HST imaging. We also identify 114 multiple images from 28 background sources, of which 84 images from 16 sources are new and the remaining ones were identified in previous work. The best-fitting lens model shows a root mean square separation value between the predicted and observed positions of the multiple images of $0.75''$, corresponding to an improvement in reconstructing the observed positions of the multiple images of a factor of $2.5$ with respect to previous models. Using the predictive power of our new lens model we find 3 new multiple images and we confirm the configuration of three systems of multiple images that were not used for the optimization of the model. The derived total mass distribution confirms this cluster to be a very prominent gravitational lens with an effective Einstein $θ_{E} = 43.4'' \pm 0.1''$, that is in agreement with previous estimates and corresponds to a total mass enclosed in the critical curve of $M_E = {3.33}_{-0.07}^{+0.02} \times{ 10^{14} M_\odot}$.

astro-ph.CO↗

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↗

arXiv2020

The Rapid Build-up of Massive Early-type Galaxies. Supersolar Metallicity, High Velocity Dispersion and Young Age for an ETG at z=3.35

Thanks to very deep spectroscopic observations carried out at the Large Binocular Telescope, we measured simultaneously stellar age, metallicity and velocity dispersion for C1-23152, an ETG at redshift $z$=3.352, corresponding to an epoch when the Universe was $\sim$1.8 Gyr old. The analysis of its spectrum shows that this galaxy, hosting an AGN, formed and assembled $\sim$2$\times$10$^{11}$ M$_\odot$ shaping its morphology within the $\sim$600 Myr preceding the observations, since $z$$\sim$4.6. The stellar population has a mean mass-weighted age 400$^{+30}_{-70}$ Myr and it is formed between $\sim$600 Myr and $\sim$150 Myr before the observed epoch, this latter being the time since quenching. Its high stellar velocity dispersion, $σ_e$=409$\pm$60 km s$^{-1}$, confirms the high mass (M$_{dyn}$=$2.2(\pm0.4)$$\times$10$^{11}$ M$_\odot$) and the high mass density ($Σ_e^{M^*}$=$Σ_{1kpc}=3.2(\pm0.7)\times10^{10}$ M$_\odot$ kpc$^{-2}$), suggesting a fast dissipative process at its origin. The analysis points toward a supersolar metallicity, [Z/H]=0.25$^{+0.006}_{-0.10}$, in agreement with the above picture, suggesting a star formation efficiency much higher than the replenishment time. However, sub-solar metallicity values cannot be firmly ruled out by our analysis. Quenching must have been extremely efficient to reduce the star formation to SFR$<$6.5 M$_\odot$ yr$^{-1}$ in less than 150 Myr. This could be explained by the presence of the AGN, even if a causal relation cannot be established from the data. C1-23152 has the same stellar and physical properties of the densest ETGs in the local Universe of comparable mass, suggesting that they are C1-23152-like galaxies which evolved to $z=0$ unperturbed.

astro-ph.GA↗

arXiv2020

The redshift and the host galaxy of the neutrino candidate 4FGL J0955.1+3551 (3HSP J095507.9+355101)

The BL Lac object 4FGLJ0955.1+3551 has been suggested as a possible source of ultra energetic neutrinos detected by the Icecube observatory. The target was observed in January 2020 at the Large Binocular Telescope. Our spectroscopy (4100-8500 Ang) yields a firm redshift z = 0.557 as deduced by the absorption lines of the host galaxy. The upper limit of the minimum equivalent width on emission lines is 0.3 Ang. From the source image we are able to resolve the host galaxy for which we measure an absolute magnitude M(R) = -22.9 and Re = 8 kpc, that is values which are typical of the host galaxies of BL Lacs.

astro-ph.HE↗

arXiv2019

The space density of z>4 blazars

High redshift blazars are an important class of Active Galactic Nuclei (AGN) that can provide an independent estimate of the supermassive black-hole mass function in high redshift radio-loud AGN without the bias due to absorption along the line-of-sight. Using the Cosmic Lens All Sky Survey (CLASS) we built a complete radio flux-limited sample of high redshift (z>4) blazars suitable for statistical studies. By combining dedicated optical observations and the SDSS spectroscopic database, we obtained a sample of 26 blazar candidates with a spectroscopic redshift above 4. On the basis of their radio spectrum we distinguish between blazars and QSO with a Gigahertz Peaked Spectrum (GPS) like spectrum. Out of the 18 confirmed blazars 14 constitute a completely identified, flux-limited sample down to a magnitude of 21 (AB). Using this complete sample we derive a space density of blazars with 4<z<5.5 of rho=0.13 (+0.05,-0.03) Gpc^-3. This is the first actual estimate of the blazar space density in this range of redshift. This value is in good agreement with the extrapolation of the luminosity function and cosmological evolution based on a sample of flat-spectrum radio quasars selected at lower redshifts and it is consistent with a cosmological evolution peaking at z$\sim$2 similar to radio-quiet QSO. We do not confirm, instead, the presence of a peak at z~4 in the space density evolution, recently suggested using an X-ray selected sample of blazars. It is possible that this extreme peak of the evolution is present only among the most luminous blazars.

astro-ph.GA↗

arXiv2018

The Kormendy Relation of Galaxies in the Frontier Fields Clusters: Abell S1063 and MACS J1149.5+2223

We analyse the Kormendy relations (KRs) of the two Frontier Fields clusters, Abell S1063, at z = 0.348, and MACS J1149.5+2223, at z = 0.542, exploiting very deep Hubble Space Telescope photometry and VLT/MUSE integral field spectroscopy. With this novel dataset, we are able to investigate how the KR parameters depend on the cluster galaxy sample selection and how this affects studies of galaxy evolution based on the KR. We define and compare four different galaxy samples according to: (a) Sérsic indices: early-type ('ETG'), (b) visual inspection: 'ellipticals', (c) colours: 'red', (d) spectral properties: 'passive'. The classification is performed for a complete sample of galaxies with m$_{\textit{F814W}} \le$ 22.5 ABmag (M$_{*}$ $\gtrsim 10^{10.0}$ M$_{\odot}$). To derive robust galaxy structural parameters, we use two methods: (1) an iterative estimate of structural parameters using images of increasing size, in order to deal with closely separated galaxies and (2) different background estimations, to deal with the Intracluster light contamination. The comparison between the KRs obtained from the different samples suggests that the sample selection could affect the estimate of the best-fitting KR parameters. The KR built with ETGs is fully consistent with the one obtained for ellipticals and passive. On the other hand, the KR slope built on the red sample is only marginally consistent with those obtained with the other samples. We also release the photometric catalogue with structural parameters for the galaxies included in the present analysis.

astro-ph.GA↗

arXiv2017

Colour gradients in cluster ellipticals at z~1.4: the hidden content of the galaxy central regions

We present F775W-F850LP (rest-frame UV-U) and F850LP-F160W (rest-frame U-R) colour gradients for a sample of 17 elliptical galaxies morphologically selected in the cluster XMMU J2235.3-2557 at $z$=1.39. We detected significant negative (redder inwards) U-R colour gradients in $\sim$70 per cent of the galaxies and flat gradients for the remaining ones. On the other hand, the UV-U gradients are significant positive (bluer inwards) for $\sim$80 per cent of the galaxies and flat for the remaining ones. Using stellar population synthesis models, we found that the behaviour of the two colour gradients cannot be simultaneously explained by a radial variation of age, metallicity and/or dust. The observed U-R gradients are consistent with a metallicity gradient (mean value $\nabla_{Z} =-0.4$) in agreement with the one observed in the local elliptical galaxies. The positive UV-U gradients cannot be explained with age or metallicity variations and imply an excess of UV emission towards the galaxies' central regions.This excess calls into question mechanisms able to efficiently produce UV emission. The data require either steady weak star formation (< 1 M$_\odot$ yr$^{-1}$) or an He-rich population in the cores of these galaxies in order to simultaneously reproduce both the colour gradients. On the contrary, the presence of a QSO cannot account for the observed UV excess on its own. We discuss these hypotheses on the basis of current observations and available models.

astro-ph.GA↗

arXiv2015

Old age and super-solar metallicity in a massive z~1.4 early-type galaxy from VLT/X-Shooter spectroscopy

We present the first estimate of age, stellar metallicity and chemical abundance ratios, for an individual early-type galaxy at high-redshift (z = 1.426) in the COSMOS field. Our analysis is based on observations obtained with the X-Shooter instrument at the VLT, which cover the visual and near infrared spectrum at high (R >5000) spectral resolution. We measure the values of several spectral absorptions tracing chemical species, in particular Magnesium and Iron, besides determining the age-sensitive D4000 break. We compare the measured indices to stellar population models, finding good agreement. We find that our target is an old (t > 3 Gyr), high-metallicity ([Z/H] > 0.5) galaxy which formed its stars at z_{form} > 5 within a short time scale ~0.1 Gyr, as testified by the strong [α/Fe] ratio ( > 0.4), and has passively evolved in the first > 3-4 Gyr of its life. We have verified that this result is robust against the choice and number of fitted spectral features, and stellar population model. The result of an old age and high-metallicity has important implications for galaxy formation and evolution confirming an early and rapid formation of the most massive galaxies in the Universe.

astro-ph.GA↗

arXiv2014

LBT-LUCIFER spectroscopy: kinematics of a compact early type galaxy at z\simeq1.4

We present a high signal to noise (S/N$>$10) medium resolution (R=2000) LBT-LUCIFER spectrum of the early-type galaxy (ETG) S2F1-142 at $z\simeq1.4$. By means of the CaT line at $8662$ Å, we measured its redshift $z=1.386\pm 0.001$ and we estimated its velocity dispersion $σ_{v}=340 ^{-60}_{+120}$ km/s. Its corresponding virial mass is 3.9$\times10^{11}$ M$_\odot$, compatible with the stellar mass estimates obtained assuming Initial Mass Functions (IMFs) less dwarf rich than the Salpeter one. S2F1-142 is a compact galaxy with $R_{e}$=3.1$\pm$0.2 kpc, i.e., an effective radius more than three times smaller than the average $R_{e}$ of early-type galaxies with the same mass in the local universe. At the same time, we found local and high redshift galaxies with a similar mass content and similar effective radius confirming that it is fully consistent with the already available measures of $R_{e}$ and $σ_{v}$ both in the local and in the distant universe. Considering the distribution of $R_{e}$ and $σ_{v}$ as a function of the stellar mass content of ETGs, both in the local and in the distant universe, we noticed that the measured velocity dispersions of the more compact galaxies are on average slightly lower than expected on the basis of their compactness and the virial theorem, suggesting that {\it i)} their dark matter content is lower than in the more diffuse galaxies and/or {\it ii)} their luminosity profiles are steeper than in the more diffuse galaxies and/or {\it iii)} their larger compactness is an apparent effect caused by the overestimate of their stellar mass content (due to bottom lighter IMF and/or systematic affecting the stellar mass estimates).

astro-ph.GA↗