WST - the Wide-field Spectroscopic Telescope: surveying the Universe in the 2040’s and beyond

10 Mar 2025, 14:00 → 12 Mar 2025, 18:00 Europe/Rome

Auditorium Nazionale "Ernesto Capocci" (INAF - Osservatorio Astronomico di Capodimonte)

 

 

 

Monday 10 March

Introduction and Welcome

1 Introduction and Welcome

Speaker: Pietro Schipani (Istituto Nazionale di Astrofisica (INAF))

Schipani_WST_Welcome.pdf

2 In memory of Bianca Garilli

Speaker: Marco Scodeggio (Istituto Nazionale di Astrofisica (INAF))

Bianca_WST_Workshop_Napoli.pdf

The Wide-field Spectroscopic Telescope

3 WST: context and Italian participation

Speaker: Dr Maria Sofia Randich (Istituto Nazionale di Astrofisica (INAF))

WST-italian-Randich.pdf

4 WST: Status and plans

Speaker: Roland Bacon

Bacon_2025-03-INAF-Naples.pdf

5 The WST science drivers: transformational science in the 2040s

The ambitious concept of WST has its root and motivation in science. WST will be able to address outstanding scientific questions in the areas of cosmology; galaxy assembly, evolution, and enrichment, including our own Milky Way; origin of stars and planets; time domain and multi-messenger astrophysics.
I will present an overview of the scientific drivers already identified by the science team and presented in the first WST science white paper (Mainieri et al. 2024). I will also stress the fact that in the coming years there is an important opportunity to contribute to further refine and shape the science drivers for WST.

Speaker: Vincenzo Mainieri (ESO)

WST-Naples-INAF-Mainieri.pdf

6 Expanding Horizons: Transforming Astronomy in the 2040s

The European Southern Observatory (ESO) is dedicated to consistently transforming the scientific landscape by designing, building and operating ground-based observatories that push technology to new heights and expand our knowledge of the cosmos. ESO’s Extremely Large Telescope (ELT) follows in the footsteps of the 10-year-old collaborative efforts of the Atacama Large Millimeter/submillimeter Array (ALMA), which remains the most powerful facility capable of studying the cold Universe, and ESO’s 25-year-old Very Large Telescope (VLT), which remains at the global forefront of visible-light astronomy.
Now ESO is looking to the future: what breakthroughs in astronomy will we make in the 2040s and beyond?
With Expanding Horizons, ESO will search for its next innovative ground-based programme. We aim to identify the next transformational facility that will advance humanity’s understanding of the Universe whilst fostering international collaboration.

Speaker: Mariya Lyubenova

Lyubenova_ESO_ExpH_032025_WST.pdf

16:05 Coffee Break

The landscape

7 INAF Landscape

Speaker: Isabella Pagano (INAF)

2025-03-10WSTPagano.pdf

8 The Scientific Landscape in the 2040+

Speaker: Marcella Marconi (Istituto Nazionale di Astrofisica (INAF))

Marconi_WST.pptx.pdf

9 Are there valuable synergies between CTAO and WST?

Very-high-energy (VHE) gamma-ray astroparticle physics is a relatively young field, and observations over the past decade have surprisingly revealed almost 250 VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known - such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming facility, and its potential scientific exploitation. In particular, this contribution will highlight the scientific cases that could benefit from synergies with a large-field-of-view optical spectrograph.

Speaker: Roberta Zanin (Istituto Nazionale di Astrofisica (INAF))

20250310_NapoliWST_Zanin_v2.pdf

10 The SKA Observatory: perspectives and synergies with the WST

A panchromatic approach is essential for a comprehensive understanding of the Universe and its constituents. Only through observations along the entire range of the electromagnetic spectrum it is possible to get a full census of the physical (thermal and non-thermal) processes regulating star formation and nuclear activities in galaxies, as well as of the various galaxy components (stars, multi-phase gas, dust, relativistic plasma).
In this presentation I will give a brief overview the SKA project and its scientific perspectives. I will then highlight the potential benefits of a synergistic use of the SKA Observatory and WST, focusing on the role that WST spectroscopic surveys can play in supporting next-generation radio continuum and atomic hydrogen (HI) surveys.

Speaker: Dr Isabella Prandoni (Istituto Nazionale di Astrofisica (INAF))

Prandoni_WST25_final_print_STILES.pdf

Tuesday 11 March

Origin of the Solar System, planets, stars and the Milky Way

11 Investigation of Solar System objects with WST

The optical band is an interesting spectral region to explore the solar system objects. In this range,
indeed, it is possible to investigate properties of several molecules that are of interest for comets and
distant objects, like Kuiper Belt Objects (KBOs).
WST, in its present configuration, allows one to cover emissions from a list of radicals, including CN,
N2
+, CO+, C2, NH2, and OI, that are relevant to provide indication on the relative abundance of parental
molecules, in comets. As an example, N2

• and CO+ can be used to infer the relative N2 and CO content,
  which is finally a very sensitive indicator of their formation temperatures, only studied on a few objects
  so far. On the other hand, by extending the wavelength coverage to 300 nm, it would be possible to study
  the water outgassing taking advantage of the very bright OH (0-0) emission band around 310 nm
  (Snodgrass et al., 2017).
  Triton, Pluto and possibly the KBOs, another class of solar system objects that can be studied with
  WST, are thought to have a similar surface composition, rich in volatile ices, including N2, H2O, CO2,
  CO, and CH4 (Buratti et al. 1994; Quirico et al. 1999; Cruikshank et al. 2000; Grundy and Young,
  2004; Grundy et al. 2010; Demeo et al., 2010), and dominated by N2. Thanks to the monitoring efforts
  using ground-based observations in the visible and near-infrared, short (Hicks and Buratti, 2004) and
  long-term variability (Grundy and Young, 2004) of the major components have been reported for
  Triton. Of particular interest is the use of CH4 bands to investigate the surface composition and help
  predicting the seasonal evolution of volatile species across the surface.
  In this work, we explore the capabilities of WST to investigate the surface composition of comets and
  KBOs. The strength point of WST for the solar system objects investigation is the use of the 300-400
  nm range, not covered by any of the future giant telescopes, which will permit to investigate most of
  the radical produced by the surface sublimation on comets. In addition, the advantage of the large
  Field of View of WST will allow to possibly setting up a survey of a wide number of KBOs, with a
  twofold purpose: enlarge the number of KBO spectrally characterized, allowing a statistical spectral
  study of the distant Solar System, and provide a reliable sample for a comparative investigation with
  the Triton surface composition.
  The use of WST for these science topics will burst our knowledge on KBOs and comets, particularly in
  the Comet Interceptor era.

Speaker: Alessandra Migliorini (INAF)

MiglioriniA.pdf

12 Towards the characterization of planet-host stars with WST from future missions: the case of Ariel

Most of our current understanding of planet formation mechanisms is based on the correlations of stellar parameters with planet frequency and planet properties. In the advent of new missions dedicated to planet detection in vast numbers, the precise and uniform characterization of the host population is crucial. The WST is the ideal instrument to observe planet hosts from Gaia (tens of thousands planets expected in 2030), Nancy Grace Roman Space Telescope (tens of thousands planets), and PLATO (a few thousand). High-resolution spectroscopy is key to infer stellar parameters and abundances of elements important for planet formation. The WST with its wide wavelength coverage, high resolution (R~40000), and MOS capabilities is suited to fulfill this goal in particular for the thousands of faint hosts which cannot be followed up in high resolution by other facilities.

In this talk, I will present the strategy for the characterization of planet hosts to be observed by the Ariel space mission. This work combines ground-based observation campaigns and detailed spectroscopic analysis techniques in high resolution for a sample of 358 planet hosts so far. The lessons learnt from the synergy between the Ariel mission and ground-based spectroscopic facilities for the planet-host characterization can also be applied to WST.

Our analysis furthermore, reveals the connection of planetary properties with the different Galactic disc populations. In particular, we find that giant planets are more frequent around more metal-rich stars that belong to the Galactic thin disc, while lower-mass planets are found in more metal-poor environments and are more frequent in the thick disc, thus orbiting older stars. Our results highlight the importance of Galactic chemical evolution, although often overlooked, on the current distribution of planets.

Speaker: Maria Tsantaki (Istituto Nazionale di Astrofisica (INAF))

WST_MTsantaki.pdf

13 Young stellar populations: the origin of stars and planets

Star and planet formation are complex phenomena, whose outcomes depend on physical processes occurring across a wide range of scales. This complexity is reflected in the diverse phenomena that characterize the early pre-main sequence phase of stars and their disks, including gas accretion onto the central star, rapid and collimated jets, steady and slow outflows, and intense, rapidly variable magnetic activity. Furthermore, the early evolution of pre-main sequence stars, the dispersal of their disks, and the planet formation process can be significantly influenced by the surrounding environment through mechanisms such as external photoevaporation and close stellar encounters.
In this talk, I will provide a brief overview of the properties of pre-main sequence stars and their disks, the impact of the star-forming environment on their evolution, and the importance of large-scale surveys for their study. Additionally, I will discuss how WST will contribute to the study of pre-main sequence stars and their disks across various star-forming regions in the Milky Way and nearby galaxies.

Speaker: Mario Giuseppe Guarcello (Istituto Nazionale di Astrofisica (INAF))

Guarcello_WSTmeeting_Naples_March2025.pdf

14 Tracing the Evolution of Young Stellar Populations with the Wide-field Spectroscopic Telescope

Young stellar populations hold the key to understanding the early phases of star formation, the impact of stellar feedback, and the processes that shape galactic structure over time. By mapping the kinematics and chemical compositions of stars across different environments, we can trace their origins, dynamical evolution, and eventual dispersal into the field. The WST will provide an unprecedented opportunity to study these populations on a large scale, enabling us to connect their formation conditions to their long-term evolution.

In this talk, I will discuss how WST will revolutionize our understanding of young stellar populations by probing their motion, chemical signatures, and interactions with their surroundings. I will also highlight the key instrumental requirements necessary to achieve these goals, including the resolution and the radial velocity precision
for kinematic measurements. Additionally, I will explore the potential for extending the instrument into the infrared, which would enhance our ability to study embedded young stars and populations in highly extincted regions. These advancements will open new pathways for understanding the fundamental processes driving star formation and galactic evolution.

Speaker: Giuseppe Germano Sacco (Istituto Nazionale di Astrofisica (INAF))

WST_YS_Sacco.pdf

15 Exploiting large multiplex spectroscopic surveys of young clusters with neural networks

Most of what we know of the first stages of stellar evolution and planet formation is derived from observations of young stars in the Solar Neighborhood, yet most stars and planetary systems form in clusters, and there is evidence that the Solar System itself formed in a clustered environment. In the last decades, we have progresed significantly in our understanding of star formation in clusters, mostly through photometric studies. VLT instruments have allowed us to start to probe spectroscopically the evolution of stars and star-disk interaction in clusters, especially the sensitivity and spectral coverage of MUSE is now allowing us to begin to probe the effect of cluster environment on disk accretion as well as photoevaporative winds in clusters. Understanding these processes is essential to assess disk survivability in clusters and their potential to form planetary systems. In this talk I will show the promise and limits shown by our VLT/MUSE programmes to study stellar photospheres and disk-star interaction in clusters, and will discuss the promise of WST in this field. One specific challenge that we have already encountered and addressed in our VLT/MUSE survey is the challenge of spectrally analyse samples composed of many thousand of spectra. For this purpose we developed a technique based on model-trained conditional Invertible Neural Networks. The use of these techniques will become essential with the next generation of spectrscopic surveyors, such as the WST. I will describe the methodology that we developed and the successes we obtained in the processing and analysis of large VLT/MUSE mosaics and the potential of extending this technique to future WST surveys.

Speaker: Dr Da Eun Kang (UniBo)

DaeungKang.pdf

16 Three-dimensional structure and chemo-dynamical evolution of the Milky Way

Galactic studies are currently undergoing a renaissance, thanks to the wealth of data from the Gaia satellite and ground-based surveys. Stellar positions, motions and chemical abundances have been mapped with unprecedented detail. Vertical disturbances, streaming motions, wave-like features and arches in the velocity space have been revealed on a large scale, triggering new interest and questions into the physical mechanisms regulating the dynamical evolution of the Galaxy. At the same time, significant progress has been made towards the mapping of stars in configuration space, opening a new window on the large-scale spiral structure of the Milky Way. In this talk, I will give an update on the latest results about the structure and chemo-dynamical evolution of the Milky Way. I will also discuss future perspectives, and what we hope to learn in the coming years about the Milky Way and its place in the Universe thanks to WST and upcoming stellar surveys.

Speaker: Eloisa Poggio (INAF - Osservatorio Astrofisico di Torino)

Poggio_Presentation_WSTmeeting.pdf

17 Tracing Milky Way spiral arms with High-Resolution spectroscopy of Classical Cepheids

Classical Cepheids (DCEPs) are crucial for calibrating the extragalactic distance ladder, ultimately enabling the determination of the Hubble constant through the period-luminosity (PL) and period-Wesenheit (PW) relations that they exhibit. The purpose of the C-MetaLL survey is to understand how the PL and PW relations depend on metallicity. The DCEPs are also very important tracers of the young populations placed along the Galactic disc. Our goal is to extend the range of measured metallicities towards the metal-poor regime to cover the parameter space better. To this end, we observed objects in a wide range of Galactocentric radii, allowing us to study in detail the abundance gradients present in the Galactic disc.
The sample presented is composed of a total of 292 pulsators, whose spectra were obtained with a variety of high-resolution spectrographs, analysed in a homogeneous way and published in the context of the C-MetaLL survey. For each target, we derived accurate atmospheric parameters, radial velocities, and abundances for up to 29 different species. The iron abundances range between 0.5 and −1 dex with a rather homogeneous distribution in metallicity. These data were used to study the abundance gradients of the Galactic disc in a range of Galactocentric radii (RGC) spanning the range of 5-20 kpc. For most of the elements, we have found a clear negative gradient, with a slope of −0.064 ± 0.003 dex kpc−1 for the [Fe/H] case.
Through a qualitative fit with the Galactic spiral arms, we show how our farthest targets ( RGC >10 kpc) trace both the Norma-Outer and the extension of the Outer-Scutum-Centaurus arms. The possible association of our targets with the two spiral arms could justify the sensible change of abundance trend for some of the elements analysed. These results show the great potential of high-resolution spectroscopy in constraining and characterizing the spiral structures, especially in regions still poorly explored.

Speaker: Erasmo Trentin (Istituto Nazionale di Astrofisica (INAF))

Trentin.pdf

10:50 Coffee Break

Variable objects and their role as tracers of galaxy structure and evolution

18 Synergies between Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) and WST

In this talk, I will review the status of Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), now approaching the First Light, expected soon in 2025. I will discuss the organization of the international Science Collaborations, also emphasizing the role of the in-kind contributions of international teams, as but not limited to those of the European community. In particular, I will focus on the Transients and Variable Stars Science Collaboration activities and the Galactic Plane science, highlighting the synergies with WST in this context

Speaker: Sara Bonito

BonitoFinaleWeb.pdf

19 Novelty and value of WST in the context of time-domain astronomy

Time-domain and multi-messenger astronomy are key priorities identified by major planning exercises, such as the Astro2020 decadal survey. All current and upcoming facilities together can follow up only a few percent of the expected transient alerts, while WST will enable maximum operational flexibility and rapid data processing in order to support the under-characterized transient sky and phenomena. The upcoming investment in deep survey imaging with dedicated facilities promises many unforeseen scientific discoveries in this area: e.g., the Rubin LSST facility will undertake a nightly scan leading to a ‘real time video’ of the southern sky. However, spectroscopic follow-up is key to delivering this extraordinary scientific bounty. In this talk, I will give a review of the Astro2020 decadal survey and why characterizing astronomical objects in a homogeneous way with the same instrument and large sky coverage is of utmost importance in the modern/future landscape of astronomy and what makes WST still novel and unique in this context, even after the advent of 4-meter class telescopes such as 4MOST and WEAVE poised to follow-up time-variable sources.

Speaker: Dr Fatemeh Zahra Majidi (Postdoc fellow at the University of Padova)

WST_time_domain_FZMajidi.pdf

20 WST and the Variable Sky

The variable sky offers a large number of different phenomena, from transient/explosive to periodic ones. The proposed capabilities of WST will have a huge impact in characterizing the physical mechanisms behind them. In this talk I will propose different topics, with focus on variable stars. Pulsating stars such as RR Lyrae and Cepheids (Classical, Anomalous, Type II) are wonderful population tracers that allow to constrain the star formation history, chemical evolution, and accretion history of the host galaxy. With this respect, WST will allow to characterize RR Lyrae stars over a large range of distances, complementing photometric surveys such as LSST, thus characterizing the early phases of the main component of the Milky Way and Nearby Galaxies. Moreover, WST will have a strong impact in the determination of distances, through the derivation of abundances for both young and old pulsating stars.

Speaker: Dr Matteo Monelli (INAF - Osservatorio di Roma)

monelli_11III25_WST_naples.pdf

21 A New Bayesian Method for Analyzing the Structure of the Galactic Bulge Using δ Scuti Stars

The Galactic bulge, the densely populated central region of the Milky Way, extends a few kilo-parsecs vertically above and below the Galactic plane. This region is pivotal for understanding the formation and evolutionary history of our Galaxy. Key to this understanding are the structural parameters of the bulge. Classical pulsators, such as RR Lyrae stars, Miras, and δ Scuti stars, are abundant in this region. Due to their well-defined period-luminosity relations, these stars serve as excellent distance indicators, enabling precise mapping of the Galactic bulge. Furthermore, combining WST's spectroscopic data with precise present/upcoming photometry of pulsating stars will allow for an unprecedented three-dimensional mapping of the Galactic bulge, shedding new light on its formation and evolution. We have developed a new methodology in the Bayesian framework to investigate the structure of the bulge using only photometric data.
I intend to present an overview of these findings based on our recent publication https://doi.org/10.1093/mnras/stac1596 and highlight the future directions of this work.

Speaker: Dr Mami Deka (Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astronomico di Capodimonte)

Deka WST talk.pdf

22 RR Lyrae Guiding WST in Unraveling Local Universe History

The RR Lyrae stars have proven to be a fundamental tool for investigating the history of the Universe, serving as both distance indicators and witnesses to ancient merging events that shaped the Milky Way.
Thanks to the large diameter, field of view and multiplexing of WST, it will be possible to observe for the first time in high-resolution spectroscopy a large number of distant (>100 kpc) RR Lyrae stars both in the extreme periphery of the Galaxy and in many dwarf satellites of the Local Group. These observations will be the perfect follow-up for the upcoming large photometric optical (e.g. Rubin LSST) and space (Euclid/Roman Telescopes) facilities which will discover and characterize thousands of new RR Lyrae variables in the quoted environments.
The WST products, including abundance measurement of iron, alpha and neutron capture elements, as well as accurate radial velocities, will be fundamental to determining the three positional and three velocities for these objects thanks to precise proper motions up to G=20.5-21.0 provided by Gaia DR5 in 2030 and accurate distances through Period-Luminosity-Metallicity relations. This wealth of data will allow us to determine more accurately the orbits of the RR Lyrae variables and study the dynamics of these objects, linking them to ancient merging events. At the same time, the alpha and neutron capture elements will allow us to use chemical tagging to confirm such associations.

Speaker: Emanuela Luongo (Istituto Nazionale di Astrofisica (INAF))

Luongo WST talk.pdf

23 Exploring Star Formation Histories in Local Group Galaxies: A Deeper Perspective with the WST

The star formation histories (SFHs) in Local Group dwarf galaxies give essential insights into their evolution and interaction with the environment that help us understand their role into the formation of large structures. Resolved stellar populations, analyzed through the synthetic Color-Magnitude Diagram (CMD) method, have been pivotal in reconstructing detailed SFHs. The Wide Spectroscopic Telescope (WST), with its unique combination of high multiplexing capability, wide field of view, and spectral resolution will have the ability to survey Local Group dwarf galaxies beyond the Milky Way’s virial radius in systems previously inaccessible to detailed study. WST will deliver precise chemical abundances and kinematic information for millions of stars that will allow the calibration of key SFH indicators, such as age-sensitive abundance ratios ("chemical clocks"), the frequency of binary systems in different environments, while providing detailed chemical inventories for diverse stellar populations.

Speaker: Francesco Ficara (Istituto Nazionale di Astrofisica (INAF))

Ficara WST.pdf

24 Unveiling the Secrets of Ultra-Faint Dwarf Galaxies with WST

The upcoming Legacy Survey of Space and Time (LSST) that will be conducted by the Vera Rubin Observatory (VRO) promises to boost the number of new ultra-faint dwarf (UFD) galaxies discovered in the Milky Way halo, providing crucial insights into their nature and their role in the evolution of their host galaxies. However, characterizing these elusive systems and unraveling their unique role in the cosmic puzzle requires unprecedented spectroscopic capabilities. The future Wide Spectroscopic Telescope (WST) offers a transformative opportunity to push the boundaries of UFD research. With its characteristics, WST will enable detailed chemical abundance studies and kinematic mapping of UFDs. By bridging the gap between discovery and characterization, WST will illuminate the fossil record of the earliest stages of galaxy formation and provide critical insights into the smallest building blocks of the Universe.

Speaker: Dr Massimiliano Gatto (Istituto Nazionale di Astrofisica (INAF))

Gatto.pdf

12:55 Lunch

The Local Universe

25 A chemical close-up of the Local Group galaxies

The Local Universe offers a unique window into the process of hierarchical mass assembly across all scales. In particular, the Local Group provides an exceptional opportunity to study different types of galaxies in detail, for instance gas-rich, interacting galaxies and gas-poor, isolated systems.
Investigating the chemical composition of stars in galaxies with diverse star formation and chemical enrichment histories is key to understanding the formation and evolution of our Local Universe.
In this talk, I will review the current state of knowledge on the chemical composition of the smallest galaxies in the Local Group, highlighting the key questions that the future advent of WST will help address.

Speaker: Alessio Mucciarelli (DIFA - University of Bologna)

Mucciarelli.pdf

26 The galaxy matter cycle as seen by WST

The evolution of galaxies is driven by feedback processes occurring on small scales, galaxy-scale dynamical processes, and the interplay between galaxies, their dark matter haloes, and the intergalactic medium. Understanding the flows of matter and energy across these different scales is key to improving our understanding of galaxy evolution. Large surveys of galaxies provide sufficient statistics to study the link between galaxies and their halos, and the large-scale structure.Addressing the interstellar medium (ISM) matter cycle and the physics of star formation, on the other hand, requires a statistical perspective at a resolution comparable with the size and separation length characteristic of star-forming regions. In this contribution I will discuss the contribution WST can make the study of the cycle of matter in nearby galaxies, within the wider context of the WST extragalactic science case.

Speaker: Francesco Belfiore (Istituto Nazionale di Astrofisica (INAF))

Belfiore.pdf

27 Understanding the origin of present-day galaxy Hubble types in different environments

The variety of galaxy types that we observe today originates from different physical mechanisms, each producing distinct features in the spatially resolved star formation history and stellar kinematics. We propose to use the IFS@WST to carry out a systematic, spatially resolved study of the galaxy population in the nearby (z~0.07) and intermediate-z (~0.3) Universe, targeting ~ 1000 systems in different environments. The resulting dataset will provide an unprecedented view on on the assembly history and formation channels of the different galaxy types in the latest cosmic epoch

Speaker: Antonino Marasco (Istituto Nazionale di Astrofisica (INAF))

Marasco_WST.pdf

28 Probing the limits of spectroscopy in the low-surface brightness Universe with LEWIS

Ultra-diffuse galaxies (UDGs) are extremely faint $(\mu_{0,g} \geq 24$ mag/arcsec²) and diffuse $(R_e \geq$ 1.5 kpc) systems whose nature is unknown. Literature is now plenty of imaging data on UDGs whereas spectroscopic follow-up of large samples of UDGs remains rare. The “Looking into the faintEst WIth MUSE” (LEWIS) project will make a decisive impact on the field since it will study for the first time the stellar kinematics, stellar populations and globular clusters properties of a nearly complete sample of 30 UDGs in the Hydra I cluster of galaxies. In this talk, I will present recent results we obtained with LEWIS data, testing the MUSE’s performance under extreme conditions and setting its capabilities and limitations of doing spectroscopy in the low-surface brightness regime. I will show how the upcoming state-of-the-art facilities such as the Wide Space Telescope can open a new perspective on future studies of UDGs.

Speaker: Chiara Buttitta (Istituto Nazionale di Astrofisica (INAF))

UDGs_WST_talk_Buttitta.pdf

29 Spectroscopic analysis of novel HI detections

The upcoming surveys of the SKA will completely change our view of the distribution of atomic neutral hydrogen (HI) in galaxies and their environment. Out to z~1, SKA will provide HI masses of half a million galaxies, spanning from gas-rich low-surface brightness sources to massive early type sources and Active Galactic Nuclei. Most of these sources will not have spectroscopic information, thus leaving an incomplete characterisation of the ISM and stellar properties of these galaxies. In this talk, I will show how the WST because of its wide field of view and high spectral resolution will enable us to properly characterise the novel SKA-HI sources and also investigate the properties of the gas-poor (HI-non detections) living in the same environments.

Speaker: Filippo Maccagni (Istituto Nazionale di Astrofisica (INAF))

20250311-WST_maccagni.pdf

15:50 Coffee Break

Galaxy assembly and evolution

30 Galaxy assembly and the cosmic web

The cosmic web, in its many facets, is known to shape galaxy
evolution. It is a fundamental task to understand how and when the
various components of the cosmic web, still in formation, began to
affect galaxies' life. WST capabilities will be crucial in shading
light in this context. I will briefly review some of the open
questions related to the many component of the cosmic web, and the
role of WST in addressing them.

Speaker: Olga Cucciati (Istituto Nazionale di Astrofisica (INAF))

31 Probing the distribution and nature of DM of tens of millions of galaxies: more and better than before

Ongoing and upcoming wide-field imaging campaigns, such as the Euclid Wide and Deep Surveys and Rubin Observatory’s LSST, will enable measurements of the photometric and structural properties of tens of millions of galaxies, spanning the local Universe to redshifts of 2–3 and beyond, from dwarfs to the most massive galaxies. In particular, Euclid will uncover hundreds of thousands of dwarf galaxies in the local Universe and over 100,000 galaxy-scale gravitational lenses. However, only a small fraction of these objects will be targeted by upcoming spectroscopic facilities like 4MOST and WEAVE.

The WST positions itself as a unique facility for the comprehensive spectroscopic follow-up of these galaxies. A dedicated survey to measure velocity dispersions and thereby total masses for tens of millions of galaxies, utilizing the different WST observing modes (MOS-LR for large statistical samples, MOS-HR for low velocity dispersion galaxies, and IFS for specific targets), will have transformative scientific outcomes. These include:

a) providing the characterization of dark matter content as a function of galaxy mass and redshift for unprecedented numbers of galaxies;
b) constraining dark matter in the central regions of newly discovered dwarf galaxies in the local Universe, offering critical insights into the nature of dark matter; and
c) spectroscopic validation and velocity dispersion of ~100,000 galaxy-galaxy strong lenses, yielding key information that, combined with strong lensing constraints, will enable the most precise constraints on galaxy dark matter fractions and mass profiles across redshifts, masses, and galaxy types.

The WST can thus create the most comprehensive atlas of galaxies with constraints on their dark matter content in the southern hemisphere.

Speaker: Crescenzo Tortora (Istituto Nazionale di Astrofisica (INAF))

WST_Napoli_2025_Tortora_x_pdf.pdf

32 Environment effects on galaxy evolution with WST: insights from the COSMOS Wall

We present a potential science case for the WST facility, focusing on the detailed characterisation of galaxy stellar populations as a function of the environment. This builds on the analysis we performed on a restricted sample of massive quiescent galaxies in the COSMOS Wall structure at z = 0.73. This structure encompasses a diverse range of environments, from rich and dense clusters to field-like regions, providing a comprehensive laboratory to investigate the interplay between galaxy properties and the environment.
By leveraging spectroscopic data from the LEGA-C survey and photometric data from COSMOS2020 catalog, we used an innovative full-index and photometric joint fitting approach to derive precise stellar population parameters of the Wall galaxies, such as mass-weighted ages, metallicities, and star formation timescales. Our findings from the COSMOS Wall suggest that galaxies in denser environments are more than 1 Gyr older and exhibit shorter star formation timescales compared to their field counterparts, underscoring the role of large-scale structure in the quenching process of galaxies already at z ~ 0.73.
WST will revolutionise the study of galaxy evolution driven by environmental effects at intermediate redshifts. Indeed, WST exceptional multiplexing capability will allow the analysis of thousands of galaxies in each environment—a substantial improvement on available studies— allowing to sample the galaxy population until z ~ 1 and down to log(M/Msol) ~ 9.5, offering unprecedented insights into their stellar populations and baryonic cycle.
Moreover, the wide spectral range covered by WST, unlike the more limited range of current intermediate redshift surveys (e.g. LEGA-C), will enable the access to crucial absorption lines, significantly reducing degeneracies and allowing a more precise characterisation of the stellar population properties, including different chemical compositions, of these galaxies.

Speaker: Fabio Rosario Ditrani (Istituto Nazionale di Astrofisica (INAF))

Napoli_WST_Ditrani.pdf

33 Unveiling the cosmic web through Lyα emission: from MUSE to WST

The existence of filaments connecting galaxies, within which galaxies form, has been a long-standing prediction of structure formation theories in a Universe dominated by cold dark matter. However, direct imaging of these filaments has remained elusive until the advent of large-format integral field spectrographs such as the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope.
In this talk, I will present recent direct detections of cosmic web filaments in Ly$\alpha$ emission from an ultradeep (142-hour) observation in the MUSE Ultra Deep Field. This trasformational dataset enables us to directly study the physical properties —including morphology, surface brightness profiles, and the transition radius between the circumgalactic medium and the intergalactic medium— of at least two extended emitting structures. These filaments span scales ranging from $\sim 3$ cMpc to $\sim 5$ cMpc and are observed both between two massive nodes of the cosmic web (a pair of bright quasars at redshift $z\sim3.22$) and within a rich overdensity of Lyα emitters at redshift $z\sim4$.
I will compare these observations to predictions from numerical simulations.
These exciting discoveries mark a significant step forward in studying large-scale structures in emission, offering a powerful new way to trace the distribution of dark matter and gas dynamics in the cosmic web.
Looking ahead, I will discuss the key role of the Wide-Field Telescope (WST) in detecting and characterizing cosmic web filaments in Lyα emission. Its unmatched field of view and sensitivity will enable us to build statistical samples of filaments across diverse environments, paving the way for breakthroughs in our understanding of the physical processes shaping the large-scale Universe and governing gas accretion within these structures.

Speaker: Davide Tornotti (Università degli Studi Milano-Bicocca)

Napoli_2025_Tornotti_short.pdf

Multi-messenger Astrophysics: the landscape and synergies

34 Transients and multi messenger astrophysics (and synergy with ACME project)

Speaker: Paolo D'Avanzo (Istituto Nazionale di Astrofisica (INAF))

WST_workshop_20250311_ACME_davanzo.pdf

35 The great synergy between WST and THESEUS

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large European collaboration under study by ESA since2018 and currently one of the three candidate M7 mission for a launch in mid '30s. THESEUS aims at fully exploiting Gamma-Ray Bursts for investigating the early Universe and as key phenomena for multi-messenger astrophysics. In particlar, By providing an unprecedented combination ofX-/gamma-ray monitors, on-board IR telescope and spacecraft autonomous fast slewing capabilities,THESEUS will be a wonderful machine for the detection, multi-wavelength characterization and redshift measurement of any kind of GRBs and many classes of X-ray transients, including high-redshift GRBs for cosmology (pop-III stars, cosmic reionization, SFR and metallicity evolution up to the “cosmic dawn”) and electromagnetic counterparts to sources of gravitational waves. THESEUS will also provide breakthrough measurements of GRB prompt and afterglow emission, as well as the detection and multi-eavelength characterization of many classes of high-energy transients. In all these respects, THESEUS will thus provide an ideal synergy with the very large astronomical facilities of the future working in the e.m.and multi-messenger domains. In particular, the sinergy between THESEUS and WST would be outstanding, substantially enhancing the scientific return of these two great facilities in their core science objectives in cosmology, multi-messenger and time-domain astrophysics.

Speaker: Lorenzo Amati (INAF .- IASF Bologna)

Amati.pdf

19:00 Bus

20:00 Social Dinner

Wednesday 12 March

Multi-messenger Astrophysics: the landscape and synergies

36 Einstein Telescope: the next generation European Gravitational Wave observatory

The current generation of gravitational wave (GW) detectors, Advanced Virgo and Advanced LIGO, have opened a new window on the Universe by detecting GW signals in the Hz-kHz frequency range. Monumental scientific goals have been achieved thanks to their observations.

A new generation of terrestrial and space-based interferometric GW observatories is being prepared to replace the current generation of GW detectors in the next decade. This will make it possible to search almost the entire Universe for GW signals. Einstein Telescope (ET) is leading the design, preparation and implementation of next-generation terrestrial GW observatory in Europe. ET aims to detect all stellar or intermediate-mass black hole mergers throughout the Universe, testing general relativity in the presence of a strong gravitational field. ET will detect a large fraction of the coalescences of binary neutron star systems in the Universe, shedding light on the equation of state that governs the physics of these compact bodies. ET will contribute to the understanding of dark matter and dark energy by looking at the gravitational side of this puzzle.

An overview of the scientific objectives, the observatory design, the required technologies and the project organisation of Einstein Telescope is presented.

Speaker: Michele Punturo

Punturo.prn

37 WST and Gravitational Waves: Exploring the Era of Next-Generation Ground-Based Observatories

The detection of the first gravitational-wave signal from the merger of a binary neutron star system, GW170817, together with its optical counterpart AT2017gfo, provided firm evidence that such mergers produce kilonovae and are crucial for heavy element formation in the Universe. While GW170817 demonstrated the vast potential of multi-messenger astronomy, impacting fields from relativistic astrophysics to cosmology and nuclear physics, it remains a rare event. Next-generation gravitational wave observatories, such as Einstein Telescope (ET) and Cosmic Explorer, will dramatically increase detection rates, identifying up to 10^5 binary neutron star (BNS) mergers per year and extending our observational horizon far beyond the peak of star formation. This talk will explore the revolutionary multi-messenger prospects for the next-generation observatories. Starting from the expected optical signals from the BNS merger populations, we will discuss the prospect of optical counterpart detections using wide-field optical telescopes, highlighting the unique synergy with WST.

Speaker: Marica Branchesi (Istituto Nazionale di Astrofisica (INAF))

WST_Napoli_Mbranchesi.pdf

38 WST-ET synergy for next generation gravitational wave multi-messenger observations

With next generation gravitational wave interferometers such as the Einstein Telescope (ET) and Cosmic Explorer (CE) it will be possible to explore a larger volume of the Universe with respect to now, detecting up to 10$^{5}$ binary neutron star system mergers (BNS) per year beyond the Local Universe. The optical-NIR EM counterparts of such GW signals will be faint and will have to be found within vast regions of the sky, among a huge number of contaminants. Spectroscopy, the only secure tool to identify and characterise EM counterparts, will become the bottleneck of GW MM science. In this framework, Integral Field and Multi-Object Spectroscopy (IFS and MOS) with an ambitious next generation facility such as WST, will play a key role in the game of identifying and characterizing counterparts.
I will present the results of the simulations I carried out within the WST Time Domain working group and the MM Division of the ET Observational Science Board, to assess the impact of WST IFS and MOS on next generation GW-MM observations. I will outline the observing strategies that can be adopted with WST and show the key role of WST in answering the observational challenges of MM observations of next-generation GW interferometers.

Speaker: Sofia Bisero

Cosmology and fundamental physics

39 The promise of WST for Cosmology

Understanding the nature of cosmic acceleration and dark energy remains one of the most profound challenges in modern cosmology. To address these mysteries, upcoming large-scale spectroscopic surveys aim to map the three-dimensional distribution of millions of galaxies across vast cosmic volumes and look-back times. As the most powerful next-generation spectroscopic facility, the Wide-field Spectroscopic Telescope (WST) will revolutionize cosmology by dramatically increasing the number of measured galaxy redshifts. WST will probe the growth of structure and cosmic expansion history through redshift-space distortions and baryon acoustic oscillations, while also testing models of inflation by detecting non-Gaussianity on the largest scales. The primary WST legacy survey will target galaxy tracers up to redshift 𝑧$∼$1.6, where dark energy effects become prominent. Additionally, higher-redshift surveys will push measurements of cosmic expansion and structure growth to 2$<$z$<$5, with extensions to z$∼$7 via Lyman-alpha emitters. Beyond its role in tracing cosmic evolution, WST will enable precise constraints on neutrino mass, improve limits on non-Gaussianity by an order of magnitude over current experiments, and refine our understanding of multi-field inflation scenarios. Moreover, its capabilities will support complementary studies, including Lyman-alpha forest correlations to probe dark matter properties, intrinsic galaxy alignments for weak lensing corrections, and spectroscopic follow-up of gravitational wave and fast radio burst sources to enhance cosmological distance measurements. With its unprecedented combination of survey depth, spectral resolution, and versatility, WST stands poised to transform our understanding of the cosmos.

Speakers: Dr Carmelita Carbone (INAF IASF-MI), Michele Moresco

WSTItalia_Cosmology_Moresco.pdf

40 Type II Cepheids as an alternative route to the Hubble constant

Type II Cepheids are useful distance indicators and stellar tracers for old stellar populations. For instance, they have been used to find the distances of the Magellanic Clouds and to measure their tridimensional geometry.
Rubin LSST will allow us to detect and characterize Type II Cepheids in the Local Group galaxies and beyond. In particular, we have verified that the Rubin LSST observations will allow us to observe and correctly characterize Type II Cepheids up to a few Mpc. This will enable us to use them as alternative calibrators of the cosmic distance scale. To this aim, we will adopt locally calibrated period-luminosity-metallicity relations which require both photometry and spectroscopically-based abundances. While optical photometry can be provided by Ruvin LSST and the Near Infra-red by space missions like Euclid/Roman, WST with its sensitivity and multiplexing capabilities, will be the only instrument capable of providing the metallicity information. This, in turn, will make type II Cepheids valid alternative standard candles for the extragalactic distance scale.

Speaker: Teresa Sicignano (ESO)

wst_sicignano_2025.pdf

41 Cosmology with cosmic voids

Cosmic voids, the underdense regions of the universe, offer a unique opportunity for understanding the cosmos. These mildly nonlinear structures preserve the evolutionary imprints of the universe, making them invaluable for constraining cosmological parameters and exploring new physics, that can be unlocked using the potential of WST. In this talk, we present the current status of the void-galaxy cross-correlation function, emphasizing its capability to extract cosmological constraints, and highlighting the constraints achievable through combining it with other void statistics, e.g., the void size function.

Speaker: Giulia Degni (Università Roma Tre)

WSTVoids_GiuliaDegni.pdf

42 Gravitational Wave Cosmology in the age of wide-field spectroscopic surveys

Gravitational waves (GWs) from compact binary coalescences provide direct luminosity distance measurements, making them ideal "standard sirens". However, to be used as cosmological probes information on source redshifts has to be included with priors on the astrophysical populations and external electromagnetic data. In a recent analysis of LIGO-Virgo-KAGRA O4 and O5 scenarios, we demonstrate the critical importance of spectroscopic surveys to maximize the scientific return of standard sirens (Borghi et al. 2024). In particular, we find that O5 best 100 binary black holes could enable a percent-level $H_0$ measurement with a complete spectroscopic galaxy catalog. The precision drops by a factor of ~10 with photometric data, requiring more careful modeling of the astrophysical population to avoid bias. Notably, the O4 configuration with spectroscopic data outperforms O5 with photometric data for $H_0$ constraints. To address the methodological and computational challenges of future surveys, we release CHIMERA, a hierarchical Bayesian pipeline enabling joint cosmological and astrophysical population parameter constraints. This novel framework represents a significant step forward in preparing for wide-field spectroscopic surveys, such as WST, which could play a key role in the future of gravitational-wave cosmology.

Speaker: Nicola Borghi (University of Bologna / National Institute of Astrophysics (INAF))

Borghi_WST25.pdf

43 Cosmology with higher-order statistics with the Wide Field Spectroscopic Telescope

Higher-order statistics in galaxy clustering constrain non-Gaussian information, offering a pathway to more precise measurements of the statistical properties of the Universe on large scales. This is particularly relevant for probing dark energy, dark matter and phenomena associated with nonlinear evolution, the effects of massive neutrinos, and primordial non-Gaussianity. In this talk, I will discuss how the Wide Field Spectroscopic Telescope provides a unique opportunity to constrain the large-scale properties of the Universe at high redshift, enabling new insights into its underlying physical processes.

Speaker: Massimo Guidi (University of Bologna)

Guidi - WST - Napoli - 12nd March 2025.pdf

44 Back-in-time Void Finder: dynamical void finding for new generation Cosmology

WST will push the boundaries of our understanding of the Universe, providing an unprecedented amount of data from regions previously unreachable by any observational survey. Next-generation datasets will require a new suite of models and tools designed for the next level of precision cosmology: cosmic void studies are no exception.
I present a novel dynamical void-finding algorithm, the Back-in-time Void Finder, specifically developed for precision cosmology. This method reconstructs the tracer velocity field to identify cosmic voids as the points of maximum divergence in the displacement field, effectively pinpointing regions from which the largest mass outflows originate. Optimized for large-scale surveys, the algorithm produces catalogues of pure voids, tailored for various cosmological applications such as the void-galaxy cross-correlation function, void size function, and velocity profile analyses.

Speaker: Simone Sartori (CPPM/CNRS)

SimoneSartoriWST.pdf

45 The WST view of the TDE population

An unfortunate star passing too close to a Super Massive Black Hole (SMBH) can be destroyed by the strong tidal forces at play, giving rise to a Tidal Disruption Event (TDE). These transient phenomena manifest themselves as a luminous, short-lived, UV/optical/Xray flares coming from the nuclei of otherwise quiescent galaxies and have been heralded as a unique laboratory for studying SMBHs. TDEs reveal the presence of dormant low-mass SMBHs and they can unveil intermediate mass black holes (IMBH) in the local universe. They are powerful tool to study accretion-related phenomena on human-friendly time scales few months at all wavelengths and they can be used to probe the SMBH occupation fraction in different types of galaxies. Their rate and its evolution over cosmic time can give important information on the existence of SMBHs at high redshift (z>7). Finally, TDEs are exquisite multi-messenger phenomena, being candidate sources of high-energy neutrinos and gravitational wave (GW) sources potentially detectable by the future space-based interferometers such as LISA and the LGWA.

In the last decade, thanks to the availability of increasingly efficient wide-field optical surveys, the sample of TDEs has rapidly grown from a few candidates to tens of confirmed TDEs. The optical band has become the primary discovery channel and it became clear that the most important physics is encoded in the TDE spectra. A heterogeneous population of transients have been thus revealed, with some well established key observational features but also characterized by a broad range of properties, with each event still providing new clues but raising new questions. Indeed it is still a puzzle how TDE prompt emission is produced as well as the properties of the emission region itself, with many scenarios being proposed so far, but still under debate.

We are now in a TDE golden age, with a discovering rate reaching ∼10/yr thanks to the ZTF survey. However, the upcoming advent of the Vera Rubin Observatory Legacy Survey of Space and Time (VRO-LSST) will greatly increase the TDEs discovery rate up to ∼1000/yr, bringing TDE science into a new era. A WST spectroscopic survey would thus be transformational both for TDE and for SMBH physics.

I will present the new results from multi-wavelength follow-up campaigns performed with high quality photometric and spectroscopic observations, which have allowed to deeply investigate on the TDE spectroscopic features and their evolution with time. The implication on the underlying UV/Optical emission mechanism and on the properties of the emitting region will be discussed together with the invaluable impact that a WST survey targeting TDEs will have.

Speaker: Francesca Onori (Istituto Nazionale di Astrofisica (INAF))

Onori.pdf

46 WST survey of fundamental constant variations

Some theoretical extensions of standard cosmology predict that values of fundamental constants vary in time and/or in space. The analysis of 300 quasar absorption spectra collected with VLT/UVES and Keck/HIRES indicate that the fine structure constant, $\alpha$, may vary as a dipole across the sky. These results are currently being followed-up through observations made using extremely precise spectrographs such as VLT/ESPRESSO, which will produce ~100 measurements by 2040.

The WST offers the possibility to produce several thousand measurements in only a few years. The large collecting area, high spectral resolution, and the large multiplexing of WST would be particularly suited to conducting a dedicated survey of varying constants, mapping out any potential variation as a function of time and direction, and placing constraints on fundamental physics theories. I will discuss the requirements such a project would impose on WST.

Speaker: Dinko Milakovic (Istituto Nazionale di Astrofisica (INAF))

2025-03-12-MILAKOVIC_WST_fundamental_constants.pdf

11:10 Coffee Break

Synergies, lesson learned, and challenges

47 The ESO ELT - progress update

Speaker: Joel Vernet

JVernet.pdf

48 WEAVE and 4MOST: the lessons we (can) learn

The spectrographs WEAVE and 4MOST, both on 4m class telescopes, are two predecessors to the innovative WST facility.   
Both spectrographs are characterized by high multiplexing capabilities over a large field of view (i.e., 3-4 sq. deg), wide optical spectral coverage (3700 - 9700 Å), and optimal resolution (R=4000-7000). StePS is the acronym for two surveys that make use of the WEAVE and 4MOST instruments to study the properties of stellar populations of massive galaxies at intermediate redshifts (i.e., 0.3 < z < 0.7–0.8), where the instrumental spectral window covers all the usual optical features and the beginning of the UV range.  

The larger collecting area of WST (12 m) will offer a unique opportunity to extend these studies to higher redshifts. At redshifts above 1, the Universe and the galaxies within it become increasingly younger, while the observed spectral window shifts to cover the UV range (λ < 4000 Å) and the optical range moves beyond reach.

In this talk, we will explore the potential of utilizing the UV range to study the stellar population properties of galaxies at high redshift. Through simulations, we will compare the effectiveness of UV-based indicators in deriving the properties of young galaxy populations with the results obtained using the optical range. Furthermore, the critical limitations of current models in accurately representing this range will be highlighted and discussed.

We will finally discuss how the WEAVE-StePS and 4MOST-StePS surveys will enable the 'calibration' of the UV range in terms of galaxy evolution studies.

Speaker: Marcella Longhetti (Istituto Nazionale di Astrofisica (INAF))

LonghettiM_WSTmeeting_2025.pdf

49 The Big Data Challenges of WST in the 2040's

The Wide-Field Spectroscopic Telescope (WST) will revolutionize astronomical spectroscopy in the 2040s by generating an unprecedented volume of data for the field: tens of thousands to millions of spectra hourly ($\sim$1 TB/night of raw science data).
While the raw data rate per se is modest compared to other facilities (like SKA), the complexity of spectroscopic data processing presents unique challenges for automated analysis and scientific discovery, particularly in balancing automation with necessary human oversight.
This talk addresses four critical aspects of the WST data pipeline:
1. automated data reduction optimization incorporating machine learning for quality assessment and anomaly detection;
2. low-latency processing capabilities essential for time-critical observations and dynamic survey optimization;
3. development of intuitive visualization tools for rapid human validation of complex spectroscopic products; and
4. generation of advanced science products using computationally intensive methods (possibly to be implemented in a distributed computing network) for feature extraction, classification, and parameter estimation.
Throughout these components, we stress the importance of engineering flexible yet effective mechanisms for human intervention in an otherwise automated system.

Speaker: Dr Stefano Zibetti (Istituto Nazionale di Astrofisica (INAF))

Zibetti_BigDataChallengeWST_Napoli2025.pdf

50 AI for astronomical spectroscopy: current challenges and future prospects for the WST

WST will deliver datasets of such staggering volume and complexity that conventional analysis methods will be rendered obsolete.
Much faster, precise and independent of our models, artificial intelligence emerges as the indispensable engine of discovery.

The current landscape of machine learning in astronomy, particularly in spectroscopic analysis, faces two critical limitations. The first concerns interpretability: while neural networks demonstrate superior speed and precision compared to traditional methods, their 'black box' nature obscures the reasoning behind their predictions. The second limitation involves uncertainty quantification: current implementations typically fail to provide reliable errors. To overcome these challenges, I will present OssicoNN, a conditional Invertible Neural Network (cINN), through two concrete applications. First, using the Gaia-ESO Survey dataset, I will demonstrate OssicoNN's capability to derive stellar parameters with well-characterized uncertainties. Second, applying OssicoNN to simulated SDSS spectra, I will show how this approach exceeds the accuracy of classical Bayesian methods while providing insights into the features driving the network's decisions.

In the final section, I will outline two pillars of AI-driven astronomy by 2040: foundation models and autonomous agents. Foundation models trained on vast astronomical datasets will act as discovery engines. These models will directly cross-match WST’s data with multi-wavelength surveys, creating unified frameworks to test theories. Second, autonomous agents will execute real-time decision-making: adjusting WST’s focal plane to prioritize transient events, optimizing survey strategies, and coordinating follow-ups with other facilities.

Speaker: Nils G. F. D. Candebat (Istituto Nazionale di Astrofisica (INAF))

Nils Candebat.pdf

51 Classify and Modeling the optical spectrum via neural network

We developed a novel generated neural network to reconstruct the rest-frame spectra by giving the observed spectra and their flux error. This network provided all the necessary information for modeling spectra, including the eigenspectra and coefficient. Using this reconstruction, we can achieve the classifying, redshift estimation, and anomaly detection in the same framework. Our test demonstrates we reach the same level of accuracy in spectral fitting and redshift estimation as the classical method, with at least O(10^(-3)) faster. Combining our previous work (GaSNet-II), which used sub-network assembly, we can achieve error estimation and subclassify for future spectroscopy survey (for 4MOST) pipelines. Those series of deep-learning tools will be implemented in the 4MOST classification pipeline.

Speaker: Fucheng Zhong (Istituto Nazionale di Astrofisica (INAF))

Fucheng_Zhong_WST_GaSNet.pdf

52 New enabling (disrupting) technologies

Speaker: Jacopo Farinato (Istituto Nazionale di Astrofisica (INAF))

Farinato.pdf

13:15 Lunch

Discussion

Conveners: Adriano Fontana (Istituto Nazionale di Astrofisica (INAF)), Andrea Bianco (Istituto Nazionale di Astrofisica (INAF)), Luca Pasquini (ESO), Marcella Marconi (Istituto Nazionale di Astrofisica (INAF)), Marica Branchesi (Istituto Nazionale di Astrofisica (INAF)), Michele Moresco (University of Bologna - Department of Physics and Astronomy), Roberto Ragazzoni (Istituto Nazionale di Astrofisica (INAF))