Abstract Book
In this page you can find all the submitted abstracts to the conferences, alphabetically sorted with a first section on posters and after a section on talks.
Posters
Title: Product Design for Scientific Literacy: development of a multifunctional orrery for cognitive stimulation
Author: F. Alves
Abstract: The impact of scientific and technological advancements on society often depends not only on their inherent relevance but also on the public's trust in science and their ability to understand and apply the associated key concepts. Individuals with Intellectual Disability (ID) are full citizens with equal rights in society. However, the importance of basic scientific and technological literacy is often overlooked in this population, resulting in significant challenges in understanding and predicting the physical world around them. The construction of mental models to interpret fundamental phenomena, such as the cycles of days, seasons, and phases of the moon, is typically underdeveloped in both children and adults with ID. These difficulties are partly associated with a lack of adequate cognitive stimulation, and not solely a result of their impaired abstract reasoning abilities. In many cases, these individuals can understand and apply scientific and technological concepts if they are conveyed appropriately. Most products currently available for cognitive and physical stimulation are either not designed for adults or are not tailored to the intellectual and motor limitations of this user group. Our approach aims to achieve two complementary objectives: a) to promote an intuitive understanding of fundamental astronomy and mechanical concepts; and b) to offer broader cognitive, motor, and sensory stimulation through a variety of activities and product configurations. We developed a simplified mechanical model of the sun-earth-moon system —an orrery— specifically designed for adults with mild to moderate intellectual disability. The product consists of a wooden puzzle composed by a set of interlocking gears of different sizes. Once assembled, it simulates the earth's rotation, as well as the orbits of the earth around the sun and the moon around the earth. Additional components include a ruler that holds the axes supporting the gear mechanism and a circular base representing the four seasons of the year. This project is currently in its initial design phase, with the manufacture of the first functional models. An optimization algorithm was developed to calculate appropriate gear ratios and axes distances under different design requirements and constraints, enabling efficient iteration of alternative configurations and complexity levels. The presented prototype was calculated to simulate the movements of the earth and moon using fewer than 20 large pieces rotating on four axes. The main components were designed in AutoCAD and fabricated from plywood and MDF using a laser cutter. Manual post-processing steps, including sanding, painting, and waxing, were then applied. Additional pieces were crafted from pine wood and manually processed. While this product is specifically designed for adults with mild to moderate intellectual disabilities, the concept can be easily adapted to other types of users. Living with Intellectual Disability poses many personal challenges, from significant limitations in performing intellectual activities to impaired conceptual, social or practical skills needed for everyday life. Our product addresses the supporting foundations of these skills, such as the ability to relate cause and effect, logical thinking, spatial reasoning, problem solving, and hand-eye coordination. This small key intervention builds on highly transferable skills and aims to help users feel more integrated into the world around them. Most individuals with ID continue to develop their abilities, learning and improving skills throughout their lives. Access to tools that support this process contributes to a greater level of independence and social integration and an improved quality of life. The fact that an intricate mechanism with non-intuitive behaviour can be assembled as a puzzle with fewer than 20 pieces inspires curiosity and a sense of accomplishment, and encourages a more confident approach to other seemingly complicated challenges. Keywords Scientific literacy, product design, intellectual disability, cognitive stimulation, inclusion
Title: Re-evaluation of the AGN unification model
Author: S. Amarantidis
Abstract: A long-standing challenge in the field of extra-galactic astronomy revolves around the complexities associated with the emission produced by Active Galactic Nuclei (AGN) and the underlying physics governing Super-Massive Black Holes (SMBHs). At radio frequencies, AGN can manifest as radio galaxies, displaying high values of luminosity at both GHz and MHz frequencies, often accompanied by the presence of radio jets. These jets are defined by their predominant emission, stemming from the sub-Eddington accretion onto SMBHs, a phenomenon often denoted as 'radio' mode accretion. The results presented here are based on the non-trivial realization that the optical, UV and X-ray emission of an AGN correspond to the ongoing accretion disk and its associated rate, while the radio jet might originate from a past AGN phase. This becomes more evident when one considers extensive radio jets, observed in powerful radio galaxies (such as the ones considered in this work), often extending out to tens of kpc. In this poster, I will present the impact of the aforementioned effect on the AGn unification scheme correlating optical/radio AGN characteristics and fundamental properties of SMBH accretion disks.
Title: Modeling the Sun's radial velocity with SOAP using SDO observations: comparison with HELIOS radial velocity data.
Author: A. Barka
Abstract: Exoplanet research has rapidly expanded since the first detection in 1995, with over 5000 confirmed exoplanets. A key focus is finding rocky planets in the habitable zones of solar-type stars. High-resolution spectroscopy is crucial for obtaining precise radial velocities (RVs) to detect these planets. However, stellar contamination from spots and faculae can obscure or mimic planetary signals, complicating their detection. From SDO (Solar Dynamic Observatory) observations, we identify and characterize spots and faculae on the solar disk. Using SOAP (Spot Oscillation And Planet), we simulate their impact on the RV signal both separately and together, and compare the results with solar disk-integrated RV data from HELIOS (HARPS Experiment for Light Integrated Over the Sun). The residuals between observed and simulated data are around 1 m/s. In the future, we aim to enhance these results by improving SOAP and including solar observations from the Paranal solar Espresso Telescope (PoET). These advancements aim to better understand and mitigate the effects of stellar activity on RV measurements, ultimately aiding in the more accurate detection of exoplanets in the habitable zones of solar-type stars.
Title: Exploring the Radio Properties of AGN using the Million Quasar Catalogue
Author: L. Barroso
Abstract: Highly luminous Active Galactic Nuclei, including Quasars, are believed to be powered by accretion onto supermassive black holes. Emitting energy across the electromagnetic spectrum, including visible light, radio waves, and x-rays, these are among the brightest objects in the universe and provide insights into the AGN phenomena, its key role in galaxy formation and evolution, and the early universe. In particular, galaxy growth appears to be closely linked to SMBH growth, which happens via different accretion modes: quasar mode, corresponding to a high accretion rate and generating strong optical and X-ray emission, radio mode, typical of slower accretion rates and typically producing outflows of material that are bright at radio wavelengths, and a merger mode, where SMBH growth takes place upon the merger of two galaxies and their SMBHs. Over the last decades, powerful AGN have been mostly traced using optical and near-infrared observations (e.g., the large SDSS quasar catalogue, identifying over 500000 quasars), or X-ray observations, which offer us only a partial view of the accretion phenomena. Radio selection of AGN has only recently witnessed a renewed interest, as new methods of reaching the highest redshifts have been developed, and the perspective of the direct study of the neutral Hydrogen at the Epoch of Reionization by the upcoming Square Kilometre Array (SKA) prompts for a deeper knowledge of the radio AGN population. With the goal of characterising the radio properties of AGN at all redshifts, we have explored the radio properties of the Million Quasar Catalogue, one of the largest catalogue of powerful AGN available. By considering three of the deepest large area radio surveys available (the LOFAR Two-metre Sky Survey, LoTSS, at 150 MHz; the Rapid ASKAP Continuum Survey, RACS, at 888 MHz; and the VLA Sky Survey, VLASS, at 3 GHz) we characterise the radio luminosity and radio spectral index of these powerful AGN out to z~7. For a subset of these sources we correlate the radio properties with optical and near-infrared characteristics, in order to identify differences between the so-called radio-powerful and radio-weak AGN population. By using the resulting dataset, we are now aiming to develop a better understanding of the radio emission from powerful AGN and optimise the AGN selection for the next-generation radio surveys with the so-called SKA-pathfinders (namely ASKAP and MeerKAT, where an active participation of our team exists) and, in the future, for the SKA itself.
Title: OLHANDO O FIRMAMENTO: A OBSERVAÇÃO ASTRONÓMICA NO ATUAL TERRITÓRIO PORTUGUÊS DURANTE O NEOLÍTICO
Author: T. Canhota
Abstract: A observação da esfera celeste foi uma das mais antigas atividades “científicas” da Humanidade, contribuindo de forma indelével para o estabelecimento das primeiras civilizações. Num mundo marcado pela penumbra noturna, apenas clareada pelo luar ou pelas labaredas das fogueiras, o exame contínuo dos corpos celestes e o registo, oral e intergeracional, da regularidade com que apareciam no firmamento permitiram a construção de padrões célicos. Posteriormente, este saber haveria de dar origem aos primeiros calendários, revelando-se fundamental para o aparecimento e a organização das futuras sociedades agro-pastoris. Deste modo e no atual território português foram identificados os seguintes monumentos megalíticos/observatórios astronómicos: cromeleque do Vale de Maria de Meio, Évora (7000/8000 anos); cromeleque dos Almendres, Évora (5000/6000 anos); cromeleque de Xerez, Reguengos de Monsaraz (5000/6000 anos); cromeleque da Portela de Mogos, Évora (6000/7000 anos) e cromeleque de Cuncos, Montemor-o-Novo (sem datação). Entre os objetivos adstritos à execução do presente trabalho, pretendemos colocar em evidência o património megalítico de cariz astronómico e a sua localização geográfica, contribuindo assim para a preservação e a divulgação da sua memória e importância histórica. Numa altura em que a exploração do Espaço recorre a tecnologia de ponta, convém recordar, socorrendo-nos da História, que num período mediado entre 5000 e 8000 anos, também estes monumentos eram o que de mais avançado existia na auscultação astronómica. Infere-se, pelo exposto, da importância que estes sítios detinham para a comunidade, não apenas para a sua organização temporal, mas igualmente pela sua imponente construção e manutenção durante milénios, revelando-nos uma ou, quiçá, a principal característica da Humanidade: a curiosidade!
Title: CosmoGen: Genetic Algorithm-Based Exploration of Dark Energy Dynamics
Author: D. Castelão
Abstract: We introduce CosmoGen, a computational framework developed in Python, using genetic algorithms (GA) to generate and evaluate cosmological models with varying dark energy components. This framework uses the Differential Evolutionary Algorithm for Search and Optimization (DEAP) library to evolve equations of state and speed of sound for dark energy, evaluating their physical validity through the Boltzmann code CLASS. Our approach provides a new method to explore the vast space of potential dark energy models and identify viable candidates based on their dynamical properties.
Title: The stellar activity in stars with exoplanets
Author: T. Monteiro
Abstract: The characterization of stars is a crucial step for the study of many astrophysics topics, in particular for the characterization of planetary systems. Specifically, the stellar activity is important to understand the environment of exoplanets, the age of planetary systems and their birth environment. This characteristic also interferes with the detection and characterization of exoplanets using either the RV method or transits, as well as in the characterization of exoplanet atmospheres via transmission spectroscopy. Stellar activity is not a static parameter, and it varies in a time scale that we need to understand for each star. In this work, we developed a pipeline to characterize the stellar activity of stars with exoplanets. Many of these stars have a significant amount of spectroscopic data which were taken with the goal of finding exoplanets. This spectral data is spread in a wide time range for several stars and can be used to better characterize the stellar activity. This pipeline’s goal is to complement SWEET-Cat (Santos et al. 2013; Sousa et al. 2021) with this relevant information for the planet-host stars for which we have good spectroscopic data. For this, given a star identifier and the spectrograph name, the pipeline downloads the best spectra from ESO’s data base, corrects them by the radial-velocity (RV) and measures specific activity spectral indices with an already implemented tool (https://github.com/gomesdasilva/ACTIN2/). Additionally, the pipeline converts the indices to common literature ones and computes all the relevant statistics, including activity periods through GLS periodograms, chromospheric rotation periods and chromospheric ages, through literature calibrations. New links between the properties of known exoplanets and their host stars’ properties can revolutionize the understanding of exoplanetary systems, being the most well known the metallicity correlation for giant planets. The compiled information about the stellar activity provided by this pipeline can then be used to find correlations between this characteristic and the properties of the planets hosted by these stars.
Title: AstroLingua: expanding inclusivity for extragalactic astronomy outreach
Author: A. Paulino-Afonso
Abstract: Making astronomy accessible to all populations is a goal we should all strive for. With the AstroLingua project, we combine advanced image processing with generative AI to create automated captions for extragalactic astronomical images. We are using the Galaxy Zoo dataset to create the first trained model. We will then use large language models to create more synthetic captions to allow for text diversity. By the end of the project (February 2025) we will make both the model and a public web page where one can interact with the model. We hope that AstroLingua paves the way for a more inclusive outreach and education in astronomy in the Portuguese language.
Title: Towards a comprehensive method for detecting broadband transmission spectra of exoplanets using high-resolution transmission spectroscopy
Author: M. Sousa
Abstract: The characterization of exoplanet atmospheres has significantly advanced since the first atmospheric detection in 2002. High-resolution spectroscopy (HRS) during transits has been crucial for understanding their atmospheric composition, structure, and dynamics. Despite these advancements, precise photometric calibration of ground-based spectrographs remains challenging, limiting comprehensive broadband signal characterization. A notable alternative approach is the chromatic Rossiter-McLaughlin (RM) effect, which exploits the fact that an exoplanet with an atmosphere exhibits a wavelength-dependent scale height, impacting the measured radial velocities (RVs). Since the RM effect is highly sensitive to the planet-to-star radius ratio, its chromatic variation with wavelength offers a promising avenue for atmospheric characterization. This technique remains relatively unexplored but has yielded successful results. Building on this, we propose to investigate the chromatic Doppler tomography (Esparza Borges, 2022) approach, which offers potential advantages over chromatic RM by utilizing the full information contained in the residual CCFS. This project aims to enhance and generalize this methodology, integrating it within the automated chromatic fitting algorithm (CaRM). Later we will apply it to ESPRESSO data of HD 209458b and HD 189733b. By doing so, we aim to achieve a more comprehensive understanding of exoplanets' atmospheres.
Title: "A JWST IFU deep study of gas, dust, and PAHs in a prototypical externally illuminated protoplanetary disk"
Author: S. Vicente
Abstract: JWST Cycle2 program GO 4332 (PI: S. Vicente) conducts a deep observational study of an EUV+FUV externally illuminated protoplanetary disk (proplyd) found in the Orion Nebula Cluster (ONC) using the IFU modes of NIRSpec and MIRI-MRS. The JWST IFU observations spatially resolve the disk, neutral cocoon and ionization front simultaneously over the 0.9 - 11.7 micron spectral range providing key line, continuum and PAHs diagnostics to trace the physical conditions, the chemical composition and abundances under the effect of the external FUV-radiation. It is the FUV radiation that changes the thermal structure and chemical composition of the disk and sets the mass-loss rate through photoevaporation. By comparing our results to those of protoplanetary disks (TTauris) found in nearby low-mass star forming regions one can start to assess the real effects of a FUV-dominant environment on protoplanetary disk evolution and planet formation. In this poster I will show preliminary results of the already acquired MIRI-MRS observations.
Title: Quenching Through the Eyes of MOONS
Author: E. Worrell
Abstract: Studies of local galaxies (z ≈ 0.1) using data from the Sloan Digital Sky Survey (SDSS) have shown that galaxies make up two distinct populations- star forming galaxies, appearing in the 'blue cloud', and quiescent galaxies in the 'red sequence'. Between these two populations lies the 'green-valley', a sparsely populated area of galaxies with properties that suggest these galaxies are transitioning from the blue cloud to the red sequence. The lack of galaxies in this region suggests that there exist rapid processes which relentlessly suppress star formation but this quenching is yet to be fully understood. One candidate to contribute to the suppression of star formation is feedback from active galactic nuclei (AGN). High-resolution observations of a statistically significant number of galaxies are crucial to investigate quenching, specifically around the epoch of peak star formation and AGN activity, Cosmic Noon (z~2). The incoming next-generation Multi-Object Optical and Near-Infrared Spectrograph (MOONS) and its extragalactic survey (MOONRISE) will observe up to 500,000 galaxies in the range redshift 0.9 < z < 2.6, filling the existing gap in data. In preparation for MOONRISE, we compiled the existing multi-wavelength studies of AGN selected through a range of criteria (eg. X-ray, radio, mid-infrared selections, SED fitting); for which a comprehensive study of the multiwavelength properties of known and potential AGN sources will be presented with this work. This compilation is a crucial step in the preparation for MOONS observations and will provide a comprehensive source catalogue to guide observations.
Talks
Title: Probing the interior of Subdwarf B stars with asteroseismology
Author: J.H. Amaral
Abstract: Background & Aim: In this work three stars were studied with recourse to asteroseismic techniques: EPIC211779126 [2], KIC 10001893 [4] and KIC10553698A [3]. These are hot pulsating subdwarf-B stars (sdBs). In this type of stars, g modes propagate from the surface to the boundary of the convective core. The use of asteroseismology in sdBs gives the opportunity to test various mixing scenarios near the border of the convective core. When there are sharp variations in the buoyancy frequency inside the g-mode propagation cavity -known as structural glitches- the period spacing, i.e., the difference in the periods of two consecutive modes of the same degree l, deviates from the constant asymptotic value. Glitches are usually associated to strong gradients in chemical composition, resulting from a combination of physical processes. Characterizing the chemical gradients in the cores of sdBs would be very useful to improve the theoretical models. Methods: In this work, it was validated against data collected with the Kepler space telescope, analytical expressions for the reduced period spacing in the presence of structural glitches proposed by Cunha et al. (2019) [1]. Two types of glitches were studied: gaussian glitches and glitches modelled by a step-function. For each star various scenarios were considered, using gaussian glitches and glitches modelled by a stepfunction. A python code was developed using Dynamic Nested Sampling to obtain the best fit model, compare it with the observed data, and to obtain the glitch parameters. Results: For both the stars EPIC 211779126 and KIC10553698A the results show that the scenarios that best describe the observational data are when it is considered one glitch modelled by a step-function and when it is used a gaussian glitch. For the star KIC 10001893, the best fit models are the ones when it is considered one glitch modelled by a step-function and two glitches modelled by a step-function. Conclusions: Characterizing the glitch, particularly its position, may provide information on the separation between the border of the convective core and the convective shells. This model-independent result may be used to put to test structure models of sdB stars. Keywords: subdwarfs, stars, star’s interiors, oscillations Acknowledgments: This work has been supported by Fundação para a Ciência e Tecnologia FCT/MCTES, Portugal, through national funds by these grants DOI: 10.54499/UIDB/04434/2020, DOI: 10.54499/UIDP/04434/2020 and DOI:10.54499/2022.03993.PTDC. MC is funded by FCT/MCTES by the contract with reference CEECIND/02619/2017. References [1] Cunha M. S., Avelino P. P., Christensen-Dalsgaard J., Stello D., Vrard M., Jiang C., Mosser B., 2019, MNRAS, 490, 909 [2] Baran A. S., Reed M. D., Østensen R. H., Telting J. H., Jeffery C. S., 2017, A&A, 597, A95 [3] Østensen R. H., Telting J. H., Reed M. D., Baran A. S., Nemeth P., Kiaeerad F., 2014, A&A, 569, A15 [4] Uzundag M., Baran A. S., Østensen R. H., Reed M. D., Telting J. H., Quick B. K., 2017, MNRAS, 472, 700
Title: The Very High Energy Horizon and Beyond
Author: B. Arsioli
Abstract: The very high energy (VHE) horizon is the furthest distance from which VHE gamma-rays from a source are expected to be detected. It results from the fact that gamma-rays with energies above ~30 GeV can be attenuated by the electromagnetic background light (EBL), producing electron-positron pairs. Therefore, the universe is not transparent to VHE photons, and the gamma-ray emission from extreme sources is expected to be strongly attenuated with distance. Supermassive Black Holes (SMBH) with relativistic jets pointed towards Earth (also called ‘blazars') are the dominant population of extragalactic gamma-ray emitters. Blazars do constitute the main tool to study the Very High Energy Horizon, and are the focus of this work. In this presentation I will discuss results from VHE Horizon Project, that recently got support of 100k cpu.hours secured via A1 FCT Call for Computational Resources. The project seeks to unveil E > 10 GeV blazar signatures, using data from the Fermi-LAT mission, and to identify sources at the VHE Horizon. Sources close and beyond the VHE Horizon are the most relevant for studies that investigate the mechanisms governing the gamma-ray propagation along cosmological distances. Because those are the ones that experience the most significant spectral attenuation/absorption. We will catalog those sources, and present new gamma-ray detections above 10 GeV, providing fresh candidates for VHE observatories with Cherenkov Telescope Arrays, like the upcoming CTAO.
Title: Non-linear power spectrum and forecasts for Generalized Cubic Covariant Galileon
Author: L. Atayde
Abstract: To fully exploit data from next-generation surveys, accurate modelling of the matter power spectrum up to non-linear scales is essential. We introduce the halo model reaction framework for the Generalized Cubic Covariant Galileon (GCCG) model, a modified gravity model within the Horndeski class. This model extends the cubic covariant Galileon (G3) by incorporating power laws of the scalar field derivatives in the K-essence and cubic terms. By modifying the publicly available software ReACT for the GCCG, we achieve precise predictions of the non-linear power spectrum. In the G3 model limit, our modified ReACT code shows agreement within 5% with N-body simulations across various scales and redshifts. We further analyse the impact of GCCG modifications on the non-linear matter power spectrum. Using a Fisher matrix method, we provide forecasts from spectroscopic and photometric primary probes by next-generation surveys. Our results demonstrate that future data can constrain the model's two additional parameters to the percent level at 1σ, highlighting the necessity of considering non-linear corrections beyond the linear regime to obtain this results.
Title: A Complete Characterisation of Ultra Steep Spectrum Sources in the COSMOS Field
Author: D. Barbosa
Abstract: Context. Ultra Steep Spectrum (USS) radio sources have been successfully used to select powerful radio galaxies at high redshifts (z > 2). Generally undertand that this radio excess emisson is due to a Active Galactic Nuclei (AGNs). Aims. Typically surveys of large-sky are for relatively bright radio flux densities, gradually it has gradually become possible to extend the USS search to new sensitivity levels, thanks to a new generation of radio surveys produced by Square Kilometre Array, so-called SKA-pathfinders. Methods. Combining recent observations from the MeerKAT International Gigahertz Tiered Extragalactic Explorations (MIGHTEE) and Very Large Array (VLA) at 3 GHz (10 cm) toward the two square degree Cosmic Evolution Survey (COSMOS) field, usually called VLA-COSMOS we identify more than 700 USSs, the majority of which also have optical/near-infrared measurements and redshift (spectroscopic and photometric) estimates. Using comprehensive multi-wavelength dataset available over this field, we are able to extensively characterize this population, investigate the efficiency of the USS radio criteria to reach the highest redshifts at the faintest radio fluxes, of clear relevance to the preparation of future SKA surveys. Results. We find that the faint USS source population does not show significant differences from the broader sub-mJy radio population, in particular revealing a large number of star-forming galaxies with a redshift distribution peaking at z < 1. In spite of this apparent lack of efficiency of the USS criteria in selecting very high redshift galaxies at the faintest radio flux levels, sources at very high redshifts (z > 6) are still found in our sample. This work probes the effectiveness of the USS criteria down to faint flux levels and suggests that an additional criteria can be explored for a refined selection of distant radio galaxies, in particular in the upcoming SKA-era.
Title: Relaxing constraints on neutrino masses
Author: T. Barreiro
Abstract: Experiments on neutrino flavor oscillations have established a lower limit on the cosmological energy density of thermal relic neutrinos, which is contingent on the minimum neutrino mass. Conversely, a restrictive upper limit is provided by measurements of the cosmic microwave background. We investigate the potential for relaxing the cosmological bound on the neutrino mass via an interaction with a scalar field of dark energy. Two additional parameters are introduced to account for the field's evolution and the coupling strength between the two sectors. The model is tested using Planck observations, which include the lensing potential as a probe of large-scale structure, in conjunction with BAO detection, which constrain the background evolution. Our findings indicate that the upper limit on the neutrino mass can be relaxed from ${\sum m_\nu < 0.13}$ eV to ${\sum m_\nu < 0.72}$ eV (95% CL).
Title: New insights into the population of young, massive stars near Sagittarius A*
Author: E.G. Cano
Abstract: Prior studies have revealed the presence of young massive stars in the central 0.5 pc of the Galactic Centre, prompting questions about their properties and formation in the immediate vicinity of the massive black hole Sagittarius A*. Intriguingly, the shape of the initial mass function (IMF) in this region appears to deviate from the standard Salpeter/Kroupa law. However, our knowledge of the stellar population in this challenging environment remains limited due to extreme extinction and crowding, which pose a steep hurdle to the photometric classification of stars. Spectroscopic data are available only for comparably bright sources. In this talk, we present the results of our latest study, where we employed intermediate band (IB) near-infrared imaging with the aim of enhancing our understanding of the number and distribution of young, massive stars in this region. In agreement with previous studies, but going significantly beyond them, we found a core-like distribution of late-type stars. In contrast, the density of the early-type stars increases steeply towards the black hole. The analysis revealed a top-heavy IMF for young stars within about 0.4 pc of Sagittarius A. A standard IMF may suffice at greater distances, indicating diverse star formation mechanisms at work. Additionally, we demonstrate how intermediate band photometry can serve to determine metallicities, with around 6% of the late-type stars in our sample exhibiting metal-poor characteristics.
Title: Feeding radio luminosity functions with machine learning predictions
Author: R. Carvajal
Abstract: Understanding the distribution of Active Galactic Nuclei (AGN) across cosmic time is key to disentangle the evolution of Supermassive Black Holes (SMBHs) and their link to galaxy formation. A key tool, the Radio Luminosity Function (RLF), quantifies the number density of objects within specific luminosity and redshift ranges. However, the scarcity of radio-detected AGN, especially at high redshifts, makes the construction of robust RLFs difficult. While future observatories promise to improve detection, efficient methods are needed to analyse the massive datasets they will generate and identify relevant sources. To address this challenge, Carvajal et al. (2023) developed a machine learning (ML)-based pipeline that efficiently identifies radio galaxy candidates and estimates their redshift using multi-band, multi-instrument optical and infrared (IR) photometry. This versatile pipeline can be applied across diverse regions with varying photometric coverage. We present the results of applying this ML pipeline to IR-detected sources within the Pilot Survey of the Evolutionary Map of the Universe (EMU). This technique produced an expanded catalogue of radio-detectable AGN and star-forming galaxies (SFGs). By utilising this enlarged dataset and incorporating necessary corrections, we constructed a robust RLF. This improved RLF has the potential to constrain the source density across a broader redshift range than previous efforts, leading to a deeper understanding of AGN evolution, particularly in the early Universe.
Title: A comparative analysis of HST-JWST LAEs morphology
Author: R. Cosme
Abstract: In this research project, we aim to undertake a rigorous and detailed analysis of Lyman-α emitters (LAEs) from redshifts z~2 to z~6, by using the capabilities of both the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST). Through this work, we seek to contribute significantly to understanding the pivotal transitions in galaxy morphology and the foundational role of LAEs within the cosmic timeline. This research involves an in-depth examination of LAEs identified within the SC4K survey, as well as candidates proposed through machine learning techniques within this domain. We compare the study of ultraviolet (UV) rest-frame sizes, as observed by the HST, against the optical rest-frame sizes captured by the JWST, with particular emphasis on data derived from the COSMOS-Web and the PRIMER surveys. The morphology of these galaxies is ascertained through meticulous analysis employing established galaxy modelling tools such as SourceExtractor and GALFIT. The results indicate that these sources typically display compactness in both the optical and UV rest frames, with dimensions of approximately 2 kpc and 1 kpc, respectively, in physical size. LAEs with higher rest-frame equivalent widths of Lyman-α exhibit greater compactness, suggesting a strong correlation between intense Lyman-α emission and increased star-formation rate densities, observed across both optical and UV rest frames. The escape fraction of Lyman-α photons is inclined to be greater within compact LAEs, as the photons are less prone to absorption. The elevated density characteristic of compact LAEs enables more efficient conversion of gas into stars, potentially leading to higher star-formation rates. Our thorough analysis offers new insights into galactic growth during the universe's earliest phases, establishing LAEs as key indicators of initial galactic assembly processes.
Title: Pushing the boundaries of Cool Dwarf asteroseismology with ESPRESSO
Author: R. Costa
Abstract: Asteroseismology has become an increasingly relevant way to determine the global properties of stars and peer into their inner structure, both through advances on the observational and theoretical side. Our work goes to its observational frontier by focusing on ε Indi, the coldest star in which asteroseismic modes have been detected, and, on the theoretical side, performs a detailed study of stellar and asteroseismic modelling. We focus on the surface term, a systematic error in oscillation frequencies between models and observations, whose cause will be closely linked to the unique properties of ε Indi, such as its large convective envelope along with a high density and opacity. To do this we created over 2000 stellar tracks until the end of the main-sequence using the stellar evolution code MESA, computing the asteroseismic modes for each model with GYRE. We then performed model optimization using AIMS, comparing our grid of models with the observations for ε Indi, utilizing the different options for the surface term correction available in it. This work enables us to know how asteroseismic properties such as the large and small frequency separation behave in K-type stars and how they depend on our grid parameters. To conclude that the different surface term corrections give compatible results in model optimization and about the impact that the different choices in the model physics can have on the mode frequencies, such as the atmosphere or convective efficiency.
Title: Unveiling the faintest X-ray AGN populations in the NewATHENA Era: Insights from Cosmological Simulations
Author: N. Covas
Abstract: The latest astronomical observations have propelled our understanding of galaxy formation and evolution to unprecedented depths. Despite these advancements, current facilities still face significant challenges, especially in the high-energy X-ray regime crucial for studying Active Galactic Nuclei (AGN), which prompted the development of Next Generation Observatories. ESA's future NewATHENA mission has been conceived as a powerful X-ray observatory with an unprecedented combination of collecting area, survey capabilities and energy resolution. With NewATHENA going through phase B mission definition, detailed testing campaign is necessary to ensure that it can fulfill its science goals, highly dependent on the uncertain AGN population at the highest redshifts. This research leverages the IllustrisTNG cosmological simulation to generate X-ray AGN mock catalogues tailored to test NewATHENA capabilities. By bridging the gap between theory and observations, our simulations are complementary to a purely observational approach and provide a comprehensive virtual laboratory to explore AGN characteristics and detectability. The resulting predictions will enhance NewATHENA's mission design, optimizing its ability to uncover and analyze high-redshift AGN, which are otherwise difficult to observe with existing X-ray telescopes.
Title: Ground-based direct astrometry and spectroscopy of extrasolar planets with GRAVITY
Author: P. Garcia
Abstract: The current number of known extrasolar planets of over 5700 is a considerable progress since their discovery 29 years ago. On the other hand, this is still a small number, comparable to the 5000 stars visible to the naked eye. However, these exoplanets were not detected directly. Tiny variations in the host stars' flux by eclipses and minute radial velocity wobbling of host stars orbiting the common centre of mass are the majority of the detections. This success demonstrates the power of indirect methods, and recent results show the rise of the parent star's astrometry and the probing of exoplanets' atmospheres as new indirect and robust methods. In this talk, we will focus on the direct detection of exoplanets, namely direct astrometry and spectroscopy. The power of adaptive optics has revealed many exoplanets, some on multiple outer orbits around the same host. How can we reach the inner orbits where most of the exoplanets reside? Direct spectroscopy of exoplanets with GRAVITY has been possible using the exquisite angular resolution of the Very Large Telescope Interferometer since 2019. We will present the direct spectroscopy and astrometry of HR 8799 e and how it constrains its mass, radius and temperature, as well as HIP 65426 b. A study of the HR 8799 system allows for deriving C/O ratios across separations, probing HCN and CH4, and constraining clouds in their atmospheres. The exoplanet orbiting the binary M-dwarf GJ65 is also a striking GRAVITY detection. The combination of direct and indirect methods is potent. This will be illustrated with the \beta Pic system where \beta Pic c is shown to be in a high-order mean-motion resonance. Furthermore, constraints on formation scenarios can be derived because \beta Pic is still a young system. We will also address PDS 70 protoplanets, their resonant orbit and masses, the significant dust on their atmospheres and upper limits on circumplanetary disks. Finally, Gravity directly confirmed substellar companions such as HD 206893 b, HD 206893 c, HD 72946 b, and recent Gaia predictions will be presented. We will end with an outlook into the future.
Title: Cosmological study of a symmetric teleparallel gravity model
Author: T. Gonçalves
Abstract: We study a modified gravity model able to source the accelerated expansion of the universe. We do it in the context of theories of gravity which differ from General Relativity (GR) by allowing non-metricity. Non-metric theories are based on a different geometrical description of spacetime and gravity. In some cases, this description can be equivalent to GR (Symmetric Teleparallel Equivalent of GR). However, it can also be modified beyond the GR equivalent, in order to explain some remaining open questions in cosmology. We study a non-metric gravity with a Lagrangian of logarithmic form which can source the current accelerated expansion. We consider both the evolution of the average quantities of the universe, as well as the small perturbations at the linear level.
Title: PoET, the Paranal solar ESPRESSO Telescope: a spatially resolved Sun in a high resolution spectrograph
Author: I. Leite
Abstract: There are currently important challenges imposed by stellar “noise” often associated with the discovery and characterization of exoplanets similar to Earth. In particular, various physical processes occurring on the stellar photosphere modify stellar spectra, severely challenging the detection and characterization of low-mass planets. A detailed study of the Sun can be used as a spectral proxy to a better understanding of the variable noise sources present in solar-type stars. By obtaining full integrations of the solar disk ("sun-as-a-star observations") in combination with high resolution, spatially resolved observations of smaller areas, the acquired spectra will help in the identification of individual stellar features responsible for the observed spectral deformations. The Instituto de Astrofísica e Ciências do Espaço (Portugal) is currently developing an instrument to approach this challenge. In conjunction with the high-resolution spectrograph ESPRESSO (spectral resolutions of R ~140 000 and ~190 000, HR and UHR modes, respectively), the Paranal solar ESPRESSO Telescope (PoET) will have two dedicated telescopes to map the Sun’s surface through disk resolved and disk integrated measurements, with respective telescope diameters of 600 and 75 millimeters. PoET has the requirement to perform disk-resolved observations from 1 to 60 arcseconds in conjunction with the full disk. In this work, a summary of the current configuration of the system – PoET’s telescopes and their frontends – will be given, as well as the preliminary assumptions made to build PoET, with consideration for the light requirements of the ESPRESSO spectrograph.
Title: Retrieving the transmission spectrum of a simulated transiting planet
Author: J.P. Lucero
Abstract: The study of exoplanets has advanced significantly, with over 5000 confirmed to date. Techniques like transmission spectroscopy have allowed scientists to analyze exoplanet atmospheres in detail, identifying various chemical species. However, a major challenge in this field is the "noise" from host stars, caused by stellar activity such as spots and faculae. This stellar noise can mimic or obscure signals in transmission spectra, complicating/biasing the detection and study of exoplanetary atmospheres. This work focuses on investigating the impact of non-occulted stellar spots on the transmission spectrum of WASP-76b. For this, we use the SOAP code to simulate the transit of an atmosphere-less planet, to understand how the stellar signal changes the transmission spectrum. Simulations with SOAP revealed that stellar spots significantly alter the transmission spectra, impacting the amplitude of the distortions of the lines. This approach will help us better understand the potential challenges in interpreting real data, providing a more solid preparation for the Paranal solar Espresso Telescope (PoET).
Title: The Solar System traversed the Radcliffe Wave during the Middle Miocene
Author: E. Maconi
Abstract: The ESA’s Gaia mission, a cornerstone in modern astrophysics, has revolutionized our understanding of the Milky Way by opening a new 6D window into its stellar content. This mission is providing unprecedented astrometric measurements, such as positions, parallaxes, and proper motions, for over 1.3 billion stars. Additionally, it offers high-resolution spectroscopy, detailed astrophysical parameters, and radial velocities for a subset of the brightest stars. These comprehensive datasets, augmented by earlier surveys like LAMOST and APOGEE, are instrumental in unveiling the 3D structure of our galaxy. They have enabled scientists to discover new galactic structures, including the Radcliffe Wave—a distinctive, narrow, and coherent structure of dense gas spanning 2.7 kiloparsecs in the solar neighborhood. The discovery of the Radcliffe Wave has sparked numerous intriguing questions about its origin, evolution, and, among other things, whether the Solar System interacted with this structure during its past Galactic orbit. To explore a possible interaction between the Sun and this gas structure, we identified a group of young (age<30 Myr) open clusters associated with the Radcliffe Wave and used their past trajectories over the past 30 Myr as a tracer of the Radcliffe Wave’s gas motion. Interestingly, we found that the Solar System crossed the Radcliffe Wave gas structure between 12 and 18 Myr ago, with the most likely time of transit at approximately 14 Myr ago. This finding offers an interdisciplinary connection between astronomy, geology, and climatology. Indeed, the passage of the Solar System through dense clouds can leave traces on Earth via the deposition of radioactive isotopes (mainly 60^Fe) in geological records. Moreover, the transit through a dense region of the interstellar medium would increase the amount of dust present in the inner Solar System and in Earth’s atmosphere, altering Earth's radiation budget and resulting in a cooling effect. Notably, our estimated time range for the Solar System's potential crossing of the Radcliffe Wave overlaps with the Middle Miocene Climate Transition. During this period, Earth underwent global cooling, marking its final transition to persistent large-scale continental glaciation in Antarctica.
Title: Desafios e potencialidades da divulgação de Astronomia orientada para novos públicos
Author: S. Marques
Abstract: Desafios e potencialidades da divulgação de Astronomia orientada para novos públicos Palavras-chave: Astronomia, divulgação ciência, públicos, acessibilidade O espaço para a divulgação da ciência é hoje mais amplo do que alguma vez foi. É, simultaneamente, disputado por uma quantidade inédita de contrainformação e pela pseudociência. Na era dourada do acesso à informação, a superficialidade com que se abordam tópicos científicos em geral, e também os que se relacionam com a Astronomia em contexto de ensino formal e não formal, é preocupante e parece haver indícios de uma certa estagnação no crescimento da literacia científica entre as gerações mais jovens. É cada vez mais frequente que, em sessões de planetário, ninguém na plateia tenha ouvido falar da estrela polar ou que, apesar da vasta cobertura noticiosa, se considerem ameaçadoras as auroras boreais que se observaram recentemente à nossa latitude. A multidisciplinaridade da Astronomia e o seu potencial de fascínio podem desempenhar um contributo importante não só para o esclarecimento de algumas conceções alternativas da realidade, mas também para o aumento generalizado da literacia científica e para o fortalecimento da confiança na ciência. Utilizar a Astronomia como ferramenta para atingir estes objetivos apresenta desafios. “Os desafios que a comunicação de ciência encontra na sua tarefa de divulgar o conhecimento científico são os mesmos que se encontram na divulgação da astronomia” (Anjos et. al, 2021). Em contexto de ensino formal a Astronomia tem sido cada vez menos um recurso para atingir os resultados acima referidos. No 1º Ciclo do Ensino Básico (CEB) é um tema abordado brevemente e não raras vezes com a propagação de ideias incorretas do ponto de vista científico. Identificam-se várias causas para este problema e destacam-se duas às quais os Centros de Ciência e as instituições de ensino não formal podem ajudar a dar resposta: “A falta de atualização do programa da disciplina de Estudo do Meio, quanto aos conteúdos de Astronomia, e carência de propostas didáticas consonantes com a educação em ciência.” e “O défice ao nível da formação inicial e contínua de professores, nesta área do conhecimento, colocando-os pouco à vontade para a realização de atividades práticas.”(Sá, Cristina Maria Mendes dos Santos da Fonseca e, in Formação de professores e atividades práticas de astronomia no 1º CEB, 2014). No 3º CEB o panorama também não é animador uma vez que a Astronomia deixou de constar das aprendizagens essenciais da disciplina de Ciências Naturais e é abordada apenas na disciplina de Físico-Química. Para além da capacitação de professores para que possam também aproveitar a existência de recursos inovadores para o estudo dos fenómenos astronómicos e a par da atualização dos programas curriculares das disciplinas das áreas científicas, é possível que a divulgação da Astronomia em contexto não formal venha a desempenhar um papel diferenciador no aumento da literacia científica e na confiança informada na ciência, nomeadamente pelo alcance que pode ter nos domínios do público não convencional. O UC – Exploratório – Centro Ciência Viva da Universidade de Coimbra tem vindo a procurar dar resposta às lacunas identificadas através da realização de workshops para professores e alunos e através da abordagem de temas no âmbito da Astronomia em várias atividades realizadas para diferentes públicos. As sessões de planetário para escolas e para visitantes livres em contexto familiar, as observações noturnas, as atividades em tempo de férias escolares, as idas às escolas com o Hemispherium Viajante são disso exemplo. Para além desta oferta, que é basilar, o UC - Exploratório procura ainda ir ao encontro daquilo que pode ser designado como público não convencional. Esta designação pretende englobar o público que não frequenta habitualmente os Centros de Ciência nem participa das suas atividades. As razões para este facto podem ser olhadas por duas perspetivas - por um lado, o eventual desinteresse na temática ou desconhecimento das atividades, e por outro o condicionamento económico, social, cultural, motor ou outro. Para ir ao encontro de alguns segmentos que integram o leque dos novos públicos, o UC-Exploratório tem desenvolvido programas com resultados animadores. Estreámos em 2016 o projeto “Astronomia para Bebés – Sentir o cosmos em família”, que foi distinguido com o prémio internacional Mariano Gago Ecsite Awards 2018 na categoria Smart and Simple. Este projeto permitiu dar resposta à falta de oferta para a faixa etária dos zero aos três anos, segmento para o qual, regra geral, não se programam atividades de divulgação de Astronomia. A projeção full dome, que foi a primeira produção original do UC-Exploratório e está em exibição até hoje, permite aos bebés o deslumbramento com algumas das mais belas paisagens do universo e cria a oportunidade para que também os adultos que os acompanham vejam despertada a curiosidade por alguns tópicos das ciências do espaço. Este projeto conta já com a segunda edição, com banda sonora original de Maria João e João Farinha e ilustrações de Cristina Sampaio. Com este projeto estabelecemos uma parceria com a Cité des Sciences et de l´Industrie de Paris no âmbito da Temporada Portugal - 2022. Em exibição no UC – Exploratório esteve o filme “Prontos para a descolagem!”, produzido pela equipa do planetário da Cité, e em Paris foi exibida uma versão adaptada da “Astronomia para Bebés”. Em 2018, o programa “Quando o Céu quiser” permitiu-nos ir ao encontro de centenas de pessoas que nunca tinham observado o céu. Foram realizadas 16 sessões em parques urbanos de várias cidades do interior do país, de forma gratuita e sem divulgação prévia. Foi privilegiado o contacto com o público que, de outra forma, não estaria presente naquele momento, em detrimento das condições ótimas de observação. Foi, para maioria dos participantes, a primeira vez que fizeram uma observação com um telescópio, a primeira vez que viram uma constelação ou um planeta. Em 2019, levámos o Hemispherium Viajante ao Hospital Pediátrico de Coimbra onde dinamizámos projeções de filmes e sessões de Astronomia para crianças em contexto de internamento prolongado. Estas crianças, cognitivamente ativas, tiveram oportunidade de explorar o Sistema Solar e de conhecer as constelações apesar dos constrangimentos físicos e emocionais que enfrentavam à data. O UC-Exploratório acolhe desde Maio de 2022 a Escola Ciência Viva dedicada ao pré-escolar, onde a temática da Astronomia é um tema residente em todas as semanas de atividades. São abordados conceitos como as viagens espaciais, a gravidade, os planetas do Sistema Solar, as fases da Lua, os meteoritos e as crateras lunares. Os educadores descrevem as atividades como muito enriquecedoras. As crianças iniciam o processo de conceptualização destes temas tão abstratos, familiarizando-se com eles; tiram o maior proveito das dinâmicas práticas e interativas que são levadas a cabo. Acreditamos que há ainda um leque bastante vasto de sectores onde podemos ambicionar chegar em colaboração com o ensino formal. A integração de alunos estrangeiros é um exemplo desse potencial – o caráter universal da Astronomia permite que se ultrapassem barreiras linguísticas e a sua multidisciplinaridade permite que, a partir dela, se abordem temas tão diversos como a História, a Antropologia e até a Arte. Alguns alunos têm nas sessões de planetário uma oportunidade de expor o seu conhecimento e têm momentos (muitas vezes os primeiros) onde se sentem a par dos seus colegas. Do ponto de vista social, e ao encontro de novos públicos, os desafios são ainda maiores. A Astronomia pode dar também um contributo para a coesão social, colaborando com instituições que prestam serviço às comunidades mais desfavorecidas. Não só é necessário responder às necessidades básicas dos cidadãos, mas importa considerar o conhecimento como uma necessidade básica. São as comunidades vulneráveis as mais permeáveis à desinformação e à adesão a ideias erradas do ponto de vista científico. O alargamento do alcance da divulgação da Astronomia pode ser uma ferramenta determinante no cumprimento destes objetivos. Anjos, S., Russo, P. and Carvalho, A. (2021). Communicating astronomy with the public: perspectives of an international community of practice JCOM 20(03), A11. Sá, Cristina Maria Mendes dos Santos da Fonseca e, (2014), Formação de professores e atividades práticas de astronomia no 1º CEB
Title: Refining the Radial Velocity method to uncover other Earths
Author: C. Martinez
Abstract: The quest to detect and characterize other Earths drives advancements in astrophysics. Yet, this endeavor faces challenges due to astrophysical ”noise” from host stars distorting spectra.Current methods lack detailed understanding of the variability sources behind this “noise”. This project will employ a novel approach by using high-resolution spectra of the Sun observed at various scales. This will be possible exclusively by the PoET telescope under the leadership of the supervisor’s team, when integrated with the ESPRESSO spectrograph at ESO’s Paranal observatory. This PhD project aims to prepare for PoET’s data, focusing on understanding spectral lines’ sensitivity to different stellar activity phenomena causing ”stellar noise” in ultra-high precision Doppler radial velocity measurements. The goal is to develop methods for measuring radial velocities of solar-type stars down to 10 cm/s, crucial for detecting rocky, temperate planets. Insights gained will be applied to existing datasets, searching for signals indicating low-mass, rocky planets orbiting solar-type stars.
Title: On the Selection and Exploration of Radio Powerful Active Galactic Nuclei
Author: P.M. Martins
Abstract: One of the fundamental questions in astronomy is how galaxies form and evolve through cosmic time. For the past few decades, various teams have tried to answer this question by constructing computational models for simulated galaxies and their associated active galactic nuclei (AGN). With the next generation of telescopes currently developing survey strategies with a strong emphasis on exploring the early Universe (e.g., Athena in the X-ray and SKA in the radio regime), it is of the utmost importance to explore the predictions from state-of-the-art galaxy formation and evolution models, in particular at the Epoch of Re-ionization (EoR). This project looks to implement improved recipes for radio emission, taking into account the most recent advances in our understanding of black hole accretion physics, together with current models for SMBH and galaxy evolution (e.g., EAGLE, GALFORM, Millennium). With these recipes, we will define new, more efficient criteria for the selection of AGN from radio observations, out to very high redshifts, allowing us to identify and analyze robust candidates for high redshift radio AGN in very sensitive surveys currently being performed (e.g., SKA Pathfinder and MeerKAT). This will allow us to optimize the design of the upcoming generation of whole-sky radio surveys, currently being developed for the future Square Kilometre Array telescope. In parallel, this project is implementing a monitoring campaign of nearby AGN, using the Santa Maria radio telescope, part of the RAEGE network. This will complement the above approach by setting the framework to further explore the physical mechanisms behind AGN radio emission, as revealed by AGN variability. Here, the project will aim to perform a census of AGN monitoring efforts being made worldwide, in order to identify the best strategy for this program. We will also identify the impact of variability studies in the AGN accretion physics and evaluate how this can lead to improved recipes for radio emission.
Title: Quantitative constraints on geometric extension of general relativity
Author: P. Monteiro
Abstract: We study physical solutions of a modified gravity cosmological model based on a geometric generalization of general relativity using a Yano-Schrödinger connection. Extra terms in the Friedmann equation are interpreted as an effective geometric dark energy. Moreover, using low-redshift background cosmology data, including Type Ia and Hubble parameter data, we place constraints on the parameters of this class of dark energy models, aiming to explain the low-redshift acceleration.
Title: Dissecting Stellar Populations with Manifold Learning
Author: A.W. Neitzel
Abstract: Stellar populations distinguish themselves from one another via differences in chemical, kinematic and chronological properties, suggesting an interplay of different physical mechanisms that led to their origin and subsequent evolution. As such, the identification of stellar populations is key for gaining insight on the evolutionary history of the Milky Way galaxy. This task is made complicated by the fact that stellar populations share significant overlap in their chrono-chemo-kinematic properties, which hinders the ability to both identify and define stellar populations. To tackle this problem, we explore use cases of manifold learning, a type of unsupervised machine learning application which seeks to intelligently identify and disentangle manifolds hidden in the input data. To test the method, we make use of Gaia DR3-like synthetic stellar samples generated from the FIRE-2 cosmological simulation. We show that manifold learning possesses promising abilities to differentiate stellar populations, even when considering realistic observational constraints.
Title: Impact of nebular contribution to stellar mass determination
Author: C. Pappalardo
Abstract: The launch of JWST two years ago has opened new paths for the exploration of the galaxy's evolution, and the lines of investigation are multiplying as long as new JWST data arrive. With the ongoing projects and the new ones to be decided in the next call, the number of galaxies observed is reaching a reasonable statistical accuracy, allowing the investigation of the evolution of the well-known scaling relations extensively explored in the low redshift regime. On another note observing galaxies in their near-infrared rest frame will allow more refined stellar mass determination, but there is a point to consider. Galaxies at high redshift are observed in an epoch where galaxies are forming more stars than low redshift regimes. Higher star formation implies a higher contribution from the nebular gas to the total emission observed. During strong star formation episodes, the continuum produced by the nebular gas can have a relevant contribution to the overall observed continuum. This in turn affects the stellar mass determination in spectral fitting codes that estimate the continuum considering only the stellar component. At low redshift, this effect has been observed in green pea galaxies and blue compact dwarfs, but this condition, a little bit extreme in the nearby Universe, can be quite common in the early Universe, as shown by the high value of Equivalent width found in many JWST galaxies. In this talk, I will describe the work ongoing in Lisbon, where with a team of PhD and master's students and thanks to an in-house code that fits simultaneously the stellar and the nebular contribution in a spectrum, we are exploring the impact of the nebular contribution to the estimation of stellar masses. Starting from the well-known spectra taken from the SDSS sample, we have shown that there exists a correlation between the nebular contribution to the overall continuum and the difference between the stellar mass determined with purely stellar codes and codes including the nebular contribution. The results show that these discrepancies start to be not negligible when the Equivalent Width of Halpha, EW(Ha), reach a value above 500 Angstrom, which is quite uncommon in the nearby Universe, but it can be easily achieved for all the so-called 'extreme emission line galaxies', with EW that can reach 1000/2000 Angstrom. Our work shows that the mass estimation obtained via spectral fitting could have, at least for a subsample of the overall population, produced an overestimation of the total mass. This overestimation can achieve a factor of 3/5 for galaxies with EW(Ha) > 1000 Angstrom reaching an order of magnitude for galaxies above EW(Ha) > 1000 Angstrom. This could have an impact on the determination of the stellar mass function at higher redshift, with important implications for the current galaxy evolution models.
Title: Matter and Anti-matter asymmetry dilemma, a possible solution from modified gravity
Author: D. Pereira
Abstract: The matter and anti-matter asymmetry conundrum is one of the most significant problems in modern physics. Mechanisms that generate this asymmetry during the early stages of the Primordial Universe, commonly referred to as Baryogenesis mechanisms, are the best answer to this puzzle. These mechanisms are mainly based on particle physics and famous ones like Electroweak Baryogenesis (EWB) and Baryogenesis from Grand Unification Theories (GUTB) stood out as strong candidates to solve the asymmetry problem. However, their constraints and shortcomings lead to the search for new mechanisms. Of the new mechanisms developed, Gravitational Baryogenesis (GB) appeared as one of the first mechanisms to display a direct relation between asymmetry production and gravity through a gravitational interaction of the derivative of the Ricci scalar curvature and the Baryonic current. The resultant asymmetry is intricately linked to the gravitational field equations and the cosmological framework employed. Thus, modifications to the theory of gravity can influence the asymmetry generation process offering insights into the underlying mechanism. Furthermore, it is conceivable that the shortcomings of EWB and GUTB can potentially be mitigated through a modification of the theory of gravity. In this work, we have explored how scalar-tensor theories can help EWB and GUTB and the impact of non-minimal geometry-matter coupled theories in the context of Gravitational Baryogenesis.
Title: Stability of the OGSE Vis-NIR Illumination Sub-System for the future ARIEL Space Mission
Author: C. Pereira
Abstract: The future ARIEL Space Mission aims to achieve photometric precision down to the parts-per-million (ppm) level over periods longer than ten hours. This level of sensitivity is crucial to obtain valuable information about the properties of the exoplanet and its atmosphere. Achieving such precision requires a very precise characterisation of the instruments aboard of ARIEL, which can only be done with highly stable illumination systems, supported by ultra-low noise reference detectors. The Institute of Astrophysics and Space Sciences is responsible for the development of the visible and near-infrared (Vis-NIR) illumination sub-system, integrated into ARIEL’s Optical Ground Support Equipment (OGSE), responsible for covering a wavelength range from 0.5 µm to 1.95 µm. Since ARIEL has a broadband wavelength coverage, from 0.5 µm to 7.8 µm, the OGSE includes other calibration sources, all integrated through an integrating sphere and monitored by reference detectors. This study presents an in-depth analysis of two main components of the Vis-NIR illumination sub-system: a Quartz Tungsten-Halogen (QTH) calibration source and an extended Indium Gallium Arsenide (InGaAs) reference detector. The stability and behaviour of the light source, both in flux and in spectrum, are evaluated, and the performance of the reference detector, integrated with a zero-drift pre-amplifier, is tested under cryogenic conditions. It is shown that these two components are compliant with the ARIEL’s requirements, allowing the mission to obtain spectroscopic and photometric time series, with the stability needed to identify signal variations from 20 ppm to 100 ppm, over a 10-hour observation period.
Title: Fuelling supermassive black holes with misaligned gas
Author: S. Raimundo
Abstract: Identifying black hole gas fuelling mechanisms is important to understand how supermassive black holes grow and what physical conditions favour the onset of black hole activity. However, it is challenging to find clear observational signatures of black hole fuelling or 'feeding'. In this presentation I will show that galaxy interactions, such as major mergers, minor mergers or galaxy flybys, provide the necessary conditions to fuel black hole activity. I will describe how we use kinematically misaligned gas to observationally identify galaxies that went through an interaction. With this method we have recently shown that galaxies with misaligned gas have a higher observed fraction of active supermassive black holes. This is the first time that an observational connection is seen between the presence of misaligned structures and the fuelling of active supermassive black holes, indicating that gas from external interactions can be transported across the galaxy and all the way to the central black hole. In this presentation I will also discuss how luminous these active black holes are, and the implications of this black hole fuelling mechanism for different galaxy types and their evolution.
Title: THE PORTUGUESE ASTRONOMY OLYMPIAD
Author: G. Rojas
Abstract: We report the results of the 18th Portuguese Astronomy Olympiad, which in 2024 involved 116 secondary school students.10 of these students were selected for the national final round, which in turn selected 5 students do represent Portugal in the XVII International Olympiad on Astronomy and Astrophysics, held at Vassouras, Brazil. We also report the 2nd edition of the Junior Olympiad, which attracted a record number of over 600 students of 7th and 8th grade. We’ll discuss the performance of the students and the feedback received from them as well as from the teachers. We’ll also present preliminary results based on testimonials from past participants on the impact of the Olympiad on their higher education choices.
Title: Neither icy nor terrestrial: Exploring the nature of steam worlds
Author: B. Soares
Abstract: As the number of exoplanets found gradually increases, so does the types of planets existing, leading to a very diverse population. While the formation processes of some are thought to be known, others remain yet to be explained. Such is the case of steam worlds, planets mostly composed by rocky material but with a non-negligible atmosphere partially composed by water. In this talk I will discuss the specific conditions under which this type of planets may exist, and explore the possibility of these planets being the consequence of evolution of other planets or rather them being a different population on their own.
Title: Joint cosmological constraints from the Canonical and Differential Redshift Drifts
Author: M. Sousa
Abstract: The redshift drift of celestial objects following the Hubble-Lemaître flow is model-independent probe of the expansion history of the universe, also providing constraints on the parameters of various cosmological models. A further possibility, using a non-zero reference redshift, is known as the differential redshift drift. In preparation for the measurements by the ANDES spectrograph at the ELT and secondarily by the SKA, we used Fisher Matrix based techniques to study the sensitivity of both redshift drift and differential redshift to cosmological modelis including the curvature parameter, showing an asymmetry in the sensitivity between open and closed universes. We then consider the ELT Golden Sample of Cristiani et al. and provide detailed forecasts for joint measurements of the canonical and differential redshift drifts.
Title: Type la Supernovae host galaxies: a local vs global perspective of host galaxy effects on SN Ia luminosity using VLT/MUSE IFS data
Author: J.M. Sousa
Abstract: Background & Aim: Type Ia Supernovae hold paramount importance as standard candles within the field of cosmology, yet the robustness of their luminosity as a calibration measure can be subject to the characteristics inherent to their host galaxies. This research project delves into an in-depth comparative study of the local and global properties within SN Ia host galaxies, aiming to delineate their influence on supernova brightness, using the comprehensive, high-resolution data obtained through Integral Field Spectroscopy (IFS) via the MUSE instrument on the Very Large Telescope (VLT). Methods: Utilizing advanced, IFS data, we implement a detailed spaxel-by-spaxel analysis, meticulously examining individual spatial pixel elements (spaxels) to reveal unique spectral signatures within these galaxies. Stemming from an intensive high-performance computing project, this technique allows a meticulous, pixel-by-pixel investigation of the galaxies, striving to illuminate the complex relationship between local environmental factors - such as stellar mass, metallicity, and star formation rates - and their overarching influence on SN Ia luminosity. Results: (Preliminary results) We arrive to the conclusion that certain aspects are systematically underestimated. We used the newly derived corrections as a function of redshift to make corrections of a known sample of SN Ia hosts and derive cosmological parameters. We show that these corrections have a small impact on the derived cosmological parameters. While the systematic errors found do not significantly affect the derived cosmological parameters, it is an important source of systematic error that needs to be corrected for as we enter a new era of precision cosmology. Conclusions: Ultimately, by deepening our understanding of these intricate correlations, this study aspires to bolster the use of SN Ia in precision cosmology, providing more definitive insights into the mechanisms driving cosmic expansion and the fundamental nature of the universe.
Title: Where in the Milky Way do exoplanets preferentially form?
Author: J. Teixeira
Abstract: Exoplanets are detected around stars of different ages and birthplaces within the Galaxy. The aim of this work is to infer the Galactic birthplaces of stars and, consequently, their planets, with the ultimate goal of studying the Galactic aspects of exoplanet formation. We used photometric, spectroscopic, and astrometric data to estimate the stellar ages of two samples of stars hosting planets and, for comparison, a sample of stars without detected planets. The Galactic birth radii of exoplanets were inferred by projecting stars back to their birth positions based on their estimated age and metallicity. We find that stars hosting planets have higher metallicity, are younger, and have a smaller Galactic birth radius compared to stars without detected planets. In particular, stars hosting high-mass planets show higher metallicity, are younger, and have a smaller Galactic birth radius than stars hosting low-mass planets. We show that the formation efficiency of planets, calculated as the relative frequency of planetary systems, decreases with the galactocentric distance, for which this relation is stronger for high-mass planets than for low-mass planets. We found that the formation efficiency of high-mass planets increases and encompasses a larger galactocentric distance over time. While the formation efficiency of low-mass planets only shows an increase between the ages of 4 and 8 Gyr and also encompasses a larger galactocentric distance over time. Stars without detected planets appear to form at a larger galactocentric distance over time. We conclude that the formation of exoplanets throughout the Galaxy follows the Galactic chemical evolution, for which our results are in agreement with the observed interstellar medium (ISM) negative gradient and its enrichment and flattening with time at any radius.
Title: Boosting Lyman-α Identification and Characterization in the Era of Large Surveys
Author: A. Vale
Abstract: Background & Aim: Finding Lyman-alpha emitting galaxies (LAEs) in large numbers usually entails dedicated surveys using custom narrow-band filters. Additionally, as current and future surveys are set to produce huge data volumes, AI-driven decisions are increasingly necessary within the decision-making framework. Methods: Our methodology revolves around employing gradient-boosting algorithms trained on data from the COSMOS2020 catalogue (Weaver et al., 2022) and SC4K survey (Sobral et al., 2018) using broadband photometry (magnitudes, fluxes and colors) in the optical and NIR. We construct balanced datasets with similar redshift and i-band distributions to train and test our model. Results: We achieve an impressive accuracy and F1-score ranging between ~85-90%. Our classification model not only effectively separates LAEs from similar generic populations but also demonstrates promise for pre-selecting potential LAEs in forthcoming large-scale surveys like EUCLID or LSST. Furthermore, we also assess the robustness of our model against minor perturbations in the data, a crucial quality measure for machine learning models, as these perturbations may induce classification failures that result in poorer performances. Aside from selecting new potential candidates, we also train regression models to get a first approximation of the overall sample properties (redshift, Lya line luminosity and equivalent width) with a good performance. Specifically, we achieve a mean absolute error lower than 0.18 for redshift and Lya line luminosity and smaller than 0.25 for the equivalent width. Conclusions: Overall, our approach is efficient in identifying and characterizing LAEs and also facilitates a comprehensive discussion on the fundamental photometric attributes underpinning the study of these galaxies using machine learning and also the limitations inherent in these methodologies and ways to overcome them in a near future.
Title: Current and future cosmological impact of microwave background temperature measurements
Author: A.M. Vieira
Abstract: The redshift dependence of the cosmic microwave background temperature, 𝑇(𝑧)=𝑇0(1+𝑧), is a key prediction of standard cosmology, but this relation is violated in many extensions thereof. Current astrophysical facilities can probe it in the redshift range 0≤𝑧≤6.34. We extend recent work by Gelo et al. (2022) showing that for several classes of models (all of which aim to provide alternative mechanisms for the recent acceleration of the universe) the constraining power of these measurements is comparable to that of other background cosmology probes. Specifically, we discuss constraints on two classes of models not considered in the earlier work: a model with torsion and a recently proposed phenomenological dynamical dark energy model which can be thought of as a varying speed of light model. Moreover, for both these models and also for those in the earlier work, we discuss how current constraints may be improved by next-generation ground and space astrophysical facilities. Overall, we conclude that these measurements have a significant cosmological impact, mainly because they often constrain combinations of model parameters that are orthogonal, in the relevant parameter space, to those of other probes. This work has been published in Phys. Dark Univ. 44 (2024) 101494.