Program

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{"title":"Day 1 - Thursday, September 12","rows":[{"time":"08:30 - 08:45","separator":true,"expanded":false,"cols":[{"title":"Registration","bold":true,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"08:45 - 09:00","separator":true,"expanded":false,"cols":[{"title":"Welcoming session","bold":true,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"09:00 - 10:00","separator":false,"expanded":false,"cols":[{"title":"Shadow of the moon and general relativity: The 1919 gravitational light deflection with its protagonists","bold":false,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"},{"title":"José Sande Lemos","bold":false,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"10:00 - 11:00","separator":false,"expanded":false,"cols":[{"title":"Eddington and modern galactic astronomy","bold":false,"expandable":true,"expanded":false,"content":"Eddington worked intensively on stellar kinematics and dynamics in the years prior to the famous expedition to Principe in 1919. This was before the status of the Milky Way as an island galaxy in a much larger Universe had even been established. All the more astonishing that some of the techniques introduced by Eddington over a century ago have driven recent developments in modern Galactic structure. The European Space Agency's Gaia satellite scans the sky as I write. It is providing abundant stellar kinematical data that Eddington could scarcely have imagined. Interpretation of this data, using tools and ideas introduced by Eddington, has enabled us to decode the violent history of our Galaxy back to 10 billion years ago.","url":"","url_title":""},{"title":"Wyn Evans","bold":false,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:00 - 11:30","separator":true,"expanded":false,"cols":[{"title":"Poster Session and Coffee Break","bold":true,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Compact Objects and Black Holes","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:30 - 11:45","separator":false,"expanded":false,"cols":[{"title":"Light and heavy clusters in core-collapse supernovae and neutron star mergers","bold":false,"expandable":true,"expanded":true,"content":"In the near future, the large amount of new data that will be made available by SKA will allow us to determine neutron star properties with much smaller uncertainties and set strong constraints on the equation of state of stellar matter. Neutron stars will, as a consequence, become a real laboratory to test the nuclear force under extreme conditions of density, proton-neutron asymmetry and temperature. Light (deuterons, tritons, helions, α-particles), and heavy (pasta phases) nuclei exist in nature not only in the inner crust of neutron stars (cold beta-equilibrium matter), but also in core-collapse supernova matter (warm nuclear matter with fixed proton fraction). The appearance of these clusters can modify the neutrino transport, and, therefore, consequences on the dynamical evolution of supernovae and on the cooling of proto-neutron stars are expected. \nIn this talk, light and heavy clusters are calculated for warm stellar matter in the framework of relativistic mean-field models, in the single-nucleus approximation. In-medium effects of light cluster properties are included by introducing an explicit binding energy shift analytically calculated in the Thomas-Fermi approximation, and the coupling constants are fixed by imposing that the virial limit at low density is recovered. The resulting light cluster abundances come out to be in reasonable agreement with constraints at higher density coming from heavy ion collision data. Some comparisons with microscopic calculations are also shown.","url":"","url_title":"Download"},{"title":"Helena Pais","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:45 - 12:00","separator":false,"expanded":false,"cols":[{"title":"Astrophysical constraints on the dark matter core inside the neutron stars","bold":false,"expandable":true,"expanded":true,"content":"We study an impact of asymmetric dark matter on properties of the neutron stars and their ability to reach the two solar masses limit, which allows us to present a new upper constraint on the mass of dark matter particle. Our analysis is based on the observational fact of existence of three pulsars reaching this limit and on the theoretically predicted reduction of the neutron star maximal mass caused by accumulation of dark matter in its interior. Using modern data on spatial distribution of baryon and dark matter in the Milky Way we argue that particles of dark matter can not be heavier than 5 GeV. We also demonstrate that light dark matter particles with masses below 0.2 GeV can create an extended halo around the neutron star leading not to decrease, but to increase of its visible gravitational mass. Furthermore, we predict that high precision measurements of the neutron stars maximal mass near the Galactic center, will put a stringent constraint on the mass of the dark matter particle. This last result is particularly important to prepare ongoing, and future radio and X-ray surveys.","url":"","url_title":""},{"title":"Violetta Sagun","bold":false,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:00 - 12:15","separator":false,"expanded":false,"cols":[{"title":"Electrically charged, anisotropic strange quark stars: Exact analytical solution","bold":false,"expandable":true,"expanded":false,"content":"We obtain a new exact analytical solution to the Einstein-Maxwell field equations with anisotropic matter. The solution describes the interior of anisotropic, electrically charged strange quark stars with a non-linear equation-of-state. We show graphically the behaviour of the solution, and we determine the properties of the star (radius, mass, electric charge and compactness) for specific numerical values of the parameters involved. Finally we check that causality is not violated, and that the energy conditions, the upper bound on the compactness of the stars, and constraints on the mass of the objects coming from observed massive pulsars and direct detection of gravitational waves are all fulfilled.","url":"","url_title":"Download"},{"title":"Grigorios Panotopoulos","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:15 - 12:30","separator":false,"expanded":false,"cols":[{"title":"Energy extraction from rotating black holes through particle collisions","bold":false,"expandable":true,"expanded":false,"content":"Energy extraction from black holes via Penrose process requires production of particles with high relative velocity, which is likely to happen in high-energy collisions. Collisional Penrose process thus received a lot of attention when Bañados, Silk and West (BSW) pointed out the possibility of near-horizon collisions of test particles with arbitrarily high centre-of-mass energy. Furthermore, an electrostatic analogy of the original centrifugal BSW effect was later described by Zaslavskii. Nevertheless, both variants have serious drawbacks. For the centrifugal version, unconditional upper bounds exist on the energy (and mass) of escaping particles. Although no such bounds were found for the electrostatic variant, it is impractical for astrophysical purposes, since it involves the maximally charged black holes. Realistic black holes can, however, have only a small amount of charge, acquired through interaction with external magnetic field due to Wald's charging mechanism. Our work focuses on studying energy extraction via collisional processes involving charged particles moving around black holes with both spin and charge. In the present talk, we demonstrate that escape of particles with high energy is indeed possible for arbitrarily small value of the black hole charge.","url":"","url_title":"Download"},{"title":"Filip Hejda","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:30 - 12:45","separator":false,"expanded":false,"cols":[{"title":"Black holes in degenerate higher-order scalar-tensor theories","bold":false,"expandable":true,"expanded":true,"content":"We study static spherically symmetric black hole solutions with a linearly time-dependent scalar field and discuss their linear stability in the shift- and reflection-symmetric subclass of degenerate higher-order scalar-tensor (DHOST) theories. We present the explicit forms of the reduced system of background field equations for a generic theory within this subclass. Using the reduced equations of motion, we show that in several cases the solution is forced to be of the Schwarzschild or Schwarzschild-(anti-)de Sitter form. We consider odd-parity perturbations around general static spherically symmetric black hole solutions, and derive the concise criteria for the black holes to be stable. Our analysis also covers the case with a static or constant profile of the scalar field.","url":"","url_title":"Download"},{"title":"Masato Minamitsuji","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:45 - 14:30","separator":true,"expanded":false,"cols":[{"title":"Lunch","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Planetary Sciences","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"14:30 - 14:45","separator":false,"expanded":false,"cols":[{"title":"Asynchronous and chaotic rotation for compact planetary systems","bold":false,"expandable":true,"expanded":true,"content":"We study the spin evolution of close-in planets in compact multi planetary systems. The rotation period of these planets is often assumed to be synchronous with the orbital period due to tidal dissipation. Here we show that planet-planet perturbations can drive the spin of these planets into non-synchronous or even chaotic states. These asynchronous configurations are possible even for nearly circular orbits and will impact the habitability of these planets. We also present a very simple method to probe the spin dynamics from the orbital perturbations.","url":"","url_title":"Download"},{"title":"Alexandre Correia","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"14:45 - 15:00","separator":false,"expanded":false,"cols":[{"title":"A Bayesian approach to the processing of stellar occultations","bold":false,"expandable":true,"expanded":true,"content":"Asteroids are involved in understanding several key issues in Solar System science and the space environment of our planet, such as the conditions of the Solar System during its formation, the delivery of water and organic molecules to Earth, the potential danger of Near Earth Asteroids (NEA) and their role in affecting Earth’s climate. Stellar occultation events are a unique opportunity to obtain from the ground very accurate asteroid astrometry, close to the performance of Gaia, and shapes/sizes. When an asteroid hides the light of a star, the uncertainty of its instantaneous position can be similar to that of the target star. By exploiting the accuracy of Gaia DR2 on both asteroids and stars, stellar occultation prediction and exploitation becomes an effective method to systematically collect asteroid astrometry. The improvement of predictions through Gaia DR2 is proven via statistics of real predictions and comparison between stellar occultation predictions with Gaia DR2 for asteroids and other, such as Astorb and MPCORB, to verify which fit better to observed chords of past occultations. At the same time, asteroid occultations can offer the possibility to confirm or discover double stars, in a range of small angular separations very complementary to the resolution accessible to Gaia itself. We will present statistics and simulations showing the improvement expected in the prediction of asteroid occultations thanks to Gaia astrometry, in particular regarding the smaller uncertainties on the proper motion of target stars.Through a bayesian approach, we determine in the parameter space (duration ; flux drop ; star brightness) the domain of detectable events from a single site. Our study prepares the exploitation of the 0.5-m robotic telescope at \"Plateau de Calern\" (Southern France) Universcity, for which we determine the range of asteroid size and star brightness that we expect to reach. This facility will start operations in a few months.After this work simulating the expected performance of Universcity with the available equipment, the plan is to apply these limitations to predicted events and maximize the efficiency of the telescope’s use.","url":"","url_title":"Download"},{"title":"João Ferreira","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:00 - 15:15","separator":false,"expanded":false,"cols":[{"title":"Comparative study of circulation regimes of terrestrial planets' atmospheres","bold":false,"expandable":true,"expanded":false,"content":"Understanding our Solar System Planetary Atmospheres is a significant step forward for paving the way for future studies of Extrasolar Planets' atmospheres. Notably, Venus and Mars are natural comparative laboratories to investigate diversity of circulation regimes of terrestrial planets' atmospheres. In this context, comparative studies are essentials to understand the evolution of climate on Earth, both in the past and in the future. Notably, Venus and Mars are natural comparative laboratories to investigate diversity of circulation regimes of terrestrial planets' atmosphere. Venus for example, is Earth’s closest sibling but it has ended up with a radically different climate. Venus atmospheric science is thus increasingly important in an era in which we are trying to understand the divergent evolutionary outcomes for terrestrial planets, whether we are considering the future of our Earth or the habitability in other planetary systems. We will present a study based on large scale and small scale processes going on the middle/upper atmosphere of Venus and Mars combining wind measurements and 3D model simulations. Venus is a slowly rotating planet with a dense atmosphere. The mechanisms for the generation and maintenance of superrotation are still unclear and no model has been able to successfully reproduce its circulation in decades (Lebonnois 2013). A proper monitoring of Venus winds is crucial towards a full understanding of this phenomena. With this aim, we intend to conduct a synthesis effort that could provide important constraints on atmospheric models. In Venus’s mesosphere (65-85 km), visible observations of Doppler shifts in solar Fraunhofer lines, based on high-resolution spectra, have provided the only Doppler wind measurements near the cloud tops in recent years (Machado et al. 2014, 2017). We will present wind measurements based on VLT/UVES and CFHT/ESPaDOnS observations (around 70 km), wind measurements based on Akatsuki space probe data (and ESA's Venus Express archive data) with cloud tracking methods (from 48 km till 70 km), using an improved version of a cloud tracking tool based on phase-correlation between images. The objective of this work is to help constrain the planetary atmospheric characterization, and to take a step forward in the comparative studies of terrestrial planets.","url":"","url_title":"Download"},{"title":"Pedro Machado","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:15 - 15:30","separator":false,"expanded":false,"cols":[{"title":"Characterising atmospheric gravity waves on Venus","bold":false,"expandable":true,"expanded":false,"content":"On this talk, we will report on the detection and characterisation of atmospheric gravity waves on the lower and upper cloud deck of Venus using images from the Venus Monitoring Camera (VMC) and the Visible Infrared Thermal Imaging Spectrometer (VIRTIS). This work is intended to follow-up on the reports by Peralta, J., et al. (2008) and Piccilli, A., et al. (2014) going through the complete VIRTIS and VMC data sets to fully characterise gravity waves observed during the Venus Express mission. Images were navigated and processed for optimal detection of wave features and accurate characterisation of wave properties such as horizontal wavelength, packet length and width, orientation and where possible phase velocity of the wave packet.","url":"","url_title":"Download"},{"title":"José Silva","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:30 - 15:45","separator":false,"expanded":false,"cols":[{"title":"Beyond the exoplanet mass-radius relation","bold":false,"expandable":true,"expanded":true,"content":"The mass and radius are two fundamental properties to characterize exoplanets. For a large number of exoplanets, either the radius or the mass is unknown, while the host star has been characterized. \nI used a machine learning algorithm and a database of confirmed exoplanets with known planetary and host star parameters, to compute the radius of exoplanets and compare the results to the published radii. \nI will show that the estimated radii reproduce the spread in radius found for high mass planets better than previous mass-radius relations, with an average error of 2 R⊕ across the whole exoplanet range. I will demonstrate that the exoplanet’s mass and equilibrium temperature are the relevant properties which constrain the radius and that the random forest algorithm is a promising method to derive exoplanet properties.","url":"","url_title":"Download"},{"title":"Solène Ulmer-Moll","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:45 - 16:00","separator":false,"expanded":true,"cols":[{"title":"Stellar activity of the AMBRE-HARPS sample: preliminary results","bold":false,"expandable":true,"expanded":false,"content":"The AMBRE project is a collaboration to determine the stellar atmospheric parameters of the archived spectra of four ESO spectrographs. In this context we aim to study the stellar activity of the ESO-HARPS sample. We are interested in evaluating activity and, using time-series and stellar parameters, determining the rotational and magnetic cycle periods of the stars. Stellar activity, rotation and magnetic cycles are inter-connected and can give information about the origin and evolution of stars. Furthermore, these parameters are very important for the detection and characterisation of extra-solar planets since stellar activity is one of the main sources of stellar noise, which hampers planet detection, but also plays a role on exoplanet habitability.","url":"","url_title":"Download"},{"title":"João Gomes da Silva","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:00 - 16:30","separator":true,"expanded":false,"cols":[{"title":"Poster Session and Coffee Break","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Stellar Physics","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:30 - 16:45","separator":false,"expanded":false,"cols":[{"title":"Brown dwarf formation across environments","bold":false,"expandable":true,"expanded":true,"content":"With masses below 0.08 Msun, brown dwarfs (BDs) are the link between stars and planets. Understanding their origin has been one of the major motivations for recent deep studies of star forming regions as well as a driver for development of state-of-the-art simulations. Deep surveys show that BDs are an ubiquitous outcome of star formation, with about 0.2-0.5 substellar objects formed for each star. One of the big questions in BD studies is whether the birth environment may affect their formation efficiency, as expected from several formation theories. The prediction is that high gas or stellar densities, as well as the presence of massive OB stars may be the factors that boost the frequencies of newly formed BDs with respect to stars. To test these predictions, we compare the outcome of our decade-long deep survey SONYC, in which we characterized substellar populations of several nearby star forming regions, with the results of our new search for substellar objects in massive young clusters RCW 38 and NGC 2244, characterized by drastically different star forming environments than those where BDs have been studied so far. In this contribution, I will present the current status of young BD studies, compare the low-mass Initial Mass Functions in a variety of Milky Way environments, and outline the impact of these results on our understanding of BD formation processes.","url":"","url_title":"Download"},{"title":"Koraljka Muzic","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:45 - 17:00","separator":false,"expanded":false,"cols":[{"title":"Youth indicators in near infrared spectra of brown dwarfs and very low mass stars","bold":false,"expandable":true,"expanded":true,"content":"Young clusters harbour a significant population of brown dwarfs (BDs). Comprehensive studies of these objects are necessary to answer some of the most important, and yet unanswered questions about their formation: How frequent are BDs compared to stars? Where is the low-mass limit of the Initial Mass Function (IMF)? Is the IMF universal? When searching for young brown dwarfs in stellar clusters, the main obstacle is the determination of cluster membership, which cannot be established by photometry only. Spectroscopic follow-up is an indispensable step to obtain robust samples of low-mass members. The brightness of these objects peaks in the near infrared (NIR), thus, it is crucial to have a robust method to analyze their NIR spectra, including the assessment of the object's youth. \n\nIn this contribution I will present a collection of NIR spectra of VLM objects. The spectral types can be derived with the help of existing and newly established spectral indices. I will present a method of assessing youth through comparison with spectral templates and indices, including a very promising newly discovered index based on the gravity-sensitive slope in the H-band. Finally, I will present our work in the 2 Myr old cluster NGC 2244, where we obtained ~140 spectra of candidate VLM objects, resulting in the first bona-fide BDs located at kpc distances.","url":"","url_title":"Download"},{"title":"Víctor Almendros-Abad","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:00 - 17:15","separator":false,"expanded":false,"cols":[{"title":"The relevance of partial ionization in the outer layers of F-stars","bold":false,"expandable":true,"expanded":true,"content":"The present-day quality of asteroseismic data allows us to probe the complex outer layers of sun-like stars. F-stars are particularly interesting given their diversity of magnetic and rotational behaviors. Using a seismic diagnostic based on the phase shift of the acoustic waves, we found a trend, in the form of a power-law dependence, that correlates the ionization processes occurring in these external layers with the rotation period of the stars. \nAdditionally, we have studied the internal structure of the outer layers of 10 main-sequence F-stars, and we found that the rotational characteristics of these stars can be distinguished by the relative location of the partial ionization region of heavy elements and the base of the convective zone. Since the region near the base of the convective zone (the tachocline) is know to have strong influence in the expected dynamo-driven mechanism, these results might be important to better and further understand the relations between magnetism and rotation in these stars.","url":"","url_title":"Download"},{"title":"Ana Brito","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:15 - 17:30","separator":false,"expanded":false,"cols":[{"title":"Stars and dark matter at the center of the Milky Way","bold":false,"expandable":true,"expanded":false,"content":"The study of dark matter captured inside stars has proved to be a viable indirect search strategy complementary to other direct searches. However, in this context, only a fraction of the rich diversity of physics found in different types of stars has been explored, with most studies mainly focused in the Sun. In this work we look instead to the center of the galaxy and study the imprint that a large number of dark matter particles can leave on two completely different types of stars: low mass main-sequence stars and horizontal branch helium burning stars. We found that the scattering interactions between baryons and dark matter particles within the central region of these stars can result in effects such as the slowdown of the nuclear burning rate or the suppression of core convection, both of which can have an important impact on the evolution and asteroseismology of the Star.","url":"","url_title":"Download"},{"title":"José Lopes","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:30 - 17:45","separator":false,"expanded":false,"cols":[{"title":"Derivation of fundamental stellar parameters for dwarf stars using spectral synthesis","bold":false,"expandable":true,"expanded":true,"content":"Stellar parameters of M dwarfs are important for many subfields of astronomy, and a uniform and accurate method for the derivation of their spectroscopic parameters from near-infrared spectra is still missing. \nIn this talk, I will show our method of spectral synthesis for the derivation of these parameters from H-band spectra of both FGK stars and M dwarfs, as well as the results obtained for a large sample of stars.","url":"","url_title":"Download"},{"title":"Pedro Sarmento","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:45 - 18:00","separator":false,"expanded":false,"cols":[{"title":"ODUSSEAS: A machine learning tool to derive effective temperature and metallicity for M dwarf stars","bold":false,"expandable":true,"expanded":true,"content":"Spectroscopic analysis is used to derive stellar atmospheric parameters such as effective temperature (Teff) and metallicity [Fe/H]. One of the most popular methods to derive them is by measuring the equivalent widths (EWs) of many metal lines of the spectrum. There are some difficulties that need to be overcome. One of the main problems is the correct determination of the spectral continuum, which is more problematic in cool and faint stars, such as M dwarfs. Their study is quite difficult and complicated, compared to FGK stars, since in M dwarfs, molecules are the dominant sources of opacity. These molecules create thousands of lines that are poorly known and moreover many of them blend with each other. Therefore, the position of the continuum is hardly identified in their spectra. Consequently, in our work, we make use of pseudo EWs of M dwarf spectra. \nWe present ODUSSEAS (Observing Dwarfs Using Stellar Spectroscopic Energy-Absorption Shapes): an automatic, easy-to-use, computational tool based on maching learning. ODUSSEAS uses the \"\"scikit-learn\"\" Python package and offers a quick derivation of Teff and [Fe/H] for M dwarf stars, by being provided with their 1D spectra and their resolutions. The main advantage of this tool, compared to other ones that derive stellar parameters such as MCAL code by Neves et al. 2014 (which works only for HARPS spectra), is that it can operate during the same run for spectra of different resolutions and different wavelength ranges in the optical. The tool is able to derive parameters with models of small precision errors ( ~30 K for Teff and ~0.02 dex for [Fe/H]), actual errors of ~110 K for Teff and ~0.09 dex for [Fe/H] including the intrinsic uncertainties of the reference parameters and consistent values for spectrographs with spectral resolutions between 48000 and 115000. \nWe show the structure of our tool and the flow of its process. We present the characteristics of its machine learning function and its efficiency regarding different resolutions and wavelength areas. We apply our tool to spectra obtained by several spectrographs of varying resolutions and we validate the reliability of our tool.","url":"","url_title":"Download"},{"title":"Alexandros Antoniadis-Karnavas","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]}]}

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{"title":"Day 2 - Friday, September 13","rows":[{"time":"09:00 - 10:00","separator":false,"expanded":false,"cols":[{"title":"The nature of the compact mass at the center of the Milky Way","bold":false,"expandable":true,"expanded":true,"content":"The compact and very massive object located at the center of the Milky Way is currently the very best candidate for a super-massive black hole (SMBH) in our immediate vicinity.  The strongest evidence for this is provided by measurements of stellar orbits, variable X-ray emission, and strongly variable polarized near-infrared emission from the location of the radio source Sagittarius~A* (SgrA*) in the middle of the central stellar cluster.  I will summarize and critically illuminate recent by observational results from the experiments like the Event Horizon Telescope (EHT) and infrared interferometry with GRAVITY at the Very Large Telescope Interferometer (VLTI).  In the light of the possibility of a charged black hole or charged source components I will elucidate on the question in how far these results actually support the presence of a super-massive black hole and fully reject alternative explanations.","url":"","url_title":"Download"},{"title":"Andreas Eckart","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Galactic Astronomy","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"10:00 - 10:15","separator":false,"expanded":false,"cols":[{"title":"A parameter study of tidal disruption events by Sgr A*","bold":false,"expandable":true,"expanded":true,"content":"Sgr A* is a super massive black hole (SMBH) that lurks in the centre of the Milky Way and affects the local stellar systems by capturing stars leading to their disruption through tidal effects. The thermal energy released during these tidal disruption events (TDEs) is responsible for X-ray emission observed with the XMM-Newton telescope, as well as the energising of the Fermi Bubbles. \nWe present the results of a parameter study of TDEs involving solar mass stars captured by Sgr A* and the amount of energy released during this phenomenon. The tidal disruption is evaluated in terms of the star trajectory with different penetration parameters (b) and the spatial distribution of the debris is tracked over time in order to determine the fraction of stellar mass that stays bound to the black hole.","url":"","url_title":"Download"},{"title":"João Rocha","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"10:15 - 10:30","separator":false,"expanded":false,"cols":[{"title":"The Orion luminosity/mass function revisited","bold":false,"expandable":true,"expanded":true,"content":"We present an analysis of the luminosity/mass function of the 15 largest groups (more than a hundred members each) identified towards the Orion Complex. Those groups were determined using spectroscopic and astrometric data from APOGEE-2 and Gaia DR2 by applying a hierarchical clustering algorithm to the six-dimensional stellar data. We used Gaussian mixture models to represent the sample, and have found luminosity/mass function sub-structures in most of the explored regions. We have tested our approach with the most recent member list of 25Ori as verification sample reproducing the found sub-structures in its luminosity/mass function. There is not a clear correlation with the regions estimated ages, although the most prominent structures dilute considering groups of groups. In this talk, I will discuss the possible structure origin regarding the applied mass estimate relations and if we could empirically calibrate pre-main sequence tracks by requiring groups to have consist ent mass functions.","url":"","url_title":"Download"},{"title":"Karla Peña Ramírez","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"10:30 - 10:45","separator":false,"expanded":false,"cols":[{"title":"Vector field reconstruction using integrated nested laplace approximations: unraveling stellar cluster kinematics","bold":false,"expandable":true,"expanded":true,"content":"Open clusters are fundamental probes of the structure and dynamics of the Milky Way, and of stellar structure and evolution. They may also offer a laboratory to study gravitational processes that may disrupt or disturb the motion of the stars within the cluster. In this project we adapted a statistical method to study the internal kinematics of Open Clusters from membership lists derived by the UPMASK method (Unsupervised Photometric Membership Assignment in Stellar Clusters) using the data from Gaia Data Release 2. We create a pipeline that adopts the Integrated Nested Laplace Approximation (INLA) method to reconstruct an approximation to the underlying, unobserved, proper motion vector field for all the observed stellar clusters considering the measurement errors. Based on the reconstructed maps, we analyze some objects to assess statistically relevant conclusions on the open clusters' internal kinematics.","url":"","url_title":"Download"},{"title":"Pedro Garcia","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"10:45 - 11:00","separator":false,"expanded":false,"cols":[{"title":"Understanding the galaxy evolution through spectral fitting tools: a comparative study of star formation history","bold":false,"expandable":true,"expanded":false,"content":"The extremely large telescopes commissioned for the next decade will open a new window in the comprehension of the formation and evolution of galaxies. In this context, important information about the physical processes involved will come from spectroscopy, since a spectrum contains crucial information about the stellar and gas emission, chemistry, and kinematics. Spectral analysis has shown to be reliable in many aspects and led to the discovery of important relations driving the galaxy evolution at different epochs. With the increase of technical capabilities different spectral analysis tools have been proposed to the scientific community in order to extract such parameters (STECKMAP, FireFly, FADO, VESPA and many others). But still, many biases and inconsistencies in the results are present, in some case leading to different results. The current state of the art of this technique suffers large uncertainties when leading with a relevant parameter driving the evolution of \ngalaxies: the star formation history. \n\nIn this presentation, a comparative study for some of these spectral fitting tools is performed, focusing on the discrepancies between the different approaches. Using the evolutionary stellar population code REBETIKO, a set of different mock spectra, with different SNR, and star formation histories are produced. These spectra are analyzed with three different tools: STARLIGHT, FADO and STECKMAP, to investigate at which SNR values each method is able to reproduce the input parameters. Each code uses a different method to extract the best fit, allowing the possibility to disentangle possible biases introduced in the analysis. \n\nSTECKMAP reproduces quite well the spectra and the star formation history of the mock data, even if for some particular model a secondary peak appears. This double peak is due to a bad spectral coverage within the time bin of the secondary peak since the proposed spectral synthesis population basis does not have a sufficient number of spectra covering that specific time bin. Moreover, we note that the typical double peak is on average shifted towards the younger or the older time bin. This introduces an interesting feature because the oldest time bin corresponds to a stellar population with high weight in terms of total mass and low weight in terms of total light, while the young one has a low weight in terms of mass but high weight in terms of light. This trend can have different origins: for example, these secondary peaks are particularly evident when considering stellar populations at an epoch where the nebular emission is still relevant. In those cases, FADO reproduces better the \ntrend for both nebular and stellar continuum emission, confirming that at these stages of star formation the nebular emission must be properly taken into account. \n\nWhere nebular emission is not negligible, the results obtained with methods taking into account such a component are more reliable, and this can be very important when moving at higher redshift, where the stellar populations are young. In particular, this is true for starburst systems, where a huge amount of stars are forming almost at the same epoch. This is an important aspect to take into account the future facilities, which will provide the community with high-resolution spectra of galaxies at redshift 3-4 and even higher. For these objects, it is important to quantify these effects, as the emission due to the ionized gas can be very high compared to the emission of the stellar continuum.","url":"","url_title":"Download"},{"title":"Ciro Pappalardo","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:00 - 11:30","separator":true,"expanded":false,"cols":[{"title":"Poster Session and Coffee Break","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Extragalactic Astronomy","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:30 - 11:45","separator":false,"expanded":false,"cols":[{"title":"First results from MUSE-Faint: MACHO constraints from a faint cluster in an ultra-faint dwarf galaxy","bold":false,"expandable":true,"expanded":true,"content":"We will present the first results from MUSE-Faint, a 100 hr MUSE GTO survey of ultra-faint dwarf galaxies around the Milky Way with the aim to understand better the early formation of these faint sources and to constrain the nature of dark matter. The focus in this talk is on Eridanus 2 which has a putative stellar cluster. Since ultra-faint dwarfs are strongly dark matter dominated, the surivial of this cluster can be used to constrain the abundance of MAssive Compact Halo Objects to dark matter. Using the unique capabilities MUSE we are able to, for the first time, demonstrate that the cluster is indeed real and place new and more robust constraints on the contribution of MACHOs to dark matter (Zoutendijk et al, submitted). We also show that if MACHOs make up a large fraction of dark matter they must have masses less than ~10 Msun.","url":"","url_title":"Download"},{"title":"Jarle Brinchmann","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"11:45 - 12:00","separator":false,"expanded":false,"cols":[{"title":"Breaking the wall: Seeking the earliest radio AGN within the EoR","bold":false,"expandable":true,"expanded":true,"content":"The existence of powerful AGN has now been established well within the first Gyr of the Universe, through the observations of tens of optically or near-infrared selected QSOs up to the currently highest redshift of z~7. Theoretical work has been developed showing how super-massive (M>10^9 Msun) black holes can exist at even earlier epochs, depending on a unknown but necessarily quick assembly and growth of a suitable seed. Some of these sources should be bright at radio wavelengths, and detectable well within the Epoch of Reionisation. These detections will be paramount to the understanding of the earliest stages of galaxy evolution but even more - they will allow the direct study of neutral hydrogen in the Epoch of Reionization, through SKA observations of the HI 21cm forest against such background radio sources. However, recent radio surveys have shown that, even if very high redshift radio AGN may have been already detected, their identification has proven all but impossible. Attempts to \"\"break this wall\"\" are on-going, but at a frustratingly slow pace. In order to focus the development of future SKA and SKA-pathfinder surveys we have initiated a systematic exploitation of state-of-the-art galaxy formation and evolution models in order to understand how the identification of EoR radio AGN can finally be achieved.","url":"","url_title":"Download"},{"title":"José Afonso","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:00 - 12:15","separator":false,"expanded":false,"cols":[{"title":"A search for galaxy building blocks behind massive clusters","bold":false,"expandable":true,"expanded":true,"content":"Massive galaxy clusters provide a natural solution of studying with high sensitivity and high spatial resolution the population of star-forming galaxies out to high redshifts (z>2). With the Hubble Frontier Fields program, we can now use accurate lensing models which allow for reliable estimation of galaxy structural parameters down to a resolution of a few tens of parsecs at these redshifts. By combining the latest lensing models and deep HST imaging data of the 6 observed clusters we measure both sizes and luminosities for a sample of ~3000 galaxies at 2<z<10. At the faintest luminosities (M_UV < -16) we find a population of galaxies with extremely small observed sizes (tens to hundreds of parsecs), which are comparable to those of large star-forming complexes in the local Universe. In my talk, I will provide the physical characterization of such population and detail their evolution from the peak of the star formation epoch to the epoch of reionization. I will then discuss the implications for the star formation in galaxies in the low-luminosity regime and provide estimates of the stellar mass budget of these sources. These galaxies are ideal sources for follow-up with JWST to provide observational constraints on the formation of galaxies at high-redshift.","url":"","url_title":"Download"},{"title":"Bruno Ribeiro","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:15 - 12:30","separator":false,"expanded":false,"cols":[{"title":"Structure of massive galaxies at z < 0.5","bold":false,"expandable":true,"expanded":false,"content":"The most massive (M_stellar >= 10^11 M_solar) galaxies in the local Universe are characterized by having a bulge-dominated morphology and old stellar populations, in addition to be confined to a tight mass-size relation. Identifying their main components can provide insights into their formation mechanisms and subsequent mass assembly. \nTaking advantage of HST CANDELS data, we analyze the lowest redshift (z < 0.5) massive galaxies in the H and I-band in order to disentangle their structural constituents and study possible faint non-axis-symmetric features. \nWe find that the Sérsic index does not offer a good proxy for the morphological type for our sample of massive galaxies. Our derived multi-component effective radii give a better description of the size of our sample galaxies than those inferred from single Sérsic models with GALFIT. Interestingly for our small albeit interesting sample, two of the late-type galaxies in our sample are by ~2 sigma smaller than expected from the local mass-size relation. For most of our sample galaxies, both single and multi-component Sérsic models with GALFIT show substantial systematic deviations from the observed surface brightness profiles in the outskirts. These residuals may be partly due to the stellar haloes of these objects or could arise from conceptual shortcomings of parametric 2D image decomposition tools. A problematic consequence is that they propagate into differences of >1 mag between model and observed radial I-H color profiles. This is a significant obstacle to the exploration of the structural evolution of galaxies that calls for a critical assessment and refinement of existing surface photometry techniques.","url":"","url_title":"Download"},{"title":"Sandra Reis","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:30 - 12:45","separator":false,"expanded":false,"cols":[{"title":"Optical rest-frame spectroscopy to study the filaments and galaxy clusters outskirts at z~1","bold":false,"expandable":true,"expanded":false,"content":"The VIMOS Spectroscopic Survey of a Supercluster in the COSMOS field (VIS3COS) aims to map in 3D accurately a superstructure at 0.8<z<0.9, which contains three massive X-rays confirmed clusters and shows a striking filamentary structure in the HiZELS Hα survey at z∼0.8 (Sobral et al. 2011). The ∼500 spectroscopic members probe a wide range of densities and environments (from fields to the cluster outskirts/rich groups). I will present this survey (PaulinoAfonso et al., 2018b) and our efforts to detail and understand the mass-environment relation, the nature of post-starburst galaxies, and the role of mergers (PaulinoAfonso et al., 2019a,b). Mass or environment: which plays the key role? Can we witness the transformation of the blue sequence into the red sequence? If so, where is it more prominent: in the filaments, groups, or clusters? Is this transformation also be encoded in the galaxy morphology? And what is happening to the interstellar medium pressure (or electron density)? Do we still have evidence for an environmental dependence of the electron density as reported by Darvish et al. (2015) at z∼1 and when we probe a wide range of overdensities and different mass regimes?","url":"","url_title":"Download"},{"title":"Ana Paulino-Afonso","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"12:45 - 13:00","separator":false,"expanded":false,"cols":[{"title":"Strongly-lensed quasars: where astrometry, meets entropy, wavelets and machine-learning","bold":false,"expandable":true,"expanded":false,"content":"The 'Gaia Gravitational Lenses' group (GraL) was created to systematically identify and characterize gravitational lenses in the form of multiply imaged quasars from the data releases of the ESA/Gaia satellite. Owing to its exceptional angular resolution and very accurate photometry, Gaia is expected to observe thousands of gravitational lenses, among which $\\sim$250 should be quadruply imaged. For the first time a survey of such phenomena over the entire sky is possible, and this will result into an invaluable dataset particularly well-suited for extragalactic and cosmological studies, and to derive relevant constraints on Dark Matter properties and the Hubble constant. In this short communication we will quickly present some of the strategies that the GraL group created and is adopting to search for new multiply-imaged Quasars in Gaia and beyond. These techniques are based on astrometry, time-series and imaging, and in the adoption of supervised and unsupervised machine learning methods. We will also show a few lenses discovered and confirmed in the first year of our lens search, including the first ever gravitational lens first discovered from astrometry alone.","url":"","url_title":"Download"},{"title":"Alberto Krone-Martins","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"13:00 - 14:30","separator":true,"expanded":false,"cols":[{"title":"Lunch","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Cosmology","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"14:30 - 14:45","separator":false,"expanded":false,"cols":[{"title":"Low redshift constraints on energy-momentum-powered gravity models","bold":false,"expandable":true,"expanded":true,"content":"There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations is modified by the addition of a term proportional to some power, n, of the energy-momentum tensor, in addition to the canonical linear term. In this work we treat these models as phenomenological extensions of the standard ΛCDM, containing both matter and a cosmological constant. We also quantitatively constrain the additional model parameters using low redshift background cosmology data that are specifically from Type Ia supernovas and Hubble parameter measurements. We start by studying specific cases of these models with fixed values of n, which lead to an analytic expression for the Friedmann equation; we discuss both their current constraints and how the models may be further constrained by future observations of Type Ia supernovas for WFIRST complemented by measurements of the redshift drift by the ELT. We then consider and constrain a more extended parameter space, allowing n to be a free parameter and considering scenarios with and without a cosmological constant. These models do not solve the cosmological constant problem per se. Nonetheless these models can phenomenologically lead to a recent accelerating universe without a cosmological constant at the cost of having a preferred matter density of around Ω_M ∼ 0.4 instead of the usual Ω_M ∼ 0.3. Finally we also briefly constrain scenarios without a cosmological constant, where the single component has a constant equation of state which needs not be that of matter; we provide an illustrative comparison of this model with a more standard dynamical dark energy model with a constant equation of state.","url":"","url_title":"Download"},{"title":"Maria Faria","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"14:45 - 15:00","separator":false,"expanded":false,"cols":[{"title":"Phenomenology of a scaling cubic galileon model","bold":false,"expandable":true,"expanded":true,"content":"Due to the shortcomings the Lambda-cold-dark-matter (LCDM) model still faces, modified gravity (MG) models have been widely explored as an alternative explanation for the late-time accelerated expansion of the Universe. In this talk I will present a Cubic Horndeski model, dubbed the Scaling Cubic Galileon, capable of reproducing a late-time acceleration period as well as introducing new scaling solutions in the presence of cubic Horndeski interactions and a standard scalar-field kinetic term with two exponential potentials. In addition to an exploration of its background dynamics, I will also show a study of the model’s effect on large-scale structure observables, such as the matter and Cosmic Microwave Background (CMB) temperature and lensing power spectra, performed using the Einstein-Boltzmann code EFTCAMB.","url":"","url_title":"Download"},{"title":"Inês Albuquerque","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:00 - 15:15","separator":false,"expanded":false,"cols":[{"title":"Testing unified dark matter-energy models against structure formation","bold":false,"expandable":true,"expanded":false,"content":"In this talk I will present the results of testing two types of UDM models: The generalized Chaplygin gas with a back-reaction effect and an UDM model with fast transition. Implemented in the Boltzmann code CLASS we test these models against weak lensing, CMB, SNe IA and BAO tests. In the second case, due to a unsmooth matter power spectrum caused by a speed of sound bigger than zero, the traditional sampling methods used in MCMC codes known as annealing methods, like Metropolis-Hastings, are not very efficient, resulting in long computation time and hard fine tuning of parameters. In this talk, I will present the results comparison obtained when using this sampling algorithm and a Nested Sampling algorithm, explain the second method and why it is considerably better. Then I will show the results of model comparison against ΛCDM and enumerate some topics in the line of work for UDM models to be tested with Euclid future data.","url":"","url_title":"Download"},{"title":"Diogo Castelão","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:15 - 15:30","separator":false,"expanded":false,"cols":[{"title":"Consistency of local and astrophysical tests of the stability of fundamental constants","bold":false,"expandable":true,"expanded":true,"content":"Tests of the stability of nature’s fundamental constants are one of the cornerstones of the ongoing search for the new physics which is required to explain the recent acceleration of the universe. The two main settings for these tests are high-resolution spectroscopy of astrophysical systems (mainly in low-density absorption clouds along the line of sight of bright quasars) and laboratory comparisons of pairs of atomic clocks. Here we use standard chi-square techniques to perform a global analysis of all currently available data, studying both the consistency of tests of stability of different constants (specifically the fine-structure constant α, the proton-to-electron mass ratio μ and the proton gyromagnetic ratio gp) and the consistency between local laboratory and astrophysical tests. We start by doing a model-independent analysis (studying the internal consistency of the various available datasets) but also explore specific phenomenological models motivated by string theory and grand unification. Overall there is weak (one to two sigma) evidence of variations, at the level of up to a few parts per million, and reasonable agreement between laboratory and astrophysical tests. This result holds even if one removes from the analysis the Webb et al. archival dataset of α measurements. Forthcoming astrophysical facilities, such as the ESPRESSO spectrograph, should be able to confirm or rule out these hints. This work has been recently published at Phys.Dark Univ. 25 (2019) 100301.","url":"","url_title":"Download"},{"title":"Meritxell Vila Miñana","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:30 - 15:45","separator":false,"expanded":false,"cols":[{"title":"Coupled quintessence with a ΛCDM background","bold":false,"expandable":true,"expanded":true,"content":"We look at models of coupled quintessence with a ΛCDM background. Differences with the standard concordance model only appear at the perturbative level. We show that the coupled model can remove the observed σ_8 tension in redshift space distortion data. We also use a spherical collapse model to estimate how future cluster number counts can be used to distinguish between the two scenarios.","url":"","url_title":"Download"},{"title":"Tiago Barreiro","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"15:45 - 16:00","separator":false,"expanded":false,"cols":[{"title":"A cosmological stabilization mechanism of the sign of the gravitational constant","bold":false,"expandable":true,"expanded":true,"content":"In this work, we investigate a cosmological mechanism that may define the sign of the effective gravitational coupling constant, G. To this end, we consider general scalar-tensor gravity theories as they provide the natural framework in filed theory for the variation of the gravitational coupling. We find that models with a quadratic potential naturally stabilise the value of G into the positive branch of the evolution and further, that de Sitter inflation and a relaxation to General Relativity is simultaneously attained.","url":"","url_title":"Download"},{"title":"José Mimoso","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:00 - 16:30","separator":true,"expanded":false,"cols":[{"title":"Poster Session and Coffee Break","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Astronomical Instrumentation","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:30 - 16:45","separator":false,"expanded":false,"cols":[{"title":"ESPRESSO: a high-resolution spectrograph at the 4 ESO’s VLT telescopes","bold":false,"expandable":true,"expanded":true,"content":"ESPRESSO is a fibre-fed, cross-dispersed, high-resolution, echelle spectrograph developed to fully exploit the European Southern Observatory VLT (Very Large Telescope), and it was open to the astronomical community at the end of 2018. \nThis spectrograph was installed at the Combined Coudé Laboratory (CCL) of the VLT, fed by four Coudé Trains, which bring the light to the CCL from the Nasmyth platforms of the four 8.2-metre Unit Telescopes. \nWith all four Telescopes combining their light-collecting power to feed a single instrument, the ESPRESSO Coudé Train effectively transforms the VLT into the largest optical telescope in the world in terms of collecting area. \nThe Coudé Train allows the spectrograph to either collect the light from up to all four Unit Telescopes together, or alternatively receive light from any one of the telescopes independently, allowing for more flexible usage of observing time. \nIn this talk we present the ESPRESSO spectrograph and the Coudé Train subsystem that was implemented by a Portuguese Team.","url":"","url_title":"Download"},{"title":"Alexandre Cabral","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"16:45 - 17:00","separator":false,"expanded":false,"cols":[{"title":"The Southern Wide field-of-view Gamma-ray Observatory","bold":false,"expandable":true,"expanded":true,"content":"Very-high-energy gamma-rays are linked to high-energy phenomena in the Universe. The Southern Wide eld-of-view Gamma-ray Observatory (SWGO) is a newly formed international collaboration to design and build a new observatory to be placed in the Andes at an altitude of around 5000 m. This observatory, being at the Southern hemisphere, would be able to monitor the galactic center, search for transient events, explore very extended emission regions and alert/follow-up on neutrino and gravitational wave detections as well as other photon observatories. SWGO is entirely complementary to the planned Cherenkov Telescope Array (CTA) that will be able to scrutiny astrophysical sources with unprecedented sensitivity. CTA has a limited field-of-view and low duty cycle which undermines its capabilities to observe transient phenomena such as Gamma-Ray Burst or ares from Active Galactic Nuclei. In this presentation, I shall briefly discuss the physics potential of SWGO and the R&D options being explored to detect gamma-ray in a broad energy range (from 100 GeV to 100 TeV).","url":"","url_title":"Download"},{"title":"Ruben Conceição","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:00 - 17:15","separator":false,"expanded":false,"cols":[{"title":"Development of sparse coding and reconstruction subsystems","bold":false,"expandable":true,"expanded":false,"content":"Compressed sensing (CS) is a revolutionary signal processing technique that allows us, under a  specific set of conditions, to fully reconstruct an under- sampled signal. Very early, from  its inception, in 2006, to subsequent development and propagation in the following years  compressed sensing enabled advancements in photography, holography and medical  instrumentation among others. Its application in astronomy however,  even though some calls to action have recently been made, has failed to leave the test bed.\n\nContinuing from the works of Bandarra and Pires, advancements will here be  described on the development of a physical, out of the table, instrument; a compressed sensing  astronomy camera (COSAC). Such an instrument was projected to be constituted by five  subsystems: optomechanics, signal coding, acquisition electronics, signal  reconstruction and the mechanical structure (casing and inner supports for the  aforementioned subsystems). The present work focused on the development/implementation of signal coding  and reconstruction subsystems, while a simple prototype for the mechanical structure is also  proposed to enable testing the instrument in a real world setting; this required the redesign of  the optomechanical supports. Additionally, some changes were made to the acquisition  electronics in order to not only improve its behavior, but to also facilitate its integration with  the signal coding subsystem; as a result two working circuit are proposed, one using an ADC of  10 bits resolution, the other an ADC of 24 bits.\n\nA central component to this instrument, which bridges the optomechanics, signal coding and  acquisition subsystems, is a digital micromirror device (DMD), an array of independently  controlled micromirrors which can be tilted in two, opposed, directions. Such a device can, and  is, thus used to manipulate light. For this project a DLP LightCrafter, a projector development  kit by Texas Instruments which includes a DMD, was used to encode light signals.\n\nThe signal coding subsystem is constituted by the LightCrafter and two programs: one  written in C/C++ to run either on a PC (DMD-CS.cpp), which main purpose is to control  the DMD and communicate with the LightCrafter’s processor, and which also communicates  with an Arduino micro-controller that manages the acquisition electronics; the second (which  is also part of the acquisition subsystem) in Arduino programming language, to run on the  micro-controller (pIDDO.ino), which will manage the processes required to perform measurements  with the electronics and communicate with the C/C++ program; the interactions between both programs are crucial to ensure synchronism between the signal coding and acquisition subsystems.\n\nThe chosen encoding basis are squared Hadamard matrices that can be attained by  following simple algorithms; rows of such matrices were then manipulated into tilt  configurations for the micromirror grid; the set of rows used will constitute a sampling matrix.  Each program outputs a file, one holding information about the sampling matrix used, the  other holding the measurements.\n\nThe signal reconstruction subsystem is another  program that takes the files generated by  DMD-CS.cpp and pIDDO.ino to reconstruct the original signal by implementing a Matlab script  written by Romberg. The program then outputs a BMP image file of that reconstruction.\n\nThe components of the prototype structural subsystem and optomechanical supports were  designed using computer assisted design (CAD) software, with which finite element simulations  were also performed to ensure those same components would be able to endure real world  conditions. Some of these components were bought most of them were fabricated in the  laboratory.\n\nAll subsystems were individually tested, as well as in couples (when relevant). After passing  those tests, these subsystems were assembled to form COSAC. The instrument was calibrated,  analysed and validated, using both versions of the acquisition circuit, in a laboratory setting with  controlled lighting conditions. Comparative results of COSAC’s performance for three modes of  acquisition (raster, Hadamard transform optics and CS with Hadamard base) are also presented.\n\nCOSAC was shown to be able to produce images of CS measurements, performed in the  visible spectrum, with at least 64×64 pixels.","url":"","url_title":"Download"},{"title":"João Silvestre","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:15 - 17:30","separator":false,"expanded":false,"cols":[{"title":"Atmospheric dispersion correction: Residuals requirements","bold":false,"expandable":true,"expanded":false,"content":"Observations with ground based telescopes are affected by differential atmospheric dispersion, a consequence of the wavelength-dependent index of refraction of the atmosphere and the angle of observation. One of the instrumental sources of errors in astronomical observations is due to atmospheric dispersion. Therefore, an atmospheric dispersion corrector (ADC) is needed. With the arrival of large telescopes, and the need for high resolution spectrographs to reach an RV precision ∼10 cm/s, stringent instrumental requirements are needed. In this talk, we will attempt to investigate the effects of atmospheric dispersion in order to quantify the amount of ADC residuals needed. By doing this, we will be able to justify the requirements on the ADCs from an instrumental and astrophysical perspective.","url":"","url_title":"Download"},{"title":"Bachar Wehbe","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:30 - 17:45","separator":false,"expanded":true,"cols":[{"title":"Manuel Abreu","bold":false,"expandable":false,"expanded":false,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":false,"expanded":false,"cols":[{"title":"Outreach in Astronomy","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"17:45 - 18:00","separator":false,"expanded":true,"cols":[{"title":"Eddington @ Sundy: 100 years later","bold":false,"expandable":true,"expanded":true,"content":"Eddington @ Sundy celebrates the 100th anniversary of the 1919 solar eclipse. This project, organized by Santomean and Portuguese institutions, which results from a five-year record of collaboration and cooperation, is promoting initiatives on a global scale, but also with the goal of being a cornerstone to create a historic and scientific legacy in São Tomé and Príncipe, especially at Roça Sundy, the place where the observations were made. Based on a concerted programme oriented for Science, History of Science, Science Education and Science Outreach, we aim that the Santomean population gradually takes ownership and that the international community gets involved. In this presentation, a brief overview of the project will be presented. We will also focus on the collaboration and articulation between more than 50 entities, as well as to highlight the impact of the international event on the last week of May 2019 on the island of Príncipe. More information at: esundy.org.","url":"","url_title":"Download"},{"title":"Joana Latas","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"18:00 - 18:15","separator":false,"expanded":true,"cols":[{"title":"The light deflection measurements of 1919","bold":false,"expandable":true,"expanded":true,"content":"As a contribution to the celebration of the 100 years of gravitational light deflection, I revisit the measurements made by the solar eclipse expedition of 1919 to Principe and Sobral. I discuss the self-calibration method of Sobral and the external-calibration method of Principe, and present a new Fisher matrix analysis of the published results.","url":"","url_title":"Download"},{"title":"Ismael Tereno","bold":false,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]},{"time":"","separator":true,"expanded":true,"cols":[{"title":"Closing Session","bold":true,"expandable":false,"expanded":true,"content":"Expandable Content","url":"","url_title":"Download"}]}]}

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