O programa de estágios de verão IAstro 2021 irá decorrer entre 12 e 30 de julho.
Neste programa, estudantes do ensino universitário tomam contacto com a investigação e a comunicação de ciência no Instituto de Astrofísica e Ciências do Espaço (IA). Desenvolvem projetos de investigação ou de comunicação de ciência, com o acompanhamento de investigadores do IA e da Faculdade de Ciências da Universidade de Lisboa ou Universidade do Porto. O programa inclui também seis workshops de comunicação de ciência. No último dia são apresentados os trabalhos realizados.
Devido à atual pandemia de Covid-19, os estágios decorrerão em formato remoto, com acompanhamento online dos investigadores, em horário a combinar, e sessões síncronas participativas.
As candidaturas estão abertas até 13 de junho. Os interessados deverão enviar:
- carta de motivação;
- CV (máximo de três páginas);
- listagem das cadeiras feitas e respetivas notas;
- três opções de entre os projetos disponíveis, por ordem de preferência (ver lista e descrição de projetos em baixo).
Email para envio da candidatura: email@example.com (até 13 de junho). Os resultados serão anunciados até 21 de junho.
- Black hole shadows and photon rings
- Wormholes in spacetime and their use for interstellar travel: a tool for teaching general relativity
- Exploring the impact of modifications of gravity law on cosmological observables
- The Cosmic Microwave Background radiation: a phenomenological study
- Testar a lei da aceleração do Universo
- Como simular todo o Universo num computador?
- Cosmologia com galáxias: padrões de tesselação e vazios cósmicos
- Cosmic strings as a window to the early universe
- Galactic winds in starburst galaxies
- The 200: exploring the most active supermassive black holes in the first Gyr of the Universe
- MOSDEF: nebular emission in COSMOS
- Paving the road of the Athena/WFI X-ray mission with simulations
- Identifying and characterizing AGN in next-generation radio surveys using machine and deep learning
- Giant hub-filament systems
- Asteroseismology: an exploratory tour of the oscillations in red giant stars
- Finding the best way to model stellar activity noise with the hydrogen line
- Rotation of stars with planets: combining ESPRESSO with TESS
- Binary twin stars with significantly different compositions
- Studying the atmospheres of other worlds within and outside the Solar System
- Fora da caixa: como motivar para a ciência?
Workshops de comunicação de ciência
- Comunicar ciência p’ra quê?
- Exercícios de aquecimento de voz e corpo
- Estrutura e design numa apresentação ou poster
- Escrever sobre ciência sem ser chato
- Falar em público: corpo, voz e mensagem
- Falar em público: o improviso
Descrição dos projetos
Orientação: Francisco Lobo – IA e Ciências ULisboa
Número máximo de estudantes: 5 (possível extensão após avaliação)
The Event Horizon Telescope (EHT) collaboration recently reported the first observation of a supermassive black hole, at the centre of the nearby galaxy M87. In this project, the students will acquire the mathematical tools and the physical intuition to describe this amazing observation, in an elementary manner. More specifically, the presence of a bright “photon ring” surrounding a dark “black hole shadow” has been discussed as an important feature of the observational appearance of emission originating near a black hole. We clarify the meaning and relevance of these heuristics with analytic calculations and numerical toy models. The standard usage of the term “shadow” describes the appearance of a black hole illuminated from all directions, including from behind the observer. A photon ring results from light rays that orbit around the black hole in the near field region before escaping to infinity. We also aim to build a bridge to state-of-the-art research where several shadows of alternative compact objects are studied and compared to black holes.
Wormholes in spacetime and their use for interstellar travel: a tool for teaching general relativity
Orientação: Francisco Lobo – IA e Ciências ULisboa
Número máximo de estudantes: 5 (possível extensão após avaliação)
Rapid interstellar travel by means of spacetime wormholes is described in a way that is useful for teaching elementary General Relativity (GR). Many objections are given against the use of black holes or Schwarzschild wormholes for rapid interstellar travel. A new class of solutions of the Einstein field equations is presented, which describe wormholes that, in principle, could be traversed by human beings. It is essential in these solutions that the wormhole possesses a throat at which there is no horizon; and this property, together with the Einstein field equations, places an extreme constraint on the material that generates the wormhole’s spacetime curvature. This material violates all the ‘‘energy conditions’’ that underlie some deeply cherished theorems in GR. However, it is not possible today to rule out firmly the existence of such material; and quantum field theory gives tantalizing hints that such material might, in fact, be possible. In this project, the students will study and solve the static and spherically symmetric Einstein field equations, with applications to traversable wormhole geometries, with the fundamental motivation in being an ideal tool for learning the basics of Einstein’s GR.
Orientação: Noemi Frusciante – IA e Ciências ULisboa
Número máximo de estudantes: 2
A problem faced by modern cosmology concerns cosmic acceleration, i.e. the phase of accelerated expansion recently entered by the Universe, for which we still lack a satisfactory theoretical explanation. A plethora of models addressing this phenomenon has been proposed and analyzed. Moreover, the ability to constrain various properties of cosmological models using observational data such as the anisotropies of the cosmic microwave background, the large scale structure of the galaxy distribution, the expansion and acceleration rate of the universe and other such quantities, has become an essential part of modern cosmology. A crucial aspect of this endeavour is to be able to accurately calculate a range of observables from the cosmological models. This is done with Einstein-Boltzmann EBo solvers, i.e. codes that solve the linearized Einstein and Boltzmann equations on an expanding background. A popular EB code is CAMB which was developed to accurately model the standard cosmology, i.e. General Relativity with a cosmological constant. Recently, an extension of CAMB, dubbed EFTCAMB, has been developed with the purpose of testing a broad class of modified gravity theories. In this project, the student will study the basis of linear cosmological theory of gravity with application to modified gravity. He/she will be familiar with EB code, EFTCAMB and will investigate the deviations from the standard cosmological model of a specific modified gravity model.
Orientação: Noemi Frusciante – IA e Ciências ULisboa
Número máximo de estudantes: 2
The cosmic microwave background (CMB) is the furthest back in time we can explore using light. It formed about 380,000 years after the Big Bang and imprinted on it are traces of the seeds from which the stars and galaxies we can see today eventually formed. Hidden in the pattern of the radiation is a complex story that helps scientists to understand the history of the Universe both before and after the CMB was released. Any theoretical model which aims at explaining the evolution of the Universe is characterized by a given number of parameters. Different values of these parameters produce a different distribution of structures in the Universe, and a different corresponding pattern of fluctuations in the CMB. Thus CMB can help astronomers extract the parameters that describe the state of the Universe soon after it formed and how it evolved over billions of years. In this project, the student will investigate the impact of cosmological parameters on the CMB. The project is divided in two steps: firstly the student will get in touch with the phenomenology associated with the CMB, then a hands-on part will follow, where the student will reproduce the CMB cosmological observables.
Neste projeto, o aluno toma contacto com dados observacionais da magnitude de supernovas Ia com o objetivo de se entender a natureza da aceleração do Universo. Este trabalho usa como ferramenta principal técnicas de regressão simbólica em que se testa a lei da taxa de expansão do Universo sem hipóteses teóricas iniciais.
Orientação: António da Silva – IA e Ciências ULisboa
Número máximo de estudantes: 2
Simulações numéricas de N-corpos permitem simular toda a evolução do Universo com recurso a métodos avançados de computação. Os participantes desta actividade vão aprender a gerar simulações cosmológicas com o código Gadget, e a analisar os resultados dessas simulações com recurso a software de visualização e de cálculo de grandezas características da distribuição de estruturas (enxames de galáxias, filamentos e vazios cósmicos) que se formam nos volumes simulados.
Esta atividade propõe aos participantes estudar as propriedades dos grandes vazios cósmicos e dos padrões de distribuição de galáxias e enxames de galáxias, por forma a pôr em evidência a dependência dessas propriedades com o modelo cosmológico e o processo de formação e evolução de estrutura de larga escala no Universo. Os alunos trabalharão com modelos matemáticos e simulações da distribuição de galáxias que são utilizadas pelo grupo de cosmologia em estudos relacionados com a missão espacial Euclid.
Orientação: Ivan Rybak – IA e UPorto
Número máximo de alunos: 2
Cosmos provides us access to unique conditions under which we can inspect our understanding of fundamental physics. The fascinating period for this purpose was an early stage of the Universe when it had an extremely high temperature and density, thus an environment with high energy. This stage of the Universe evolution occurred billions of years ago, making it challenging to explore. However, there is a phenomenon that might be helpful for our access to some high energy scenarios: cosmic strings, known as one dimensional topological defects. Once cosmic strings appear during the early Universe phase transition, they continue to exist somewhere in the Universe until the current time, sending signals that allow us to have information about what happened in the high energy epoch. In this project, we will learn what a cosmic string is by understanding the basic concepts of symmetry breaking. We will study some types of signals that come from these objects. The student will work on a particular example of an observational outcome from cosmic strings and get some intuition about the Universe in which topological defects are present.
Orientação: Polychronis Papaderos – IA e Ciências ULisboa
Número máximo de estudantes: 2
A thorough understanding of the physical processes that shape the evolution of galaxies requires spatially resolved spectroscopic information over the entire galaxy’s extent. Most spectroscopic studies carried out so far use data taken within a small aperture that typically covers only the central part of a galaxy. This strongly limits our understanding on galaxy evolution and potentially leads to significant observational biases. Recently, with the advent of modern Integral Field Spectroscopy (IFS) units, detailed 2D studies of galaxies over a wide field of view became possible. For instance, the Multi Unit Spectroscopic Explorer (MUSE) IFS unit at the Very Large Telescope of the European Southern Observatory records 90000 spectra in a single observation, this way permitting an unprecedentedly detailed view of the stellar and ionized gas component in galaxies. Researchers at the Instituto de Astrofísica e Ciências do Espaço (IA) have developed a suite of advanced tools for the processing and modeling of IFS data, which they intensively apply to studies both of evolved nearby galaxies and young galaxies in the early Universe. The project proposed here will focus on the analysis of IFS data for a small sample of starburst galaxies. These systems exhibit strong star-forming activity that results in the formation of thousands-to-millions of massive stars within a brief active phase of a few 10 Myr. The vigorous energy release from multiple supernova explosions occurring during such a starburst episode leads to fast ionized gas outflows with velocities of several 100 km/s. The student(s) will be given the opportunity to study the morphology, kinematics and physical properties (e.g., electron density) of such starburst-driven galactic winds using high-quality data with MUSE and other IFS units.
Orientação: José Afonso – IA e Ciências ULisboa
Número máximo de estudantes: 2
Over the last few years we have been able to detect, and start exploring, more than 200 quasars in the first Gyr of the Universe’s History. Often selected at optical and near-infrared wavelengths, it is now possible to study these early extreme sources using radio observations, which will provide fundamental indications for the understanding of the first stages of galaxy formation.
The main challenge of Astrophysics in the last decade has been the construction of a complete picture of galaxies evolution. To fully model the observations, it is necessary to include in a consistent framework all the physical processes responsible for the emission observed. As an example, the contribution due to the nebular emission, i.e. the ionized gas surrounding the star-forming regions, can be very large in star-forming galaxies. However, despite this possibility, most of the code to interpret the spectrum of a galaxy is “purely stellar”, assuming a negligible fraction of nebular emission. The University of Porto developed recently a tool for the interpretation of a spectrum in terms of a combination of stellar and nebular emission, FADO. The first tests, applied to the sample of nearby galaxies in SDSS, have shown promising results, allowing now the possibility to investigate the evolutionary trends of the stellar and nebular relative contribution to the total emission at younger epochs. The goal of this project will be to investigate such components in higher redshift galaxies, taking into account the MOSFIRE Deep Evolution Field (MOSDEF) survey, a program to observe the stellar, gaseous, metal, dust, and black hole content of ~1500 galaxies when the Universe was 1.5 to 4.5 billion years old. One of the fields observed with MOSDEF is COSMOS, and this dataset has been recently released to be investigated by the scientific community. With such data and applying the FADO analysis tool developed in Porto, the project will tackle the debated problem of the evolution of stellar and nebular emission at different galaxies epochs.
Supermassive Black Holes (M● > 1e6 M๏; SMBH) are probably present at the center of most galaxies. The growth of such massive objects occurs during episodic accretion phases of gas – liberating in the process large amounts of energy that in many cases outshine the light of all stars in the host galaxy – and that can greatly influence its evolution. SMBH in such phases are called Active Galactic Nuclei (AGN) and might have a predominant role in theories for galaxy evolution. The precise mechanisms of their influence at the different stages of galaxy evolution are still debated by the scientific community. A primary step to fully understand such a role is to obtain the most complete census of SMBH and AGN across cosmic time. We know that AGN could be predominantly detected thanks to their unique X-ray emission. For this reason, the future ESA mission ATHENA – a space telescope with the capability to focus X-ray photons – aims to answer these and many other questions related to the high energetic Universe thanks to the significant improvements over its predecessors: XMM-Newton and Chandra. Athena is expected to launch into an L2 orbit in the early 2030s and will reach, by the end of 2022, the mission adoption stage. The telescope and its instruments are now in a defining stage that will specify its final characteristics (e.g. sensitivity, resolution, etc) and the scientific goals to be reached. The IA is significantly involved in the WFI instrument with strong participation in the instrument simulations. At this stage it is critical to be able to simulate the most representative X-ray sky to be seen by Athena, as the type and number of sources to be detected will significantly impact the achievement of the WFI mission key goals. Some goals that the students will explore are: I. derive a catalog of X-ray sources based on the expectations of the most recent cosmological simulations recently published by the IA AGN group, II. using the SIXTE X-ray telescope simulator for ATHENA/WFI, estimate the minimum observing time and strategy necessary to achieve the fundamental goals of the mission, III. investigate the impact of source confusion and source detection on the final specifications of the mirrors + instrument. During this internship, the student will acquire a basic understanding of extragalactic sources of X-ray emission (AGN, galaxies, and clusters of galaxies), and the basic use of an X-ray telescope simulator, participating in a critical stage of the Athena mission implementation and characterization. She/he will also be introduced to key concepts of an X-ray telescope’s development, design, and general properties.
Supermassive Black Holes (SMBH) are ubiquitous to all spheroidal galaxies and the bulges of late-type galaxies. The tight connection between the properties of bulges and spheroids (e.g. velocity dispersion, luminosity) and those of the SMBH (e.g. mass) suggests a co-evolution between the two along cosmic time. Although how this connection formed and evolved with time is currently one of the big uncertainties in our models for the evolution of galaxies and structures in the Universe, we know this most probably happened during the growth period of the SMBH through accretion phases (AGN phase). The identification and characterization of the largest number of AGN are paramount to understand their precise role in galaxy evolution. We know that AGN could be easily detected thanks to their unique jet emission in the radio. In fact, nowadays, the next-generation of radio observatories (e.g. MeerKat, ASKAP and LOFAR) are starting to produce catalogs of radio sources which are one or two orders of magnitude bigger than any previous dataset. Many of these new observatories are part of the so-called Square Kilometer Array (SKA) pathfinders with the goal of optimizing observation strategies and analysis techniques of the future full SKA (mid-2020s). When fully functional, SKA promises even deeper and more sensitive observations over the entire southern hemisphere sky at unprecedented data rates. The precise characterization of radio-AGN can only be done with spectroscopic observations as they provide detailed insight into the composition, structure, and physical processes at work as a function of cosmological time. Unfortunately, they also require significant allocation of telescope time and only about 10% of extragalactic sources have spectra. This has not prevented the scientific community, over the last 20 years, to gather an impressive compilation of spectroscopic observations of galaxies and AGN, reaching almost 1e6 spectra from the later one. Given the amount of detections of the SKA precursors and later on by the SKA itself, the spectroscopic follow-up will lag behind for many years to come. To overcome this handicap, the use of the already available spectral information (for ~500 000 AGN) and novel machine and deep learning techniques, could help identify and understand the nature of the radio sources detected. It might be possible to retrieve estimates of distances (redshift), morphological and intrinsic properties and classify them according to these properties. We propose in this internship a machine and deep learning analysis of a set of many millions of sources detected in the most recent radio surveys (e.g. RACS and LoTSS).
The cold and dense gas in the interstellar medium (ISM) is filamentary in nature. In a dynamical evolving ISM, which is subject to shock waves from supernovae, feedback effects, filaments are moving constantly and when they criss-cross each other they form junctions called hubs. For the first time, our group showed that star clusters and very massive stars preferentially form in such hub-filament systems. The Herschel Space Telescope has mapped the majority of the Milky-Way disk plane in five far-infrared bands. There are about 144 targets which are so bright that the central parts of those images are saturated. We have found that all these saturated sources represent hub-filament systems after remodeling and fixing those patches. This project involves using these 144 targets and producing a catalog of giant hub-filament systems using dust surface density maps and images. The project will involve looking at the images, analyzing them in some simple ways and producing some spectacular color images of giant hub-filament systems. If the student is familiar with python programming, additionally a small recipe to produce surface density maps using the Herschel space telescope data can be coded.
Asteroseismology is a research field dedicated to the exploitation of the natural pulsation of stars. By the study of these pulsations, this science has given us an unprecedented way to investigate how the stars are made inside. Important breakthroughs in stellar astrophysics have been made in the last decade with the advent of ultra-high precision photometry, as the results of space missions like CoRoT (ESA), Kepler (NASA), and TESS (NASA) that allowed us to detect oscillations in tens of thousands of stars. However, the variation along the star evolution of the oscillatory patterns is still not fully explored and may contain important information that can help us to distinguish different phases. The project is dedicated to the exploration of the small separations in red-giant stars, a quantity that comes from the analysis of the oscillation spectra of the stars. This quantity contains important signatures of the internal structure of the stars. The analysis will be done by looking and comparing models of red giant stars and observations of real stars, with the aim of understanding the behaviour of this still poorly-studied quantity.
One of the most used techniques to detect exoplanets is the Doppler spectroscopy, also known as radial velocity (RV) method. This method consists of measuring the RV (the velocity projected in the observer’s line-of-sight) of a star to detect the very small periodic variations caused by an orbiting planet. However, stellar intrinsic phenomena can affect the measured RV. Zones with strong magnetic fields in the stellar disk are associated with active regions, which include dark spots and/or bright faculae. These regions, as the star rotates, will appear and disappear from sight, producing a modulation in the observed RV that can difficult or mimic the detection of low-mass planets. There are several spectroscopic indices used to detect those variations of stellar origin including, for example, the ones based on the activity sensitive CaII H&K and Halpha spectral lines. In this project, the student will study the effect of using different bandpasses to measure the Halpha line index. The results of the project are to be published in the Research Notes of the AAS and could change the way this stellar noise proxy is calculated by the exoplanet hunting community. Basic knowledge of python is required.
The stellar rotation period is an extremely important parameter that together with the depth of the convective zone is believed to generate a stellar dynamo and determine the activity of stars. Stellar activity decays during the lifetime of stars due to magnetic braking and angular momentum loss through stellar winds. The activity of a star at a given age will thus depend on the original rotational velocity and rotational history, which in turn will depend on the environmental condition at the formation and during the evolution of stars. There are several techniques to determine the rotational velocities of different types of stars, the most commonly used ones being based on i) rotational broadening of spectral lines, ii) periodic modulation of the stellar flux, and iii) periodic modulation of the spectral lines which are sensitive to stellar activity. While the last two techniques require substantial time-series photometric and/or spectroscopic observations (which are not always available or come at a cost) the first method is based only on a single spectroscopic observation. However, the determination of rotational velocities of stars with spectral line broadening technique requires very high-quality data (high spectral resolution and high signal-to-noise ratio) and is very challenging for slowly rotating stars. It is important to stress that this method allows us to determine the Vsin i, the stellar rotational velocity projected onto the line of sight. The aim of this project is to develop a tool to determine the rotational velocity of planet host stars observed with the ESPRESSO spectrograph. The measured rotational velocities will then be compared with the velocities determined by other techniques whenever available. This will allow us to i) validate the tool, and ii) determine the inclination (sin i) of the star’s rotation axis to the line of sight. In this project, the student will directly work with the highest quality spectral (ESPRESSO) and photometric (TESS) data of stars hosting planets. The knowledge the student will acquire during the project will be of high importance in the era of large spectroscopic and photometric planet search programs.
Wide binary stars formed from the same molecular cloud presumably have the same chemical composition. Binary twin stars (both components being physically very similar) with one component hosting a planet are the best laboratories to test the potential chemical signatures associated with planet formation. We will use the currently available sample of binaries with high-resolution spectra to make a uniform analysis of these systems. In particular, we will homogeneously determine the accurate chemical abundances of the binary components and will seek for possible correlations between abundance differences of the components and i) the properties of the planets such as mass, orbital distance and ii) the physical properties of the stars such as mass, temperature, and metallicity. In addition, we will study the impact of uncertainties of the stellar parameters on the chemical abundances of the stars. In this project, the student will directly work with the high quality spectral data of binary twin stars. The student will learn the techniques of high-precision spectroscopy and determine the chemical abundances of solar-like stars.
Planets from the Solar System like Venus, Jupiter and Saturn, have very dynamic and complex atmospheres that only recently have been studied in detail, thanks to several space missions and advances in the optical capabilities of telescopes. In particular, modern Cloud Tracking techniques allow for the compilation of the collected data in wind maps that help us understand the global wind circulation of a planet. In this internship, one will explore the atmosphere dynamics of different Solar System planets, applying Cloud Tracking methods to data obtained with terrestrial telescopes such as ESO’s Very Large Telescope (VLT), in Chile, or during space missions such as NASA’s Cassini-Huygens. But nowadays planetary science is no longer limited to the Solar System and more than 4100 exoplanets have been discovered so far around stars outside our Solar System, with very large ranges of masses, sizes and orbits. Even though huge steps have been taken in their characterization, from rocky terrestrial planets around cool stars to gaseous giants close to their parent star, the essential nature of exoplanets remains largely mysterious. Characterizing their atmospheres is the next step to elucidate the wide diversity of possible planetary environments. Current atmospheric characterization techniques address the study of exoplanets’ atmosphere mainly from three different viewpoints: 1) transmission spectroscopy, 2) phase variation and 3) occultation spectrophotometry. In this internship, we also propose to use Venus as a proxy to simulate how the transit of a cloudy “Venus analogue” would be observed if the planet was orbiting a star other than the Sun.
Acabaram de ser contactados pela Câmara Municipal de uma região cuja população tem um baixo interesse e participação em temas científicos. Vai ser construída uma grande infraestrutura de apoio à astronomia no concelho (p.e., um telescópio) e é essencial que a população local apoie o projeto. Foi-vos dado um orçamento para prepararem uma (ou mais) atividades que motivem aquele público em particular e vai ser necessária criatividade assente, contudo, na realidade. O objetivo final deste estágio será o planeamento de uma ação de comunicação/divulgação de ciência aplicada a um local específico e real, com um orçamento concreto, e que tem como propósito motivar e promover a participação da população local num empreendimento científico.