Início » Tecnologia & Inovação » Webinars Técnico » 2022
15/12 - 11:00 am
Cullan Howlett
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Cullan Howlett
Title
Cosmology and cosmography with galaxy peculiar velocity surveys (University of Queensland)
Abstract
Direct measurements of galaxy peculiar velocities, i.e., their motions with respect to us beyond that expected from just the expansion of the Universe, are undergoing a resurgence. Five years ago, individual surveys were limited to a few thousand galaxies and to within the z~0.05 Universe. With the newest state-of-the-art, the number of galaxies, and the cosmological volume they cover, will increase by more than an order of magnitude. In this talk I will present the motivation and mechanisms for carrying out these measurements, focusing on both how they can be used to provide more precise tests of General Relativity on large scales than are possible with just galaxy redshifts, and how they can be used to create detailed cosmographic maps of hidden structures in the nearby Universe. As an example, I will discuss the construction and new cosmological results from my recently released Sloan Digital Sky Survey peculiar velocity catalogue. I will finish the talk by highlighting the exciting upcoming results we expect from the next generation of peculiar velocity surveys being carried out with the Dark Energy Spectroscopic Instrument (DESI) and 4-Metre Multi-Object Spectroscopic Telescope (4MOST).
Slides not available
08/12 - 11:00 am
Claudia Maraston
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Claudia Maraston
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Stellar population models and clues to galaxy evolution (University of Portsmouth)
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Evolutionary population synthesis models describing the energetic emission and stellar mass distribution of galaxies and star clusters are the essential interpretative tool in astrophysics and cosmology. They are used to infer key properties of stellar systems (age, chemical composition, stellar mass, dark matter fraction) from data, to predict the spectral energy distribution of simulated galaxies, to trace galaxy ages as a function of cosmic time for constraining cosmology, to predict the number, mass and location of stellar remnants rooting gravitational waves. Given their widespread use, the accuracy of population synthesis models directly affect our understanding of galaxy formation and evolution in a cosmological context. I shall review progress and difficulties and discuss key applications of these models over cosmic time.
Slides not available
01/12 - 11:00 am
Ana Chies Santos
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Ana Chies Santos
Title
Globular cluster systems as probes of the build-up of galaxies and their environments (Federal University of Rio Grande do Sul)
Abstract
Globular clusters (GCs) are found in galaxies spanning a large range of masses, from giants to dwarfs, and because of their high surface brightnesses, they can be readily identified up to distances z~0.2 with the Hubble Space Telescope. The properties of GC systems are intrinsically connected to the assembly histories of their host galaxies, and they can be used as tracers of the total mass of their parent halos. Moreover, GCs are not only found in the bodies of their host galaxies but also free-floating in galaxy clusters, not necessarily bound to a host galaxy. In this talk, I will review the main properties of globular cluster systems across a range of masses and environments and present recent works from our group on the topic. I will show our current efforts to map GC systems through multi-band imaging around the surprisingly neglected nearby spiral galaxies, relic galaxies, and low surface brightness galaxies. I will finish by showing prospects for the field in the coming years with the new generation of ground-based surveys and space facilities.
Slides not available
17/11 - 11:00 am
Sebastian Bocquet
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Sebastian Bocquet
Title
Cluster Cosmology with the South Pole Telescope (Ludwig-Maximilians-University of Munich)
Abstract
Cluster Cosmology with the South Pole Telescope
Slides not available
10/11 - 01:00 pm
Pablo Santos-Sanz
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Pablo Santos-Sanz
Title
Unveiling the trans-Neptunian belt through thermal data and stellar occultations (Instituto de Astrofísica de Andalucía)
Abstract
Physical knowledge of trans-Neptunian objects (TNOs) and Centaurs has improved in recent years thanks to more sensitive observations of their thermal emission with the Spitzer and Herschel space telescopes. Thermal emission from TNOs/Centaurs has also been measured with ALMA, WISE, and other ground- and space-based radio facilities. These data allow, by means of thermal or thermophysical models, to obtain the diameters and albedos of these bodies with uncertainties of ~10% in diameters and ~20% in albedos. Thermal properties such as thermal inertia or surface roughness can also be obtained. In total, we have thermal measurements for ~180 TNOs/Centaurs, for which we have obtained equivalent diameters, albedos, and thermal properties. On the other hand, stellar occultations produced by TNOs and Centaurs are a very direct and elegant way to obtain sizes (with a few kilometers of uncertainty), shapes, and albedos of these bodies from the timing of a star disappearing and reappearing behind the object’s limb. In the last decade, it has been possible to predict and observe stellar occultations by TNOs/Centaurs thanks to the better knowledge of their orbits and the improvement of stellar positions from the available stellar catalogs. To date, stellar occultations produced by ~50 TNOs/Centaurs have been observed, obtaining an accurate determination of their sizes and albedos. Thermal emission is available for most of these ~50 objects. There is a clear synergy between thermal measurements and stellar occultations and it is possible to combine the results of both techniques to obtain a better physical and thermal characterization of these bodies.
Slides not available
20/10 - 11:00 am
Renu Malhotra
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Renu Malhotra
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Pluto near the edge of strong chaos (University of Arizona)
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Slides not available
13/10 - 11:00 am
Tessa Baker
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Tessa Baker
Title
Beyond standard sirens: gravitational wave cosmology without electromagnetic counterparts. (Queen Mary University of London)
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Slides not available
06/10 - 11:00 am
Sebastian Grandis
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Sebastian Grandis
Title
Towards robust cluster cosmological inference (University of Innsbruck)
Abstract
Number counts of galaxy clusters are a well established cosmological probe, which infers the cosmological model by measuring the abundance of clusters as a function of their mass and cosmic age. We review first the key ingredients for cluster cosmological inference, identifying two main regions of systematic uncertainty: cluster mass measurements and cluster selection modelling. Based on recent work for the South Pole Telescope and the Dark Energy survey cluster cosmological analyses, we present how to tackle these issues via a combination of Bayesian population modelling, cosmological volume hydrodynamical simulations and multi-wavelength observations. Finally, we outline how these new methods will lead to robust cluster cosmological inference in the age of the next generations surveys like eROSITA, Rubin, Euclid, and CMB-Stage IV.
Slides not available
29/09 - 10:00 am
Elisa Maria Alessi
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Elisa Maria Alessi
Title
Natural perturbations as allies to design deorbiting solutions to mitigate the space debris problem. (Istituto di Matematica Applicata e Tecnologie Informatiche)
Abstract
The aim of this presentation is to introduce the problem of space debris and the actions that the worldwide community is taking to mitigate it. I will focus in particular on the role of end-of-life disposal strategies and how natural perturbations and advanced mathematical tools can help to design orbital solutions to preserve the orbital regions around the Earth.
15/09 - 11:00 am
Vincent Desjacques
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Vincent Desjacques
Title
Dynamical friction on circular orbits (Technion)
Abstract
The gravitational field of a massive object moving in a discrete or continuous medium induces a density wake in that medium. Dynamical friction is the gravitational force exerted on the perturber as a result of the induced density fluctuation. The pioneering study of Chandrasekhar (1943) considered a perturber linearly moving in a collisionless medium. In this talk, I will present an analytic approach to the dynamical friction acting on circularly moving point masses in a gaseous medium. I will show how it can be extended to axion dark matter backgrounds. Some astrophysical implications will also be discussed.
Slides not available
08/09 - 11:00 am
Joel Johansson
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Joel Johansson
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Type Ia supernovae in the Infrared (Stockholm University)
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Slides not available
01/09 - 11:00 am
Pierluca Carenza
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Pierluca Carenza
Title
A glimpse of axion phenomenology in astrophysics (Stockholm University)
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The old and successful idea of using astrophysical systems as laboratories for fundamental physics is becoming extremely popular nowadays. Axions are a remarkable example of Feebly Interacting Particles playing an important role in astrophysical phenomena. It is well-known that stars are powerful axion factories, giving strong constraints on their properties. Aspects of the axion phenomenology in horizontal-branch stars and supernovae are reviewed.
26/05 - 02:00 pm
Sierra Villarreal
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Sierra Villarreal
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Extreme Scale Image Simulation Workflows for LSST DESC (Argonne National Laboratory)