Recent Talks

List of all the talks in the archive, sorted by date.


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Thursday May 12, 2022
Dr. Eugene Vasiliev
IoA Cambridges

Abstract

I discuss the dynamical interactions between the Milky Way and its satellite galaxies, focusing on the closest and most massive satellites - the Large Magellanic Cloud (LMC) and the Sagittarius dwarf galaxy. The former just has had its first close encounter with the Milky Way very recently, and the latter has been orbiting our Galaxy for several Gyr and is tidally disrupting, leaving a prominent tidal stream spanning the entire sky. Thanks to the abundant and precise observational data from the Gaia satellite and various spectroscopic surveys, we now have a very detailed view of the Sagittarius stream and the remnant. It appears that to reproduce its observed properties, one needs to take into account the gravitational effect of the LMC itself and the effect that it produces on the motion of the Milky Way: an intricate dance of three galaxies. The LMC also affects the motion of other streams and satellite galaxies in the outskirts of the Milky Way, and I discuss an approach for compensating these perturbations in the context of dynamical modelling of the Milky Way mass distribution and the analysis of satellite orbits.


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Tuesday May 10, 2022
Dr. Alessia Ritacco
IAS/OAC

Abstract

The search for the primordial B-modes polarization in the cosmic microwave background (CMB) radiation,
carrying the signature of the primordial gravitational waves from the inflation epoch, motivated a significant
technological progress enabling the next generation of CMB instruments (e.g. CMB-S4, LiteBIRD)
to reach an unprecedented sensitivity. However, such a challenging detection demands a very high control
of the instrumental systematics and CMB foreground emissions.
Among those, the galactic dust polarized emission spectral dependence, not yet fully
characterized, could leave a high level of uncertainty in the cosmological polarization data
producing an ambiguous detection of the CMB B-modes.
Characterizing the dust spectral energy distribution (SED) spatial variations became one of
the most critical issues in the quest for primordial B-modes.
In the work that I will present we have used the release of the Planck satellite HFI data
obtained with the software Sroll2 (Delouis+2019, A&A 629, A38), in order to characterize
and compare the SEDs for polarization and total intensity.
The mean SEDs for dust polarization and total intensity from 353 to 100 GHz are confirmed
to be remarkably close. However, the data show evidence for spatial variations of the
polarization SED. These variations are correlated with variations of dust temperature
measured on total intensity data but the correlation is tight only in the Galactic plane.
At higher latitudes, by considering 90% of useful sky fraction and less, the amplitude of the dust
emission residuals in polarization suggests that an additional contribution, coming from
variations of the polarization angle, becomes dominant. Current models, which extrapolate
the SED spatial variations from total intensity to polarization, would be therefore grossly
simplifying and underestimating the foreground signal to CMB polarization.



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Tuesday May 10, 2022
Dr. Rosa Badia, Dr. Javier Conejero
BSC

Abstract

 PyCOMPSs is a task-based programming in Python that enables simple sequential codes to be executed in parallel in distributed computing platforms. It is based on the addition of python decorators in the functions of the code to indicate those that can be executed in parallel between them. The runtime takes care of the different parallelization and resource management actions, as well as of the ditribution of the data in the different nodes of the computing infrastructure. It is installed in multiple supercomputers of the RES, like MareNostrum 4 and now LaPalma. The talk will present an overview of PyCOMPSs, two demos with simple examples and a hands-on in LaPalma on how we can parallelize EMCEE workloads.

Slides and Examples: https://gitlab.com/makhlaghi/smack-talks-iac


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Friday May 6, 2022
Dr. Hugo García Vázquez
IAC

Abstract

Desde el 2019, en el Departamento de Electrónica del Área de Instrumentación del Instituto de Astrofísica de Canarias (IAC) se ha estado trabajando para tener la capacidad de diseñar y medir circuitos integrados con diferentes procesos tecnológicos. Gracias al proyecto EMIAC (Equipamiento Microelectrónica IAC) del Plan Nacional de Infraestructuras y posteriormente en menor medida al Plan de Recuperación, Transformación y Resiliencia, se está avanzando en la creación y puesta en marcha del Laboratorio de Circuitos Integrados (LABIC). El objetivo de esta presentación es mostrar el estado actual del laboratorio así como las líneas futuras.

 

Unirse a ZOOM:

https://rediris.zoom.us/j/84979227061

Emisión en Youtube:

https://youtu.be/Ec3Ktstx32o


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Thursday May 5, 2022
Dr. Francesca Calore
LAPTh

Abstract

 

In this presentation, I will review the history and literature debate about the anomalous gamma-ray emission detected towards the inner Galaxy by the Fermi-LAT telescope.
The so-called Fermi GeV excess has been first discovered in the early 2010s and later characterised by several, independent, research groups. 
While its main features are well established, the details of its spectral energy distribution and morphology remain debated.
Also the nature of this anomalous signal is unknown. Different interpretations have been put forward and scrutinised.
I will provide an overview of the most promising interpretations in terms of dark matter emission and faint astrophysical sources, and offer an outlook on how we can try to disentangle these two hypotheses with multi-wavelength and multi-messenger astrophysics.

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Tuesday May 3, 2022
Dr. Mireia Montes
IAC

Abstract

 

There is a huge amount of astrophysical events that remain barely studied due to the lack of large, multiwavelength and deep optical surveys. This is the Universe at the lowest density of stars, largely unseen by past large field surveys like the Sloan Digital Sky Survey (SDSS).  For instance, only a handful of galaxy clusters have been observed with enough depth to witness the intracluster light (ICL), made up of stars that drift freely between galaxies in the cluster. Thought to form by the stripping of satellite galaxies as they fall into the cluster, characterising the ICL is key to understanding the assembly mechanisms occurring inside galaxy clusters. Despite its importance, little is known about this light as it is very difficult to observe due to its low surface brightness. 
The availability of deep surveys have expanded our knowledge of the properties, and therefore the origin, of the ICL. However, larger samples are needed to understand the evolution of this component with time and the efficiency of the different evolutionary processes inside galaxy clusters. 
In this talk, I will present the latest advances in our understanding of the ICL. I will also talk about how we can use this light to trace the dark matter in clusters of galaxies and recent results that show the potential of the intracluster light to study these massive structures. 

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Friday April 29, 2022
Félix Gracia Temich
IAC

Abstract

Uno de los principales problemas que afecta no solo a la astrofísica sino a otros sectores de investigación e industria a nivel nacional, es la fabricación de elementos ópticos. De esta forma el CSOA se concibe para cubrir parte de esa demanda, no solo para fabricar elementos óptico tradicionales (esféricos y cónicos) y superficies u elementos ópticos no convencionales (asféricas, formas caprichosas, etc.). Para ello, debe contar con toda la infra estructura de última generación en cuanto a fabricación respecta, tales como sierras, generadoras, pulidoras, equipos de metrología y de recubrimientos ópticos para entregar un producto completamente funcional según se requiera. En esta breve charla hablaré de gran parte del equipo que se ha adquirido y ha sido entregado, lo que va situando al CSOA con la capacidad de ir ofreciendo ya algunos servicios.


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Friday April 22, 2022
Juan Ruiz Alzola
ULPGC/IAC

Abstract

Se hará una revisión de la tecnología de imágenes médicas, y de los métodos para su análisis y visualización. También se prestará atención a modelos de transferencia de tecnología a empresas en este campo. La computación de imágenes médicas es un campo multidisciplinar que involucra a médicos, ingenieros y científicos. Los campos que destacaremos son los métodos automáticos y semiautomáticos de procesado e interpretación de imágenes médicas, destacando en los últimos años la inteligencia artificial, que ha dado lugar a nuevos campos de investigación y aplicación, tales como la radiómica y la radiogenómica. También se discutirán las sinergias con la tecnología astrofísica y algunas posibilidades de I+D y trasnferencia desde el IAC.

Youtube: https://youtu.be/E_AVrcyqrO0

Unirse a la reunión Zoom

https://rediris.zoom.us/j/85927400095


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Thursday April 21, 2022
Dr. Robert Grand
IAC

Abstract

Recent years have seen impressive development in cosmological simulations for spiral disc galaxies like the Milky Way. I present a suite of high-resolution magneto-hydrodynamic simulations that include many physical processes relevant for galaxy formation, including star formation, stellar evolution and feedback, active galactic nuclei and magnetic fields. I will discuss how these processes affect the formation of galactic discs, and what these simulations can tell us about the formation of the Milky Way, such as the properties of the Galaxy's putative last significant merger and its effect on the formation of the thick disc and stellar halo. 


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Tuesday April 5, 2022
Prof. Brian Welsch
University de Wisconsin

Abstract

On the Sun, the presence of magnetic flux at the photosphere is closely linked to (1) steady heating of the overlying atmosphere and (2) transient brightenings, the largest of which are flares.   I will discuss statistical properties of both phenomena, with an emphasis on aspects of each that might apply to other astrophysical objects, such as other stars or stellar remnants, and perhaps AGNs.  Regarding heating, power-law scalings have been found to relate magnetic flux with steady coronal emission in both soft X-ray (SXR) and EUV ranges.  A key observation is that the details of magnetic structure (field strengths and their spatial gradients, including measured electric currents) appear not to affect heating rates. Similar SXR scalings have been reported for G,K, and M dwarfs and classical T-Tauri stars.  Departures from such scalings, whether on the Sun, other stars, or other objects, might reveal important aspects of the heating mechanisms that drive steady emission, and should be sought.   Regarding flaring, again a power-law scaling between magnetic flux and flare SXR emission has been found, but with a different exponent.  Differences in these scalings suggest that steady heating fundamentally differs from flare heating, disfavoring the “nanoflare” hypothesis (i.e., that steady coronal heating arises from many weak, unresolved flares that are essentially scaled-down versions of larger flares).  Analogous differences in the scalings of steady vs. flaring luminosities with magnetic flux on other objects could constrain processes driving each type of emission.  Another key property of flares is that they extract energy from the magnetic field, which in the solar case leads to measurable changes in field strengths after flares – photospheric field strengths tend to increase, coronal fields tend to decrease.  It is possible that analogous changes could be observed on other stars or objects (via, e.g., Zeeman or synchrotron  methods). 




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Recent Talks