# Recent Talks

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

Friday May 14, 2021
Drs. Iciar Montilla
IAC

## Abstract

The AO system of the 10-m class Gran Telescopio Canarias is in its final test phase in the lab at the Instituto de Astrofísica de Canarias. It has to successfully pass all the system tests to carry out the factory acceptance and be shipped to Roque de Los Muchachos Observatory (ORM) in 2021. Designed to be a facility, robustness and operability are two of its key characteristics. A series of calibrations are required and methodically run to achieve its ultimate performance.
I will detail in this talk the full characterization of the system, allowing to verify the compliance with the specifications and paving the way towards shipping the system to ORM.

Unirse a la reunión Zoom
https://rediris.zoom.us/j/88097037502?pwd=eWY0eWx4QzRFN2U4Q0wyZVk2ODc1UT09

ID de reunión: 880 9703 7502
Código de acceso: 392830

Thursday May 13, 2021
Prof. Diego Blas
Imperial College

## Abstract

Bosonic ultra-light dark matter (ULDM) in the mass range m ~ $10^{-22} - 10^{-21} \rm eV$ has been invoked as a motivated candidate with new input for the small-scale `puzzles' of cold dark matter. Numerical simulations show that these models form cored density distributions at the center of galaxies ('solitons'). These works also found an empirical scaling relation between the mass of the large-scale host halo and the mass of the central soliton. We show that this relation predicts that the peak circular velocity of the outskirts of the galaxy should approximately repeat itself in the central region. Contrasting this prediction to the measured rotation curves of well-resolved near-by galaxies, we show that ULDM in the mass range m ~ $10^{-22} - 10^{-21} \rm eV$ is in tension with the data.

Tuesday May 11, 2021
Prof. Rodrigo Alonso
Durham University

## Abstract

Cosmological and astrophysical experimental data demark a large share of the limits of our knowledge in fundamental physics. I'll review two pieces of evidence of our ignorance: the nature of dark matter and the generation of baryon asymmetry in the universe, together with some of the proposed solutions to each. Finally, a novel connection between the two open problems will be presented.

Friday May 7, 2021
Jesús Patrón Recio
IAC

## Abstract

El propósito de esta charla es comentar una serie de aspectos y detalles del día a día en la gestión de proyectos que quizás no sean tan del dominio público como el clásico control del alcance, coste y tiempos en el ámbito de un proyecto. Aparte de las tareas y herramientas específicas para el seguimiento de las actividades dentro de un proyecto, que implican el manejo de múltiples tablas y documentación, con paquetes de trabajo, definición de tareas, distribución de un árbol de producto, listado de requerimientos, tablas de presupuestos, listado de entregables, etc., el día a día de la gestión implica una serie de trámites, procesos y acciones de todo tipo, grandes y pequeñas, que, poco a poco, van sumando su granito de arena a la montaña sobre la que se asienta el progreso diario de un proyecto.

Thursday May 6, 2021
Prof. John Tonry
University of Hawaii

## Abstract

The "Asteroid Terrestrial-impact Last Alert System" (ATLAS) is funded by NASA to find dangerous asteroids before they strike the Earth. It has operated from two Hawaii sites since 2015 and will very soon have South Africa and Chile sites to cover the entire visible sky every night four times to a limiting magnitude of m~19.5 per exposure. The process of finding asteroids leads to auxiliary data products along the way including accurate photometry of all stars in the sky and detection of flares and transients.  I will describe ATLAS, how we approach our NASA mission to find NEOs, how ATLAS fits in with other ongoing or planned surveys, some of the data products that are available now, and the many new scientific opportunities that are emerging and waiting to be exploited.  Time will be reserved at the end of the talk for some real time demonstrations: audience participation is encouraged.  References include 2018PASP..130f4505T, our public web page at fallingstar.com and fallingstar.com/weather/ to see our current fisheye and webcam views at all four sites.

Meeting ID: 822 4128 8569
Passcode: 776606

Tuesday May 4, 2021
Prof. Lyndsay Fletcher
University of Glasgow / University of Oslo

## Abstract

A solar flare involves the conversion of magnetic energy stored in the coronal magnetic field into the kinetic energy of thermal and non-thermal particles, mass motion, and radiation. How this happens remains a central question in solar physics. A particular long-standing puzzle is how such a high fraction of the stored magnetic energy - up to a half - arrives in the kinetic energy of accelerated non-thermal particles. In this talk I will present an observational overview of solar flares with an emphasis on accelerated particles, discuss some ideas and constraints on particle acceleration, and present some new observations of the possible role of plasma turbulence in the acceleration process.

Friday April 30, 2021
Francisco Hernández Hernández
IAC

## Abstract

Planes originales de software de control, en que ha quedado y que se esta realizando finalmente

Thursday April 29, 2021
Prof. Steen Hansen
COpenhagenUNi / DARK cosmology center

## Abstract

The expansion of the Universe is in an accelerated phase. This
acceleration was first estabilished by observations of SuperNovae, and
has since been confirmed through a range of independent observations.

The physical cause of this acceleration is coined Dark Energy, and
most observations indicate that Einsteins cosmological constant
provides a very good fit. In that case, approximately 70% of the
energy of the Universe presently consists of this cosmological
constant.

I will in this talk address the possibility that there may exist other
possible causes of the observed acceleration. In particular will I
discuss a concrete model, inspired by the well-known Lorentz force in
electromagnetism, where Dark Matter causes the acceleration.  With a
fairly simple numerical simulation we find that the model appears
consistent with all observations.

In such a model, where Dark Matter properties causes the acceleration
of the Universe, there is no need for a cosmological constant.

Tuesday April 27, 2021
Dr. Lorenzo Posti
Observatorie Astronomique de Strasbourg

## Abstract

It is widely understood that galaxies use, throughout the Hubble time, only a small fraction of the baryons associated to their dark matter halos to form stars. Such low baryon-to-stars conversion efficiencies are expected in galaxy formation scenarios where stellar & AGN feedback play a key role in regulating star formation in galaxies, respectively at the low- and high-mass end.
In this talk I will show how we can constrain this scenario using galaxy dynamics. Both robust determinations of disc dynamical scaling relations (e.g. Tully-Fisher, mass-size) and accurate measurements of dark matter halo masses from HI rotation curves of spirals and from the kinematics of globular clusters around ellipticals, provide compelling evidence that the population of massive spirals has systematically larger baryon-to-stars conversion efficiencies than ellipticals. In fact, we see that the baryon-to-stars conversion efficiency monotonically increases with mass for late-type galaxies, while it shows a clear turn over at about L* only for early-type galaxies. Thus, while massive early types are compatible with standard stellar-to-halo mass relations based on abundance matching, massive late types are systematically discrepant from it.
I will discuss the possible repercussions that these results have, highlighting in particular what they imply in terms of AGN feedback and merging in galaxies of different types. Finally I will show that current state-of-the-art cosmological hydrodynamical simulations (EAGLE, TNG) still struggle to reproduce what we observe for the most massive discs.

Friday April 23, 2021
Dr. Diego Tuccillo
Instituto de Astrofísica de Canarias

## Abstract

Pandas is an open source Python package that is widely used for data analysis. It is a powerful ally for data munging/wrangling and databases manipulation/visualisation, and a must-have tool for Data Scientists. In this seminar we will have a general overview on its functionality and we will run over some of the reasons of its large success in the Data Science community.

## Upcoming talks

More upcoming talks