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El límit per poder anunciar en paper seminaris i conferències en els ascensors és el divendres a les 12 hores de la setmana anterior. Amb posterioritat a aquesta data el seminari o conferència quedarà només recollit al web de la Facultat. Aleshores la publicitació en paper serà responsabilitat dels organitzadors.



Facultat de Física, de Dilluns 20 de Novembre de 2017 a Dimecres 22 de Novembre de 2017, a les h

Curs de l'Institut de Ciències del Cosmos

Títol: An introduction to Bayesian Statistics through Astronomical Application
Conferenciant: Cecilia Mateu (CIDA (Venezuela))
Abstract:

Schedule: 20, 21 and 22 of November from 17:40 to 19:00

Programme:

Lecture 1:
The concept of probability in Bayesian Statistics. The Sum and Product Rules. Bayes’s Theorem.
Example: Least Squares Minimization - Chi2.
The Coin Example (the effect of sample size and varying priors).

Lecture 2:
Nuisance parameters and Marginalization.
Example: An Astrophysical application of the Coin Example Confidence Intervals. Coordinate Transformations.
Examples: Derivation of the ‘Sum in Quadrature’ rule,computation of confidence intervals in N-dimensions.

Lecture 3:
Probability distributions: example applications. Fitting a density modelto data (Poisson).
Inference with many parameters: the “astrophysical coin” example using Markov Chain Monte Carlo.

The course is open to all pre- and postdoc students

Lloc: V12M (Facultat de Física)
Contacte: tantoja@fqa.ub.edu
Web: http://icc.ub.edu/activity/1072

Facultat de Física, Dimarts 21 de Novembre de 2017, a les 11:45h

Seminari del Dep. de Física Quàntica i Astrofísica

Títol: Spinning superfluid helium-4 nanodroplets
Conferenciant: Manuel Barranco (FQA)
Abstract:

Motivated by recent experiments, spinning superfluid helium-4 nanodroplets have been addressed. It will be shown the crucial role played by the presence of quantized vortex arrays to reconcile theory and experiment. The capture of impurities by vortices in helium-4 droplets will be also discussed.

Lloc: Aula Pere Pascual (507)
Contacte: bruno@fqa.ub.edu
Web: http://www.ecm.ub.es/~bruno/fansem/semweb.html

Facultat de Física, Dimarts 21 de Novembre de 2017, a les 11:45h

Seminari del Dep. de Física Quàntica i Astrofísica

Títol: Scalar Instabilities in AdS and dS
Conferenciant: Aron Jansen
Abstract:

I will show a very simple QCD inspired holographic model that has surprisingly rich dynamical behavior.
It has a dynamical instability that violates the correlated stability conjecture, and that can result in a runaway solution with an exponentially growing horizon area.
This furthermore seems rather generic behavior for Einstein-scalar theories with a scalar potential that is “steep enough”.
If time permits I will also discuss a more recent project concerning quasinormal modes of a Reissner-Nordstrom de Sitter black hole, and their relation to the strong cosmic censorship conjecture.

Lloc: Aula 507 (Pere Pascual)
Contacte: vicente.atal@icc.ub.edu
Web:

Facultat de Física, Dijous 23 de Novembre de 2017, a les 12:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: New candidate RR Lyrae star streams in the inner Galaxy
Conferenciant: Cecilia Mateu (CIDA (Venezuela)
Abstract:

In this talk we will present our findings of fourteen new candidate RR Lyrae stellar streams in the inner galaxy, found with the great circle cell method GC3 applied to the Catalina Surveys of RR Lyrae stars (Mateu, Read & Kawata, 2017). This is a first application of a method we have extended and fully characterised in previous works (Mateu et al. 2011, 2017a), with the goal of conducting a full stream census in the Milky Way using Gaia, as soon as DR2 is released next year. We discuss our findings in connection to globular cluster stream models. We will also present the new GALSTREAMS Python library, in which we provide the footprints of known streams and overdensities in the Milky Way to facilitate comparison with new found substructure.

Lloc: Room 507 (Pere Pascual), 5th floor
Contacte: cesca@fqa.ub.edu
Web: http://icc.ub.edu/activity/1073

Facultat de Física, Dijous 23 de Novembre de 2017, a les 14:00h

Seminari del Dep. de Física Quàntica i Astrofísica

Títol: A smooth exit from eternal inflation
Conferenciant: Thomas Hertog
Abstract:

I discuss recent work in collaboration with Stephen Hawking in which we argue that the holographic form of the no-boundary wave function predicts that eternally inflating universes are smoother on very large scales than hitherto thought.
As a warmup I describe and comment on the recent controversy surrounding the Hartle-Hawking no-boundary proposal for the quantum state of the universe.

Lloc: Aula 507 (Pere Pascual)
Contacte: vicente.atal@icc.ub.edu
Web:

Facultat de Física, Divendres 24 de Novembre de 2017, a les 12:00h

Seminari del Dep. de Física de la Matèria Condensada

Títol: 2d active dumbbell model: Diffusive behavior and aggregation phenomena
Conferenciant: Pascuale Digregorio (Univ. Bari)
Abstract:

Active matter is constituted by self-propelled units that extract
energy from internal sources or its surroundings, and are also in
contact with an environment which allows for both dissipation and
thermal fluctuations. The locally gained energy is partially converted into work and partially dissipated into the bath. Due to this energy consumption detailed balance is broken in active matter, pushing these systems out of thermodynamic equilibrium.
Our active matter model is a 2d Active Brownian Particle model in
which the constituents are dumbbells, simplified model for diatomic molecules, interacting with each other by means of a short-range purely repulsive WCA potential.

We have studied the mechanism for melting of our system in the passive limit and we found a non-trivial KTHN-like scenario with a first-order phase transition, marked by a region of co-existence between disordered liquid/gas regions and regions with hexatic order.

Moreover, we have extended the analysis to the active case, and we have found co-existence over a finite interval of packing fractions for each value of activity. We didn’t find no discontinuous behavior upon increasing activity from the passive limit.

Lloc: 3.20
Contacte: demianparatodos@gmail.com
Web:

Facultat de Física, Divendres 24 de Novembre de 2017, a les 12:00h

Seminari del Dep. de Física Quàntica i Astrofísica

Títol: Gravitational Waves from Axion Monodromy Inflation
Conferenciant: Fabrizio Rompineve
Abstract:

Large field inflation is arguably the simplest and most natural
variant of slow-roll inflation. Axion monodromy may be the most promising framework for realising this scenario. As one of its defining features, the long-range polynomial potential possesses short-range, instantonic modulations. These can give rise to a series of local minima in the post-inflationary region of the potential. In this talk, we show that for certain parameter choices the inflaton populates more than one of these vacua inside a single Hubble patch. This corresponds to a dynamical phase decomposition, analogously to what happens in the course of thermal first-order phase transitions. In the subsequent process of bubble wall collisions, the lowest-lying axionic minimum eventually takes over all space.
This violent process sources gravitational waves, very much like in the case of a first-order phase transition. We discuss the energy density and peak frequency of the signal, which can lie anywhere in the mHz- GHz range, possibly within reach of next-generation interferometers.

Lloc: Aula 507 (Pere Pascual)
Contacte: vicente.atal@icc.ub.edu
Web:

Facultat de Física, Dilluns 27 de Novembre de 2017, a les 9-14hh

Workshop de la Facultat de Física

Títol: IN2UB - CBNI Symposium
Conferenciant: Kenneth Dawson (CBNI), Yan Yan (CBNI), Mª Antònia Busquets (IN2UB), Miguel Rubí (IN2UB)
Abstract:

A Symposium between researchers from IN2UB and CBNI about the application of nanotechnology into biological systems from both a practical and a theoretical point of view.

Lloc: Eduard Fontseré
Contacte: isaborit@ub.edu
Web: http://www.ub.edu/in2ub/files/PROGRAM_IN2UB_CBNI.pdf

Facultat de Física, Dimecres 27 de Desembre de 2017, a les 19:00h

Confèrencia de l'Institut de Ciències del Cosmos

Títol: Explosions de Supernova: La persistència de la memòria
Conferenciant: Carles Badenes
Abstract:

En aquesta xerrada es donarà una perspectiva general dels coneixements actuals sobre explosions de supernova: què són, quin paper juguen en l’evolució estelar, i quina relació tenen amb l’origen dels elements químics al nostre Univers.
Existeix un tipus concret d’explosions de supernova, les anomenades supernoves de Tipus Ia o termonuclears, que segueix sent un misteri pels astrofísics, perquè encara no es coneix amb detall el tipus d’estrelles que les provoquen. Es parlarà de quines hipòtesi es consideren més plausibles i de com les podem contrastar amb dades observacionals.

En el marc de la celebració del 25 aniversari de la Sociedad Española de Astronomía.

Lloc: Aula Magna Edifici Històric Universitat de Barcelona
Contacte: divulgacio@icc.ub.edu
Web: http://icc.ub.edu/activity/1068