Imatge de diagramació Imatge de diagramació Imatge de diagramació Imatge de diagramació
Logo Universitat de Barcelona

Facultat de Física

Imatge de diagramaci�
Inici Facultat Inici UB   
Imatge de diagramació
Agenda/Conferències i seminaris Imatge de diagramació
Imatge de diagramació Imatge de diagramació
Imatge de diagramació Imatge de diagramació Imatge de diagramació
Imatge de diagramació

 
 
   

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, Dimarts 15 de Octubre de 2019, a les 12:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: The (endless) quest for obscured AGN
Conferenciant: Cristian Vignali (Università di Bologna)
Abstract:

In the last twenty years, X-ray surveys have revealed that a significant fraction of accretion through cosmic time is obscured. In this talk I will highlight some recent results obtained by combining the strength of deep X-ray observations (as those in the Chandra Deep Field North and South, and COSMOS) with optical/mid-IR information. In particular, mid-IR data, have been invaluable in offering complementary methods to select obscured AGN also in cases where the nuclear X-ray emission below 10 keV is largely obscured. The net effect of this multi-band observing strategy is to provide
a more complete census of the obscured AGN population, hence clues to the AGN-galaxy co-evolution scenario, up to very high redshift (z~6). Prospects for forthcoming X-ray and mid-IR facilities will be also discussed.

Lloc: Seminari DAM (724)
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1402

Facultat de Física, Dimarts 15 de Octubre de 2019, a les 12:00h

Seminari del Dep. de Física de la Matèria Condensada

Títol: Magnetocaloric Effect: From Energy Efficient Refrigeration to Fundamental Studies of Phase Transitions
Conferenciant: Victorino Franco (Universidad de Sevilla)
Abstract:

The magnetocaloric effect, that is, the reversible temperature change experienced by a magnetic material upon the application or removal of a magnetic field, has become a topic of increasing research interest due to its potential applications in refrigeration at ambient temperature that is energy efficient and environmentally friendly. From a technological point of view, the improvement of magnetic refrigeration systems can have a notable impact on society: a large fraction of the electricity consumed in residential and commercial markets is used for temperature and climate control. From the point of view of magnetic materials, research on this topic mainly focuses on the discovery of new materials with lower cost and enhanced performance. In addition, the characterization of the magnetocaloric effect can be used for more fundamental studies of the characteristics of phase transitions. I will cover an overview of the phenomenon and a classification of the most relevant families of alloys and compounds. I will analyze possible limitations for the optimal performance of the materials in magnetic refrigerators, including hysteretic response and cyclability. Regarding phase transitions, I will present a new method to quantitatively determine the order of thermomagnetic phase transitions using the field dependence of the magnetic entropy change. For second-order phase transition materials, I will show that critical exponents can be determined using the magnetocaloric effect even in cases where the usual methods are not applicable . In the case of first-order phase transitions, more details about their hysteretic response can be obtained using T-FORC .

Lloc: Aula seminari 3.20
Contacte: amilcar.labarta@ub.edu
Web: http://ieeemagnetics.org/index.php?option=com_content&view=article&id=292:victorino-franco&catid=84:2019-distinguished-lecturers&Itemid=189

Facultat de Física, Dimecres 16 de Octubre de 2019, a les 11:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: Weak lensing with uncertain redshifts
Conferenciant: Alan F. Heavens (Imperial College London)
Abstract:

The cosmological conclusions of weak lensing surveys are very sensitive to the assumed redshift distributions of sources placed in different tomographic bins. In reality, these distributions are not known quantities, so from a Bayesian perspective they should be treated as random objects, constrained by data. For photometric redshifts, the data are fluxes in a number of bands. In this talk, we look at the influence of this redshift uncertainty from a principled Bayesian perspective, and show how, in the case of the KiDS-Viking 450 cosmic shear survey, this approach changes the tension that exists between the results and Planck-derived parameters, indicating either a stronger case for new physics, or a weakening of the tension.

Lloc: Seminari DAM (724)
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1404

Facultat de Física, Divendres 18 de Octubre de 2019, a les 12:00h

Confèrencia de l'Institut de Ciències del Cosmos

Títol: ICCUB Colloquia | Applied string theory: Understanding strange metals in the lab with virtual black holes
Conferenciant: Koenraad Schalm
Abstract:

The Anti-de-Sitter/Conformal Field Theory correspondence, also known as AdS/CFT, has given us an unprecedented new holographic window in strongly coupled physics.
In particular the existence of charged black holes in AdS predicts the existence of novel quantum critical fixed points distinct from the conventional theory of critical phenomena. I will review how the distinct features of these novel quantum critical points show a remarkable resemblance with the profoundly mysterious behavior of exotic strange metal states of quantum matter, e.g. in high Tc superconductors. Recent experiments of the past two years strongly indicate that this resemblance is more than superficial. This has put us at the cusp of a new era in theoretical physics: we will present the case that current experiments can and will test a holographic gravity model as the theory of the strange metal state.

Lloc: Aula Magna
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1367

Facultat de Física, Dilluns 21 de Octubre de 2019, a les 11:40h

Seminari de l'Institut de Ciències del Cosmos

Títol: QGP tomography through dynamical energy loss formalism
Conferenciant: Dr. Magdalena Djordjevic (Institute of Physics Belgrade)
Abstract:

Quark Gluon Plasma (QGP), is a new form of matter, consisting of interacting quarks, antiquarks and gluons, which are no longer confined. It is believed that QGP existed few µs after the Big-Bang, marking the beginning of the universe. Today, QGP is explored through Little Bangs in ultra-relativistic heavy ion collisions at the LHC (CERN) and RHIC (BNL, USA). By now it is widely accepted that QGP is discovered in these experiments, with the current challenge to understand its properties.

Lloc: Aula 507 (Pere Pascual)
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1395

Facultat de Física, Dilluns 21 de Octubre de 2019, a les 12:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: Inferring the dynamical growth of structures at high-redshift
Conferenciant: Natàlia Porqueres (Imperial College of London)
Abstract:

While the standard model of cosmology fits most cosmological observations to extraordinary accuracy, some tensions between the model and observations seem to persist despite the increasing quality of data.
Although these tensions might be related to systematic effects, they can also be the first signs of new physics. New insights into these open questions can come from the analysis of the non-linear matter distribution. For this reason, the next generation of surveys will map the galaxy distribution out to z~3. However, future surveys will be limited by survey systematic effects. To address this problem, I will present a new data model that is insensitive to survey systematics and provides unbiased results from data subject to unknown contaminations. Complementary to galaxies, the Lyman-alpha forest traces the under-dense regions of the Universe with very high resolution. By tracing scales down to a few Mpc, the Lyman-alpha forest is sensitive to neutrino masses and dark matter models. In this talk, I will present a Bayesian framework to infer the matter distribution and its dynamics at z>2 from the Lyman-alpha forest.
This method provides the dark matter density and velocity fields as well as unbiased cluster and void profiles.

Lloc: Seminari DAM (724)
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1407