Category: Máster

QCD axions as dark matter and their potential detection by gravitational microlensing

Jordi Miralda Escudé es ICREA Professor of Astrophysics Institut de Ciències del Cosmos

Abstract:The most distant single stars we have observed are in cases of extreme gravitational lensing magnification, when the source star crosses a lensing caustic of a cluster of galaxies that is affected by microlensing. This has enabled detections of stars at redshifts above unity with HST, and now with JWST to even fainter levels. If dark matter is smoothly distributed, microlensing should be caused only by intracluster stars, with rates and lightcurves of caustic crossings that have precise statistical predictions. Deviations from the shapes and other characteristics of these lightcurves are then a powerful probe to small-scale granularity in the dark matter, which is unavailable through other astronomical observations. In particular, if the QCD axion is present in the dark matter, minihalos predicted to have formed around the epoch of equalization can affect the lightcurves of stars that are supermagnified when crossing microlensing caustics.

Viernes 29 de septiembre, 12 horas, seminario de Física Nuclear . Online

Lecturer: Andrés del Pino Molina. Centro de Estudios de Física del Cosmos de Aragón (CEFCA). Astrophysics researcher with a strong computational and statistic background. Interested in resolved stellar populations, galaxies dynamics, and star formation

Abstract: The Milky Way system (MW) harbors dozens of known dwarf galaxies. Some of these systems have been studied for decades, offering us a glimpse on how diverse dwarfs can be in terms of their star formation histories, chemical composition, masses, etc. This has raised questions about the origin of these systems and on the possible mechanisms involved in their evolution. From the dynamical standpoint, some of the most obvious mechanisms proposed invoke the interaction of dwarfs with their massive host galaxy. However, based mostly on N-Body predictions and just line-of-sight velocity measurements, the discussion about the strength and efficiency of these mechanisms have remained largely speculative. Thanks to its unprecedented astrometric precision, the Gaia mission has changed that, giving us access to accurate 3D systemic motions of many known dwarfs satellites of the MW. For the first time, we can study the orbital histories of the MW satellites, which can shed light on the nature versus nurture discussion for these systems. In this talk, I will present a general overview on how the internal properties of  dwarfs are linked to their orbital history and on how the interaction with the MW has shaped them into the system we observe today.

Jueves 30 marzo, 12 horas

On line ( Zoom)

Artwork by KM3NeT with Sandbox Studio, Chicago

(more…)

Georg G. Raffelt, Max-Planck-Institut für Physik. His research is in the areas of theoretical astroparticle physics and cosmology. In particular, it revolves around weakly interacting particles (neutrinos, the hypothetical axion, or weakly interacting dark matter candidates), their role in astrophysics and cosmology.

(more…)

Miguel Á. Pérez Torres, research scientist at the Instituto de Astrofísica de Andalucía (IAA-CSIC, Granada, Spain) and collaborator of the DFTUZ

Abstract The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope. The SKA is expected to conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it many times faster than any current facility.
The SKA  will not be a single telescope, but a collection of telescopes spread over long distances in the Southern Hemisphere. In this talk, I will give an overview of the SKA project and its science goals, which range from the cradle of life in exoplanets up to shedding light on the Epoch of Reionization and the Dark Ages of the Universe.

(more…)

Cherenkov telescopes are instruments optimized for detection of very high energy (VHE, E > 100 GeV) gamma rays from astrophysics sources. They play a crucial role in testing possible consequences of Quantum Gravity (QG), such as violation or deformation of Lorentz symmetry. In both cases, the photon dispersion relation is modified, making the photon group velocity energy dependent, and possibly modifying kinematics and dynamics of electromagnetic interactions. These tiny effects are vastly below the sensitivity of present-day laboratories. However, if real, they could be measured using VHE gamma rays of astrophysical origin. Cosmological distances that they cross serve as a natural amplifier for the QG effects. While no deviations from the special relativistic predictions have been detected, strong constraints have been set on modified photon dispersion relations.
In this session we will explain the process of testing implications of modified photon dispersion relations on VHE gamma rays using Cherenkov telescopes. We will cover different stages from observations, Cherenkov telescopes’ data analysis, statistical methods employed, and finally setting constraints on the QG energy scale.

Jueves 12 mayo, 12 horas, seminario de Física Nuclear, on-line  (Google Meet)

Cartel

Diego Blas is a researcher at UAB (Universidad Autónoma de Barcelona) and IFAE (Instituto de Física de Altas Energías). His research interests are in theoretical physics, gravitation and cosmology.

Abstract: In this talk, current and future efforts to detect gravitational waves from Earth and space observatories will be reviewed. Diego will also emphasise the physical consequences of these searchers, in particular regarding fundamental physics (primordial cosmology, dark matter, modified gravity…)

Viernes 6 mayo, 12 horas, seminario de Física Nuclear. On-line (Google-meet)

Charla de Diego Blas (cartel)