Where are we ?
During the last two centuries, the experimentation and systematic observation of the surrounding Universe has lead us to tremendous developments in the fields of Quantum Mechanics, General Relativity and Particle Physics, allowing us to successfully explain the Universe around us. We now know that we live in a local Universe, most of which is composed by baryonic structures interacting between them through four fundamental interactions: gravitational, electromagnetic, strong nuclear and weak nuclear. However, Astrophysical and Cosmological observations tell us a very different story about the faraway Universe. Simply put, that it is an Universe formed by non-baryonic structures composed by particles that we do not know and physical interactions that we do not understand! The first theoretical inferences suggest that most of the new “unknown fundamental physics” is at the crossroads of particle physics, astrophysics and cosmology, although very likely obeying to laws of physics quite different to the ones we know.
This generation of physicists and astronomers have the huge challenge to discover the particle composition of these structures, and understand how these unknown particles, by the action of gravity, have created the Universe.
Moreover, it is a well established fact that the substantial progress in physics has been possible due to the exceptional technological progress in particle physics detectors, telescopes and astronomical satellites that allow us to discover the most fundamental particles of matter, as well as to observe the Universe in a multitude of wavelengths of the electromagnetic spectrum, or even start to probe the universe by means of new particles, like the neutrinos. It remains an uncomfortable truth that the future discoveries in experimental detectors are strongly limited by our technology, like the detection of gravitational waves by ground-based or space interferometers or new fundamental particles at large accelerator colliders! We need to find novel ways to study the Universe !
Our Goal ?
The main aim of our group is to use the “known Universe” to probe the “unknown Universe”: i.e., to use the Sun, the stars and most of the nearby Universe, as an “experimental detector” to look for the “new physics” that actively forms the structures in the faraway Universe.
Our Method ?
In the last 90 years, astronomers and physicists have built a robust model for the evolution of stars and the local Universe. During this period we have acquired large amounts of stellar and cosmological data, either from telescopes or satellite missions that in some cases span over several decades, an endeavour that will be strongly pursued by the next generation detectors, telescopes and satellites, observing the universe in all the electromagnetic spectrum, as well at the light of new particles, like neutrinos and cosmic rays. By taking advantage of this data across several research fields, we can test these new theoretical ideas in the Sun and stars to look for clues of the new physics that shapes the faraway Universe. This will also allow us to find the properties of “unknown particles” such as dark matter and to test “unknown interactions” like strong gravity.
What we do ?
Our main research projects are:
Sun and stars (in the Universe) - from particles to gravity: This research focuses on the study of the impact of dark matter particles in the Sun and the first generation of stars, using our stellar hybrid code (incorporating both astrophysics and particle physics) which follows the formation of stars in a rich dark matter environment, from the pre-main sequence phase until the red-giant branch. Particular emphasis is given to the study of the impact of dark matter candidates hinted by recent dark matter detectors. To constrain the dark matter properties, we use helioseismology data, solar neutrino data, astereoseismology data, photometric and spectroscopic data and Cosmology data. Moreover, we also investigate applications in classic astrophysics to improve our knowledge about the Sun and stars, including the mechanisms responsible for the solar and stellar magnetic activities.
Radio cosmology – Probing the dark ages: We use the next generation radio-telescopes to probe the large scale structure of the Universe and constrain the cosmological model. Particular emphasis was given to the study of the Epoch of Reionization, when the first non-linear structures were formed due to the gravitational collapse of the initial dark matter seeds. Both large-scale simulations and data analysis techniques were developed with radio telescopes in mind, such as the LOFAR and SKA. Following on this path, we have also explored the use of the radio signal, both using large galaxy survey and intensity mapping techniques, to constrain the nature of dark energy and even modifications to General Relativity.
Observational cosmology – Measuring the acceleration of the Universe: Our objective is to measure dark energy and its equation of state. Type Ia supernovas (SNIa) have been the undisputable candle to study the accelerated expansion of the Universe. However, systematic observational effects limit their use. We have acquired expertise in studying such observational effects. Our contribution has been pivotal to our membership participation in strategic international collaborations: CALIFA Galaxy Survey – to study the nearby SNe of all types, and the Supernova Cosmology Project and the Supernova Legacy Survey – to probe the nature of dark energy at high-redshift. Moreover, we are starting to explore the properties of high-redshift SNe that are gravitationally magnified by massive galaxy clusters.