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ARCCOS. Action de Recherche Concertée en COSmologie
Joint FUNDP-UCLouvain Research Action in Cosmology
Principal Investigators:
A. Füzfa1, C. Ringeval2
1Namur Center for Complex Systems (naXys), FUNDP
2Center for Cosmology, Particle Physics and Phenomenology (CP3), UCLouvain
The aim of this ARC project is to constitute a new research pole in cosmology within the Louvain Academy, by reinforcing the existing workforce, by making the most of the experience in both teams and by contributing to the visibility of the Academy at the national and international levels. This inter-university collaboration constitutes a launching pad to boost the settlement of a true pole in Cosmology inside the Louvain Academy by creating a core team and network of active young researchers working on both sites, to exchange the present experience and achieve high-quality scientific publications in common.
The topic of this project is the interplay between dark energy and primordial inflation. A bunch of recent cosmological data on cosmological expansion, temperature fluctuations in the cosmic microwave background (CMB) and properties of large-scale structures has greatly improved our current understanding of the universe. This notably helped establishing the so-called concordance model, the “Lambda Cold Dark Matter” (ΛCDM) model, an interpretation of various puzzling observations that lies in agreement with most of the current observations: those associated with CMB but also distance-redshift relations probed by the type Ia supernovae as well as the large scale distribution of galaxies.
The concordance model ΛCDM is a hot Big-Bang scenario with late accelerated cosmic expansion, as originally proposed by Georges Lemaître, which involves two new forms of energy in addition to ordinary matter and radiation. The first is the so-called “Cold Dark Matter”, a pressureless cosmological fluid weighting just as ordinary matter but not coupled to electromagnetism: it does not interact with light. The second, dubbed ”Dark Energy” is usually modeled through a non-vanishing cosmological constant Λ in the Einstein’s equations of gravitation. Those exotic ingredients together constitute most of the present universe (∼ 95%) but are indeed essentially made of constituents still undetected in our laboratories and not predicted or understood through the Standard Model of Particle Physics. Therefore, many theoretical works are devoted to the understanding of the nature and interplay of these two constituents.
Another important result stemming from these observations concerns the flatness of space, a situation that is highly coincidental in cosmology. This curiosity was actually a prediction made in the 1980’s by cosmic (or primordial) inflation. Cosmic inflation is a phase of accelerated expansion which is supposed to have occurred in the very early ages of the universe, well before the emission of the CMB. This primordial accelerated era cannot be caused by a cosmological constant because otherwise it would have never end. Another mechanism has to be proposed, whose details are still unknown. Nonetheless, primordial inflation is now considered as the standard approach to the early universe. In addition to have predicted the flatness of space, primordial inflation provides a solution to the so-called monopoles problem, it predicts the statistics and complete power spectrum of the CMB fluctuations; all of these properties being in agreement with the measurements.
The similitudes between primordial inflation and the current cosmological acceleration suggest that both could be linked. Such a theoretical framework would provide a theory of physics unifying both the infinitely small (the primordial universe) and the infinitely large (the present universe). The ARCCOS project is fully dedicated to these questions through the study of several approaches that could unify inflation and dark energy, and to test them with current and future cosmological data.
Jobs.
