Astroparticle Physics
Astroparticle physics studies the impact of fundamental interactions on cosmological and astrophysical observations, allowing us to test the existence of very massive or very weakly coupled particles. Among these researches, our group is active in the study of particle properties, the origin and detection of dark matter, the identification of new particles from stellar processes, inflation, primordial black holes, and gravitational waves.
Staff
Full Professors:Antonio Masiero, Marco Peloso
Associate Professors: Francesco D’Eramo
Assistant Professors: Edoardo Vitagliano
Post-doc
Jun’ya Kume (JSPS fellow), Ville Vaskonen (MSCA fellow)
PhD students
Federico Greco, Tommaso Sassi
Research activities
Axion Cosmology
The QCD axion is a hypothetical particle strongly motivated by considerations regarding the invariance of the strong interactions under time reversals. This degree of freedom is very light and weakly coupled to visible particles, and consequently may play a prominent role in the early Universe. In recent years I have developed theoretical tools to precisely quantify the abundance of relativistic axions produced after the Big Bang and have predicted observable signals.
Contacts: Francesco D’Eramo
Exotic experimental signals from non-minimal dark sectors.
Given the complexity of visible matter, it is plausible that the sector where dark matter resides is also composed of multiple degrees of freedom. The richness of a non-minimal dark sector leads to experimental signals drastically different from those sought in conventional dark matter searches. In recent years I have proposed several examples along these lines such as unusual events at particle accelerators, detection of X-rays and gamma rays with unique spectral and morphological properties, and modification of the formation of cosmic structures.
Contacts: Francesco D’Eramo
Search for light dark sector particles in ultra-precise low-energy experiments
The presence of new light particles, belonging to hidden sectors of the theory (possibly related to dark matter) with (very) weak couplings to the matter of the visible sector of the Standard Model, can manifest itself, through virtual quantum effects, in an observable way in low-energy experiments with very high-precision measurements. An example of this are the experiments concerning the electric and magnetic dipole moments in both the leptonic and hadronic sectors. The puzzle of the anomalous magnetic moment of the muon still represents a possible clue to a new light and hidden sector of dark matter.
Contacts: Antonio Masiero
Axion-driven inflation.
A field with axion symmetry is an ideal candidate for the inflaton, since this symmetry protects the inflatonic potential from radiative corrections, which would compromise the flatness of the potential needed to drive inflation. The coupling of this field with gauge fields offers a wide range of phenomena, from the generation of primordial density perturbations to gravitational waves observable in the CMB or in ground-based detectors, to the formation of primordial black holes. This coupling can also slow down the motion of the inflaton, allowing inflation even at potentials otherwise too steep to sustain an inflationary expansion. A significant part of my activity is devoted to the study of these effects, using various numerical and analytical techniques.
Contacts: Marco Peloso
Stochastic gravitational wave background.
The measurement of the Cosmological Radiation Background (CMB) has marked a turning point in recent cosmology. Another potential revolution could come from the discovery of the stochastic gravitational wave background. Pulsar timing array experiments have recently highlighted this phenomenon, while other frequency bands are being studied for ground-based detectors such as LIGO-Virgo-KAGRA and, in the future, for the LISA satellite. This opens new perspectives in the study of cosmology, allowing the possible observation of gravitational waves generated by inflation or phase transitions in the early Universe. In my research, I am dedicated to the characterization of this signal, analyzing its spectral dependence, statistics, polarization and spatial distribution.
Contacts: Marco Peloso
Primordial Perturbations Background.
During inflation, particle interactions can generate a diverse array of cosmological signatures, including the non-Gaussianity of the CMB, spectral distortions, a stochastic gravitational wave background observable at different frequencies, and the formation of primordial black holes. Although the literature is rich in proposals that attempt to explain these signatures, it is essential to critically examine them, going beyond the single applications for which they have been put forward. In the course of my research, I have conducted a systematic study of many of these proposals, showing that some of the suggested signatures may not be observable once all the constraints imposed by full model consistency or by signatures different from those initially assumed are taken into account. In the best cases, this extended approach allows to identify a multiplicity of signatures that can strengthen the experimental evidence in favor of the proposed models.
Contacts: Marco Peloso
New table-top experiments to detect dark matter.
One of the most intriguing possibilities in astroparticle physics is to reveal the nature of dark matter in the form of feebly interacting particles (FIPs), such as sterile neutrinos, axions, and other particles beyond the standard model. Since FIPs have small masses, new ideas for detecting them are needed. In my work, I take advantage of the latest results in condensed matter physics to suggest new schemes, for example with metamaterials.
Contacts: Edoardo Vitagliano
Stars and transients as laboratories of fundamental physics.
FIPs are light enough to be produced in abundance in stars during their evolution. By combining astrophysics, finite temperature field theory, and particle physics with the latest observational results, a variety of observables can be used to probe the existence of new particles. I am continually looking for new methods to discover FIPs, using multimessenger observations of supernovae, neutron star mergers, white dwarfs, the Sun, and other celestial bodies
Contacts: Edoardo Vitagliano
Topological defects and primordial black holes.
While ordinary black holes produced by the collapse of stars cannot constitute a large fraction of dark matter, black holes produced in the early universe can have masses comparable to those of asteroids and be the dominant component. In recent years I have been working on one of the most fascinating production mechanisms: the result of the existence, during a period of the universe, of topological defects (cosmic strings, domains) due to high-energy physics, which can collapse and at the same time produce gravitational wave signals
Contacts: Edoardo Vitagliano
