Cosmic strings are predicted by various well-motivated models in high-energy particle physics and are potential sources of a gravitational wave background (GWB) detectable by LISA. Predicting their GWB relies on three key ingredients: the dynamics of the string network, the GW emission from loops, and the cosmic history of the Universe. Each of these components carries theoretical...
We briefly describe an exact formalism, based on the threshold statistics on the compaction function, for the computation of the abundance of primordial black holes in the presence of local non-Gaussianity (NGs) in the curvature perturbation field with a completely generic functional form. As NGs modify the amplitude of perturbations necessary to produce a given PBH abundance, modeling these...
The gravitational wave (GW) interferometers LISA and ET are expected to be functional in the next decade(s), possibly around the same time. They will operate over different frequency ranges, with similar integrated sensitivities to the amplitude of a stochastic GW background (SGWB). We investigate the synergies between these two detectors, in terms of a multi-band detection of a cosmological...
In the quest to explore the distant Universe, gravity’s universal nature provides crucial aid, as any clump of matter may act as a giant lens to magnify the radiation emitted by otherwise too-faint objects. Thanks to the gravitational lensing of electromagnetic waves, we have mapped the elusive dark matter, found the furthest galaxies, and even discovered exoplanets.
Gravitational waves...
Gravitational waves emitted from binary black hole mergers exhibit highly distinctive characteristics. When these waves undergo gravitational lensing, the resulting distortions in amplitude and phase can be identified. This phenomenon can thus be leveraged to probe small-scale dark matter structures that are still largely unexplored. In this talk, I will discuss recent advances in this field,...
In this talk, I will review recent developments in the topic of cosmological phase transitions. I will focus on the description of the thermodynamics of the phase transition and the dynamics of bubbles, but I will also explain the implications for the produced gravitational-wave signals and their observability prospects.
I will present numerical results of strong phase transitions using the so-called Higgsless approach and recent theoretical developments to describe the GW production extending the stationary UETC assumption for sound waves to a locally stationary UETC that allows us to describe decaying sources of gravitational waves. The source of GWs corresponding to compressional motion (sound waves in...
We calculate the gravitational wave power spectrum from sound waves in a cosmological first order phase transition in the unexplored regime of large bubbles, by which we mean that the mean bubble spacing $R_*$ is a non-negligible fraction of the Hubble length $\mathcal{H}_*^{-1}$, i.e. $R_*\mathcal{H}_* \lesssim \mathcal{O}(1)$. Since the amplitude of the gravitational wave signal increases...
Cosmological first-order phase transitions may have generated a gravitational wave background observable with LISA, offering a unique probe of beyond-Standard-Model physics. A crucial step in predicting this background is the reliable computation of bubble nucleation rates. In this talk, I will give an overview of recent advancements in perturbative high-temperature nucleation rate...
Among all the possible candidates for Dark Matter, one appealing example is a population of Primordial Black Holes, which could have been borne by various processes in the early stages of the Universe. In this talk, I will investigate the formation of such objects as the result of the collapse of energy density fluctuations originating from supercooled first-order phase transitions. I will...
We study the stochastic gravitational wave background sourced by a network of cosmic superstrings and demonstrate that incorporating higher-mass string species, beyond the fundamental string, is crucial for accurately modeling the resulting gravitational wave spectrum across frequencies ranging from nanohertz to kilohertz.
Using the multi-tension velocity-dependent one-scale model to evolve...
Superconducting cosmic strings are intriguing relics of high-energy physics beyond the Standard Model, with the potential to leave observable imprints in the form of gravitational waves. In this talk, I will present recent progress on the stochastic gravitational wave background generated by chiral superconducting cosmic string networks. For the first time, we incorporate the effects of vector...
A gravitational wave background from a first order phase transition at the electroweak scale may be observable with future detectors such as LISA. While the Standard Model does not predict a first order phase transition, these occur in many extended scenarios. Therefore, detecting a stochastic gravitational wave background could point to new physics, while a null detection could constrain or...
I will discuss three topics related to the characterization of the stochastic gravitational-wave background using pulsar timing arrays and astrometry: the potential detection of its kinematic dipole, the prospects for measuring its circular polarization, and a novel method for identifying the presence of scalar polarization.
