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Mauro Pieroni (CERN)02/06/2025, 17:30
Simulation-Based-Inference (SBI), also known as likelihood-free inference, is an alternative approach to Montecarlo techniques to perform Bayesian inference. SBI typically relies on Machine Learning (ML) methods to approximate the posterior distribution for some model parameters given the observed data. In the past years, SBI has been applied to a range of physics problems, including...
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Michele Mancarella02/06/2025, 18:00
Gravitational-wave standard sirens provide an independent means of measuring the expansion history of the universe. With growing datasets from currently operational detectors and new experiments under construction (such as LISA) or in development (Einstein Telescope, Cosmic Explorer), standard sirens are gaining significant attention as a powerful cosmological probe. In this talk, I will...
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Alba Romero03/06/2025, 14:00
The gravitational wave background (GWB) is a superposition of weak, independent and unresolved gravitational wave (GW) sources. It can be sourced by both astrophysical and cosmological sources, among which we find unresolved compact binary coalescences, supernovae, first order cosmological phase transitions and cosmic strings. Since the beginning of its observational runs, the LIGO-Virgo-KAGRA...
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Antonio Junior Iovino (Università di Roma "La Sapienza")03/06/2025, 14:30
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...
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Ameek Malhotra03/06/2025, 14:50
The formation of primordial black holes (PBHs) from amplified density fluctuations in the early universe may also generate scalar-induced gravitational waves (GW), carrying vital information about the primordial power spectrum and the universe's expansion history. We present a Bayesian approach to reconstruct both the scalar power spectrum and the equation of state from GW observations, using...
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Anish Ghoshal (University of Warsaw, Poland)03/06/2025, 15:10
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...
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Bogumila Swiezewska04/06/2025, 14:00
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.
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Alberto Roper Pol (Universite de Geneve (CH))04/06/2025, 14:30
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...
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Lorenzo Giombi (University of Helsinki)04/06/2025, 14:50
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...
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Joonas Hirvonen (University of Nottingham)04/06/2025, 15:10
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...
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Piotr Toczek (University of Warsaw)04/06/2025, 15:30
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...
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Giorgio Mentasti05/06/2025, 14:00
We explore the detectability of an anisotropic Stochastic Gravitational Wave Background (SGWB) using LISA
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alone and jointly with the proposed Taiji interferometer. Going beyond traditional frequency-domain approaches, we incorporate the satellites' orbital motion via time-dependent response functions. First, we attempt model-independent reconstruction of the galactic SGWB, finding that both... -
Robert Rosati05/06/2025, 14:30
In this talk I'll describe a stochastic sampler integrated into the GLASS global fit, as well as the challenges of recovering SGWBs as well as the confusion noise. Depending on the galactic population and the galactic binaries' sampler convergence, some regions of the residual can form a non-gaussian noise background. These non-gaussianities can lead to biases in discrete sources and false...
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Henri Inchauspé05/06/2025, 14:50
The LISA Distributed Data Processing Center (DDPC) has kicked off in June 2024, aiming at designing and implementing the data processing and data analysis software and infrastructure to interpret LISA measurement data-streams. An important component of DDPC is the simulation of a representative, synthetics dataset feeding all the building blocks of data processing and analysis to design,...
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Deanna Hooper, Tiina Minkkinen (University of Helsinki)05/06/2025, 15:10
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...
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Ryusuke Jinno (Kobe University)05/06/2025, 15:30
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